CONTRIBUTIONS TO THE EPIDEMIOLOGY OF HEROIN USE By Samantha Jo Bauer A DISSERTATION Michigan State University in partial fulfillment of the requirements Submitted to for the degree of Epidemiology—Doctor of Philosophy 2019 ABSTRACT CONTRIBUTIONS TO THE EPIDEMIOLOGY OF HEROIN USE By Samantha Jo Bauer Background & Aims: Despite the marketing of heroin in 1898 and its history as a public health concern, heroin use has not been a major topic of epidemiologic research (1). Little is known about the problems and experiences (PEs) during the earliest months following newly incident heroin use. These PEs after heroin use onset might arise and co-occur in pairwise or other multivariate association patterns that are consistent with the idea that there is a dimension of heroin use disorder (HUD). It might be assumed that this HUD dimension is comparable across subgroups, such as sex and history of other opioid use, but there is little evidence of this. Lastly, consequences of heroin use have not been fully explored in relation to an emerging public health concern about increased rates of stimulant related overdose concurrent with heroin related overdose. Thus, this dissertation aims: 1) To estimate the pairwise association between PEs of HUD. 2) To assess measurement equivalence of HUD, adopting a single dimension idea, across subgroups defined by sex and extra-medical prescription opioid use (EMPOU) history. 3) To investigate the degree to which onset of heroin use may precipitate excess risk of onset of stimulant use. Methods: The National Surveys on Drug Use and Health (NSDUH), 2002-2016, target population includes non-institutionalized United States (US) civilians age 12 years and older, including inhabitants of households, group quarters, and homeless shelters. Multi-stage area probability sampling identified 837,326 participants, 896 of whom were newly incident heroin users (NIHUs). Time intervals stratified NIHUs by elapsed time between first heroin use (i.e., within 12 months of assessment) and survey assessment. Pairwise combinations of PEs of HUD have been studied; odds ratios (ORs) have been estimated. The PEs were also combined into 10 diagnostic criteria indicators for an evaluation of measurement equivalence. Lastly, a case crossover design and analysis estimated the degree to which NIHU may lead to months of increased risk for starting extra-medical use of prescription stimulants or cocaine. Two-month hazard and control intervals were specified a priori. Results: The majority of PE to PE ORs suggested robust and statistically significant associations throughout time intervals from first use to up to 12 months after first use. Measurement equivalence evaluation indicated no difference between males and females, but suggested lack of measurement equivalence across EMPOU subgroups. Case crossover discordant pair odds ratios show no statistically significant increased risk of newly incident stimulant use within two months of NIHU. A post-estimation exploration of alternatives suggests use of one-month intervals. Discussion: The current study is novel as a US nation-scale community epidemiology study of the natural history of HUD. Other facets of novelty involve its fine-grain stratification of elapsed time since first heroin use, and its focus on individuals and aired PEs that develop over time. This dissertation also draws attention to the need for more precise HUD assessment considering EMPOU. There may be a linkage between NIHU and extra-medical stimulant use, but this topic deserves more attention in future research. Conclusions: First, heroin PEs now begin to coalesce into a HUD syndrome within 90-120 days after first heroin use. Second, female-male contrasts in level of HUD can now be made, but this is not the case for prescription opioid subgroups. Third, this study’s evidence does not confirm a suspected triggering of stimulant use by heroin use. ACKNOWLEDGMENTS I would like to acknowledge Dr. James C. Anthony for his devoted mentorship throughout my PhD education and for him graciously accepting me into his T32 training program. He has been invaluable in my growth as a scientist and his National Institute on Drug Abuse award has made my research and pre-doctoral education possible (T32DA021129). His investment in my education has been an incredible gift. In addition, I would like to acknowledge my guidance committee Dr. Brian Ahmedani, Dr. Ahnalee Brincks, and Dr. Ruben Parra-Cardona. Their valuable help and encouragement throughout the dissertation process gave me the confidence and the subject matter insight to accomplish my goal. I would like to acknowledge Dr. David Barondess for his dedicated guidance throughout my graduate career. His ability to see the forest for the trees, in both education and in matters of the heart, has made him a remarkable mentor and friend. I would also like to thank the entire Department of Epidemiology and Biostatistics for being my academic home over the past years. Together the faculty, staff, and students have irreplaceably balanced education, camaraderie, and care. Lastly, I must acknowledge my mom, dad, and brothers – Brennan, Baron, Bradly, and Bronson. The journey up to the completion of this doctoral degree started long before my formal education. I could not have set out on this venture if it were not for your love and unwavering support. The most important knowledge I have carried with me has always been that I have a home with all of you to come back to. iv TABLE OF CONTENTS LIST OF TABLES ...................................................................................................................... vii LIST OF FIGURES ................................................................................................................... xiii KEY TO ABBREVIATIONS .................................................................................................... xiv CHAPTER 1 INTRODUCTION ................................................................................................. 1 1.0 Introduction ........................................................................................................................... 1 1.1 Specific Aims ........................................................................................................................ 2 CHAPTER 2 BACKGROUND AND SIGNIFICANCE ........................................................... 4 2.0 Heroin .................................................................................................................................... 4 2.0.1 General Introduction ...................................................................................................... 4 2.0.2 Heroin Pharmacology & Physiology ............................................................................. 4 2.1 Opioids Overview ................................................................................................................. 6 2.2 History ................................................................................................................................... 7 2.1.1 From Opium Cultivation to Heroin Synthesis ............................................................... 7 2.2.2 The History of Heroin in the United States ................................................................... 8 2.2.3 America’s Opioids Crisis ............................................................................................. 12 2.3 Heroin Use Disorder ........................................................................................................... 14 2.4 The Main Rubrics of Epidemiology Applied to Heroin Use .............................................. 16 2.5 Significance and Purpose .................................................................................................... 22 CHAPTER 3 MATERIALS – NATIONAL SURVEYS ON DRUG USE AND HEALTH . 24 3.0 Chapter Overview ............................................................................................................... 24 3.1 The Population Under Study ............................................................................................... 24 3.2 Cross-Sectional Survey Design and Probability Sampling Approach ................................ 26 3.3 Human Subjects Protection ................................................................................................. 26 3.4 Participation Rates and Assessment Protocol ..................................................................... 27 3.5 Statistical Analysis .............................................................................................................. 30 CHAPTER 4 MANUSCRIPT 1 – THE NATURAL HISTORY OF HEROIN USE DISORDER EXPLAINED BY PROBLEMS AND EXPERIENCES FROM FIRST MONTHS OF USE TO UP TO A YEAR AFTER ONSET .................................................... 32 4.0 Abstract ............................................................................................................................... 32 4.1 Introduction ......................................................................................................................... 33 4.2 Methods ............................................................................................................................... 38 4.3 Results ................................................................................................................................. 46 4.4 Discussion ........................................................................................................................... 86 4.5 Conclusions ......................................................................................................................... 91 CHAPTER 5 MANUSCRIPT 2 – EVALUATING MEASUREMENT EQUIVALENCE OF HEROIN USE DISORDER ACROSS HISTORY OF EXTRA-MEDICAL PRESCRIPTION OPIOID USE AND SEX ............................................................................. 93 5.0 Abstract ............................................................................................................................... 93 v 5.1 Introduction ......................................................................................................................... 95 5.2 Methods ....................................................................................................................... 101 Results ......................................................................................................................... 113 5.3 Discussion ................................................................................................................... 114 5.4 5.5 Conclusions ................................................................................................................. 116 CHAPTER 6 MANUSCRIPT 3 – WILL THE OPIOIDS CRISIS PRECIPITATE EXCESS RISK OF A STIMULANT CRISIS? ....................................................................................... 119 6.0 Abstract ............................................................................................................................. 119 6.1 Introduction ....................................................................................................................... 121 6.2 Methods ............................................................................................................................. 124 6.3 Results ............................................................................................................................... 130 6.4 Discussion ......................................................................................................................... 131 6.5 Conclusions ....................................................................................................................... 135 CHAPTER 7 DISCUSSION AND CONCLUSIONS ............................................................. 138 7.0 Summary of Findings ........................................................................................................ 138 7.1 Strengths and Limitations ................................................................................................. 140 7.2 Public Health Implications and Next Steps ...................................................................... 141 7.3 Conclusions ....................................................................................................................... 145 APPENDICES ........................................................................................................................... 147 APPENDIX A – IRB DETERMINATION ......................................................................... 148 APPENDIX B – MANUSCRIPT 1 ...................................................................................... 150 APPENDIX C – MANUSCRIPT 2 ...................................................................................... 185 APPENDIX D – MANUSCRIPT 3 ...................................................................................... 188 BIBLIOGRAPHY ..................................................................................................................... 190 vi LIST OF TABLES Table 1. Diagnostic Criteria for Substance Use Disorders Defined by the Diagnostic and Statistical Manual. ......................................................................................................................... 15 Table 2. Population Projections of Newly Incident Heroin Users and Dependence .................... 17 Table 3. United States Overdose Deaths by Drug. ....................................................................... 18 Table 4. Contrast of Heroin Knowledge Based on Lee Robins’ Study of Vietnam Veterans Return to the United States. .......................................................................................................... 36 Table 5. Description of Problems and Experiences of Heroin Use Disorder Included in the Diagnostic and Statistical Manual. ............................................................................................... 37 Table 6. Description of Lag-Time Intervals Indicating Elapsed Time Between Newly Incident Heroin Use and Survey Assessment. ............................................................................................ 44 Table 7. Characteristics of Overall Sample and Newly Incident Heroin Use Analytic Sample. .. 45 Table 8. Description of Problems and Experiences of Heroin Use Disorder. ............................. 52 Table 9. Weighted Odds Ratios of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. ................................................................................................................................ 53 Table 10 Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 0- 90 Days of First Using Heroin. ..................................................................................................... 54 Table 11. Weighted Odds Ratios of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. ................................................................................................................................ 55 Table 12. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 1- 120 Days of First Using Heroin. ................................................................................................... 56 Table 13. Weighted Odds Ratios of Problem and Experience Pairs Within 30-150 Days of First Using Heroin. ................................................................................................................................ 57 Table 14. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 90 Days of First Using Heroin. .......................................................................................................... 58 Table 15. Weighted Odds Ratios of Problem and Experience Pairs Within 60-180 Days of First Using Heroin. ................................................................................................................................ 59 Table 16. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 60-180 Days of First Using Heroin. .............................................................................................. 60 vii Table 17. Weighted Odds Ratios of Problem and Experience Pairs Within 150 Days of First Using Heroin. ................................................................................................................................ 61 Table 18. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150 Days of First Using Heroin. ................................................................................................... 62 Table 19. Weighted Odds Ratios of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. ................................................................................................................................ 63 Table 20. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. ............................................................................................ 64 Table 21. Weighted Odds Ratios of Problem and Experience Pairs Within 150-270 Days of First Using Heroin. ................................................................................................................................ 65 Table 22. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150-270 Days of First Using Heroin. ............................................................................................ 66 Table 23. Weighted Odds Ratios of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. ................................................................................................................................ 67 Table 24. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. ............................................................................................ 68 Table 25. Weighted Odds Ratios of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. ................................................................................................................................ 69 Table 26. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. ............................................................................................ 70 Table 27. Weighted Odds Ratios of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. ................................................................................................................................ 71 Table 28. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. ............................................................................................ 72 Table 29. Weighted Odds Ratios of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. ................................................................................................................................ 73 Table 30. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. ............................................................................................ 74 Table 31. Weighted Odds Ratios of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. ................................................................................................................................ 75 Table 32. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. ............................................................................................ 76 viii Table 33. Weighted Odds Ratios of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. ................................................................................................................................ 77 Table 34. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. ............................................................................................ 78 Table 35. Sensitivity Analysis: Weighted Odds Ratios of Problem and Experience Pairs Within 0-150 Days of First Using Heroin. ................................................................................................ 80 Table 36. Sensitivity Analysis: Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 0-150 Days of First Using Heroin. ........................................................ 81 Table 37. Sensitivity Analysis: Weighted Odds Ratios of Problem and Experience Pairs Within 150-300 Days of First Using Heroin. ............................................................................................ 82 Table 38. Sensitivity Analysis: Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150-300 Days of First Using Heroin. .................................................... 83 Table 39. Sensitivity Analysis: Weighted Odds Ratios of Problem and Experience Pairs Within 300-390 Days of First Using Heroin. ............................................................................................ 84 Table 40. Sensitivity Analysis: Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 300-390 Days of First Using Heroin. .................................................... 85 Table 41. Problems and Experiences of Heroin Use Based on Diagnostic Criteria. .................... 99 Table 42. DSM-5 Use Disorder Criteria and Corresponding Heroin Use Disorder Problems and Experiences. ................................................................................................................................ 100 Table 43. Description of Confirmatory Factor Analysis Measurement Equivalence ................. 100 Table 44. Characteristics of Newly Incident Heroin Use Sample. ............................................. 106 Table 45. Description of Problems and Experiences involving Heroin Use Disorder. .............. 107 Table 46. Description of DSM-5 Criteria for Heroin Use Disorder. .......................................... 108 Table 47. Goodness of Fit Indices Evaluating Measurement Equivalence of Heroin Use Disorder Level Across Sex Among Newly Incident Heroin Users (Without Analysis Weights). ............ 109 Table 48. Goodness of Fit Indices Evaluating Measurement Equivalence of Heroin Use Disorder Level Across Sex Among Newly Incident Heroin Users with Analysis Weights. ..................... 110 Table 49. Goodness of Fit Indices Evaluating Measurement Equivalence of DSM-5 Criteria for Heroin Use Disorder Level Across History of Extra-Medical Prescription Opioid Use Among Newly Incident Heroin Users (Without Analysis Weights). ...................................................... 111 ix Table 50. Goodness of Fit Indices Evaluating Measurement Equivalence of DSM-5 Criteria for Heroin Use Disorder Level Across History of Extra-Medical Prescription Opioid Use Among Newly Incident Heroin Users with Analysis Weights. ............................................................... 112 Table 51. Characteristics of Newly Incident Stimulant Use Sample. ......................................... 126 Table 52. Counts and Discordant Pair Odds Ratios of Newly Incident Heroin Use Preceding Newly Incident Stimulant Use. ................................................................................................... 127 Table 53. Post Hoc Interval Width Exploration: Unweighted Discordant Pair Odds Ratios of Newly Incident Heroin Use Preceding Newly Incident Stimulant Use. ..................................... 128 Table 54. Year-Specific Numbers of NISUs Stratified by Analysis Weight Quartiles and Interval-Specific Exposure Status. .............................................................................................. 129 Table 55. Year-Specific Odds Ratios of NISUs Stratified by Analysis Weight Quartiles and Interval-Specific Exposure Status ............................................................................................... 130 Table 56. Manuscript 1 - Stata Code .......................................................................................... 151 Table 57. Meta-Analysis of Newly Incident Heroin Use to Dependence Probabilities. ............ 158 Table 58. Unweighted Odds Ratios of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. .............................................................................................................................. 159 Table 59. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. ................................................................................................ 160 Table 60. Unweighted Odds Ratios of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. .............................................................................................................................. 161 Table 61. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. .............................................................................................. 162 Table 62. Unweighted Odds Ratios of Problem and Experience Pairs Within 30-150 Days of First Using Heroin. ...................................................................................................................... 163 Table 63. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 30-150 Days of First Using Heroin. ............................................................................................ 164 Table 64. Unweighted Odds Ratios of Problem and Experience Pairs Within 60-180 Days of First Using Heroin. ...................................................................................................................... 165 Table 65. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 60-120 Days of First Using Heroin. ............................................................................................ 166 Table 66. Unweighted Odds Ratios of Problem and Experience Pairs Within 90-210 Days of First Using Heroin. ...................................................................................................................... 167 x Table 67. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 90-210 Days of First Using Heroin. ............................................................................................ 168 Table 68. Unweighted Odds Ratios of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. ...................................................................................................................... 169 Table 69. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. .......................................................................................... 170 Table 70. Unweighted Odds Ratios of Problem and Experience Pairs Within 150-210 Days of First Using Heroin. ...................................................................................................................... 171 Table 71. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150-270 Days of First Using Heroin. .......................................................................................... 172 Table 72. Unweighted Odds Ratios of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. ...................................................................................................................... 173 Table 73. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. .......................................................................................... 174 Table 74. Unweighted Odds Ratios of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. ...................................................................................................................... 175 Table 75. Unweighted Odds Ratios of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. ...................................................................................................................... 176 Table 76. Unweighted Odds Ratios of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. ...................................................................................................................... 177 Table 77. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. .......................................................................................... 178 Table 78. Unweighted Odds Ratios of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. ...................................................................................................................... 179 Table 79. Unweighted Odds Ratios of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. ...................................................................................................................... 180 Table 80. Unweighted Odds Ratios of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. ...................................................................................................................... 181 Table 81. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. .......................................................................................... 182 Table 82. Unweighted Odds Ratios of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. ...................................................................................................................... 183 xi Table 83. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. .......................................................................................... 184 Table 84. MPlus Code to Evaluate Measurement Equivalence for Heroin Use Disorder Among Newly Incident Heroin Users. ..................................................................................................... 186 Table 85. Stata Code Used to Yield Case Crossover Discordant Pair Odds Ratios Displayed within Manuscript 3. ................................................................................................................... 189 xii LIST OF FIGURES Figure 1. Chemical Structure of Heroin .......................................................................................... 5 Figure 2. Centers for Disease Control and Prevention: 3 Waves of the Rise in Opioid Overdose Deaths ........................................................................................................................................... 14 Figure 3. Five Main Rubrics of Epidemiology as Applied to Drug Dependence ......................... 16 Figure 4. Description of Heroin Use Disorder in the Past Year among Individuals Aged 12 or Older, by Age Group: Percentages. .............................................................................................. 19 Figure 5. Probability of Transition from Heroin First Use to Dependence within One Year. ...... 21 Figure 6. Declining Response Rates of Federally-Funded National Surveys ............................... 29 Figure 7. Declining Response Rates - National Surveys on Drug Use and Health ...................... 30 Figure 8. Flow of Participants in Newly Incident Heroin Use Case Ascertainment. ................... 43 Figure 9. Odds Ratios with 95% Confidence Intervals of Problem and Experience Pairs Stratified by Analysis Weight Quartiles. ...................................................................................................... 79 Figure 10. Diagram of Confirmatory Factor Analysis Model Testing Measurement Equivalence of Problems and Experiences of Heroin Use Disorder Among Newly Incident Heroin Users. . 101 Figure 11. Flow of Participants in Newly Incident Heroin Use Case Ascertainment. ............... 105 Figure 12. Diagram of Case Crossover Design Studying Newly Incident Heroin Use and Excess Risk of Newly Incident Stimulant Use. ...................................................................................... 123 Figure 13. An epidemic curve for acute-onset disease following a point exposure. .................. 135 Figure 15. Infographic Exerts for Citizen Science-Based Initiative ........................................... 143 Figure 16. Flow of Heroin Use Disorder Questionnaire Based on DSM-IV Criteria ................. 156 xiii KEY TO ABBREVIATIONS CFA – Confirmatory Factor Analysis CI – Confidence Intervals DC – District of Columbia DSM – Diagnostic and Statistical Manual EMPOU – Extra-Medical Prescription Opioid Use FI – Field Interviewer HUD – Heroin Use Disorder NIHU – Newly Incident Heroin Use NISU – Newly Incident Stimulant Use NSDUH – National Surveys on Drug Use and Health OR – Odds Ratio PE – Problems and Experiences PPR – Prescription Pain Relievers SC – Psychostimulants including Cocaine US – United States xiv CHAPTER 1 INTRODUCTION 1.0 Introduction The use of heroin and other opioids has become a major public health concern, in the US and in countries around the world. In many countries, individuals who use opioids experience higher crude mortality rates and a higher risk of death than the general population (2)(3)(4). Epidemiologic research from an international systematic review suggests all cause crude mortality among regular or dependent users of heroin to be 2.09 per 100 person-years (95% CI=1.93, 2.26), with a standardized mortality rate at 14.66 (95% CI=12.82, 16.50) (2). The position of heroin use as an important health concern is further highlighted by research on the disability-adjusted life years (DALYs) for opioid use disorders, recently estimated 9,152,000 (95% CI=7,066,000, 11,443,000)(5). Motivated by the morbidity and mortality among heroin users, this dissertation will delineate implications of heroin use and use disorder. Over the past two decades the United States (US) has and continues to experience opioids crises in that the use of prescription opioids, heroin, and synthetic opioids have sequentially increased in nearly all demographic sub-groups. Evidence of these opioid crises is seen by the nearly five-fold increase in opioid overdose deaths from 1999 to 2016 (3). Heroin is a prominent driver of the mortality increase, as heroin-related overdose deaths alone have increased five-fold from 2010 to 2016 (6). In response to the opioids crises, public health has targeted the healthcare sector to promote responsible prescribing practices of opioids and has increased awareness among communities and the public safety sector. Even so, public health has yet to alleviate the heroin use crisis. A strategic effort to understand and intervene on heroin use is imperative for several reasons: 1) alone heroin was responsible for roughly 15,500 deaths in 2016 (6), 2) heroin use disorder, infection, psychiatric comorbidities, and poor quality of life are just some of the 1 outcomes associated with heroin use, and 3) heroin is increasingly being laced with synthetic opioids (i.e., fentanyl and its derivatives), which increases risk of overdose. At present, the presence of adulterants such as fentanyl is may or may not be known to users. Through this dissertation, natural history of heroin use disorder (HUD) is investigated from the first months of use to the development of use disorder with consideration of heroin use disorder dimensionalities and drug use trajectories. The overarching goal is to understand the HUD natural history from the most granular perspective possible to provide targeted public health primary prevention efforts. Additional implications may also lend themselves to clinicians, health professionals, and communities by providing early tell-tale signs of HUD forming in individuals. Rationale for HUD investigation is evident from the sparse epidemiologic literature on its natural history, measurement equivalence, and trajectories. Past studies have often been limited by the reliance on treatment-seeking samples, often with left-censoring problems and selection bias, or by HUD case definitions or lifetime history recall bias (2)(7)(5). Given these study design limitations and the dynamic and unprecedented landscape of the nation’s current heroin and other opioid crises, new HUD research is needed. 1.1 Specific Aims Specific Aim 1. To estimate the pairwise association between problems and experiences of heroin use disorder, interval by interval, forward across the first months of use. Specific Aim 2. To assess measurement equivalence of heroin use disorder, assuming a single dimension, with evaluation of non-equivalence for sex and extra-medical prescription opioid use subgroups. Specific Aim 3. To investigate the degree to which onset of heroin use might precipitate onset of extra-medical stimulant use. 2 At this stage, four abbreviations can be introduced. HUD is heroin use disorder. NIHU is newly incident heroin user. EMPPR and EMSC refer to extra-medical use of prescription pain relievers (PPR) or psychostimulants including cocaine (SC). 3 CHAPTER 2 BACKGROUND AND SIGNIFICANCE 2.0 Heroin 2.0.1 General Introduction Heroin is a semi-synthetic opioid derived from the opium poppy, Papaver somniferum, which is typically grown in warm, dry climates such as southern Asia and Latin America (8). From the poppy’s seed pod, morphine is extracted and then converted to diacetylmorphine (i.e., heroin), which may be sold as a white or brown powder or a sticky black tar (8)(9). Individuals can then smoke, snort, inject, or orally administer the product (9). Notably, “on the streets” heroin is frequently “cut” with products ranging from sugar or powdered milk to synthetic opioids such as fentanyl (9). “Street” names include but are not limited to black tar, horse, smack, thunder, big H, and hell dust (10). In addition, the term “narcotic” from the Greek word for “stupor”, also refers to opioids. The US Drug Enforcement Administration’s (DEA) Controlled Substances Act (CSA) categorizes drugs into five schedules based on the drug’s accepted medical use and potential for abuse or dependence. Schedule I drugs have the highest potential for dependence and no accepted medical use in the US, whereas Schedule V drugs have the relatively lowest potential for dependence and may be used medically (10). Often Schedule V drugs are sold over the counter without prescription, as is the case of cough syrup containing small doses of opioids. Heroin is classified as Schedule I and is considered illegal in the US (9)(10). 2.0.2 Heroin Pharmacology & Physiology The chemical structure of heroin, also known as diamorphine or diacetylmorphine, is similar to that of morphine, but can be distinguished by the addition of two acetyl groups (Figure 1) (11)(12). The lipid solubility and quick onset of effects distinguish heroin and might promote its having a higher probability for dependence (11). In the body heroin is quickly metabolized to 4 morphine, since heroin’s half-life is roughly two minutes (13). Thus, the physiological effects of heroin and morphine are comparable. The lipid solubility and quick onset of effects distinguish heroin as having a higher probability for dependence (13). Furthermore, the probability of dependence is exacerbated when heroin is administered intravenously when these effects are felt even sooner than other routes of administration (14). Figure 1. Chemical Structure of Heroin Link: https://pubchem.ncbi.nlm.nih.gov/image/imagefly.cgi?cid=5462328&width=300&height=300 Heroin: C21H23NO5, also known as diamorphine or diacetylmorphine. Source: Pub Chem: Open Chemistry Database, 2018 (12). Opioid receptors are found throughout the central and peripheral nervous systems and are intended to be stimulated by endogenous opioids (15). That is, the identification of opioid receptors in the brain led scientists to research what in the brain could be a natural activator of the receptors. In the process, enkephalins and endorphins were identified as neurotransmitters with actions similar to morphine (11). These endogenous (e.g., endorphins) and exogenous (e.g., heroin) opioids may act on four different classes of opioid receptors, mu, kappa, delta, sigma, categorized by their prototype agonist (15). All classes are G-coupled protein receptors and can bind agonists, partial agonists, and antagonists (14). More specifically, the mu-opioid receptor agonists include morphine and heroin, which primarily produce rewarding analgesic effects and with locations that include brainstem and 5 medial thalamus (16). Other functions of mu-opioid receptors include respiratory depression, sedation, decreased gastrointestinal motility, physical dependence, and rewarding effects (e.g., subjective high, euphoria) (15). Furthermore, the binding of heroin to mu-opioid receptors in the central nervous system activates the release of dopamine (i.e., neurotransmitter related to desire) in the nucleus accumbens, a region that is important in the brain’s reward circuit (17)(18). Additional brain regions important in the physiological effects of heroin include the locus coeruleus, amygdala, dorsal raphe nucleus, and ventral tegmental area (16). Altogether, these areas are involved in the body’s stress response, reward circuit, emotions and motivation, serotonin activation (i.e., neurotransmitter related to satiety and inhibition), and cognition (16)(17)(18). Chronic use of exogenous opioids (e.g., heroin) affects the brain differently in that the pulsatile and phasic activation of mu-opioid receptors can be disrupted and may lead to the dysregulation of receptor recycling and abnormal cell desensitization (16). These neuronal adaptations, among others, may result in HUD, tolerance, and a withdrawal syndrome, although a single definitive mechanism has not been confirmed (16). Common functional consequences of heroin use include: liver disease, gastrointestinal disruption (e.g., constipation), impaired visual acuity, sclerosed veins (i.e., commonly referred to as “tracks”) peripheral edema, infections from unsafe injection practices (e.g., HIV, hepatitis, bacterial endocarditis). Disrupted sexual function and reproduction (e.g., irregular menses) also have been observed (19). 2.1 Opioids Overview Opioids include natural, semi-synthetic, and synthetic compounds that bind to opioid receptors in the brain, with effects such as pain relief, as well as anti-diarrheal and anti-tussive effects (11). Natural opioids include codeine and morphine, which are naturally occurring 6 compounds from the opium poppy. Semi-synthetic opioids, such as heroin, are those derived from opium poppy compounds. Both natural and semi-synthetic opioids are often referred to as opiates. More specifically, opiates are the naturally occurring alkaloids found in the opioid poppy (15). Synthetic opioids are not derived from the opium poppy but bind to opioid receptors and produce similar physiological effects (11). Common synonym terms for opioids include: narcotics, pain relievers, and analgesics, although some drugs in these drug sub-types are not opioids. 2.2 History 2.1.1 From Opium Cultivation to Heroin Synthesis The date of opium poppy cultivation is uncertain, but may be seen as early as the 9th century BC in Homer’s description of Helen, daughter of Zeus, preparing a drug to forget grief in “The Odyssey” (1). While authors have debated over whether ambiguous ancient writings have described opium, there is evidence of opium poppy cultivation by the Sumerians in third century BC in the vicinity of contemporary Iraq (1). Opium and the poppy were referred to as “gil” and “hul gil” meaning “joy” and “plant of joy”, respectively (1). During this time, opium was primarily was used in religious rituals and was considered to be healing (1). Earlier, in 1500 BC, the Ebers Papyrus has been interpreted with a reference to opium for its ability to prevent children from crying and for surgical pain relief, although opium was not widely used. Thereafter, opium was spread to India, China, Asia Minor, and all of Europe throughout the 8th-13th centuries AD. It was not until the 16th century though, that drug abuse and tolerance became mentioned in texts aout modern Turkey, Egypt, Germany, and England. Later, smoking opium was made popular by China’s ban on smoking tobacco during the 17th century (11)(1). Despite efforts to decrease the sale and use of opium, trade became popular with the British and French (1). 7 In 1806, F. Sertürner discovered morphine as an active ingredient in opium, which was then named from the Greek god of dreams, Morpheus (11). Not long after in 1832, codeine was isolated form opium by Pierre Jean Robiquet and named from the Greek word “kodeia” which translated to “poppy head” (11). Use of these compounds increased in prevalence with the invention of the hypodermic syringe and hollow needle in the early 19th century. After the Civil War in 1861-1865, opioid use greatly increased as the hypodermic needle was available wholesale (20). At this time opiates could be used for surgery, postoperative and chronic pain, along with general anesthetics (1). In addition, the various medical preparations of opium, such as cough syrups and pain-killers, further helped to increase opium and morphine’s popularity (20). Via chemical experimentation heroin was synthesized in 1874 by Charles Romley Alder Wright, but initially there was no practical use identified (21). It was not until 1897 that Felix Hoffmann made heroin in effort to develop a safer, non-addictive opiate. Hoffmann, a chemist for the Bayer Company in Germany, made way for Bayer to introduce the compound in 1889 as heroin, named for the German word “heroisch”, meaning “hero” (1)(21). At this time, heroin was believed to be more effective than morphine without the potential to develop dependence (11). In fact, heroin was recommended for the treatment of morphine dependence (also termed ‘morphinomania’) and was generally regarded as an overall safe alternative included in cough suppressants and various medical preparations (20). 2.2.2 The History of Heroin in the United States Despite the initial belief that heroin was a safe alternative to morphine, by the 20th century the development of tolerance, dependence, and intense withdrawal syndrome were eventually realized (11)(21). Heroin’s eventual rise in popularity was set in the context the US’ increasingly opioid dependent population. Nearly one percent of Americans were dependent on 8 opioids given the lack of government regulations, drug availability, inexpensiveness, effectiveness, socially acceptable environment, and the freedom of individuals to self-medicate (20). Notably, at the time it was not heroin that was driving prevalence of opioid dependence, but rather morphine and the oral-intake and smoking of opium (11). Many of the chronic opioid users were women who became dependent via self-medication with over the counter opioids or had received legal physical prescriptions (11). As a result of growing medical concerns and advance legislation at the local and state level, in 1906 the Pure Food and Drugs Act was passed which helped increase consumer protection by banning adulterated and mislabeled products (20). The warnings of the indiscriminate use of opium slowly increased and physicians were largely thought to be responsible for the population’s opioid dependence (11). Physicians’ trust of opioids possibly is understandable, given the pharmaceutical recommendation that morphine was an advantageous treatment option for alcohol dependence. Morphine being inexpensive and available for self- medicating only exacerbated the population’s opium problem (11)(20). In 1914 the Harrison Act was implemented and served to regulate and tax the production, importation, and distribution of opiates and coca products, as well as their derivatives and preparations (11) (20). The act led to a significant shift in the environment from one that allowed opioids to be purchased at local pharmacies or from physicians to one that created black markets with illegal drug dealers (11). Physicians were still able to prescribe opioids to maintain an individual’s dependence, yet apparently few would do so given the drastic change in attitudes (11). Under these circumstances, heroin became the most popular opioid that pleased both dealers and users for its potency and easy concealment. Furthermore, the large price increase from change in markets (i.e., from pharmacies to illegal dealers) led users to inject heroin to experience the drug’s greatest effect (11).The Harrison Act essentially criminalized drug 9 dependence rather than treat it as a health issue and led to the public’s stigmatization of individuals dependent on drugs (11)(20). Soon after, in 1924, the US Congress banned the importation of opium for the purpose of manufacturing heroin in 1924 (21). Between World War I and World War II (WWII), that is around 1918-1939, heroin use in the US declined among women and others in the general public, and became more limited to subgroups considered “outsiders”, such as musicians and ethnic minorities (22)(23). WWII interrupted trade routes from opium-producing countries and caused a five year hiatus of heroin use in the US, but was followed by an increased market around 1947-1951 due to a renaissance of heroin that was of high quality and low cost (23). Moreover, the decades following WWII saw widespread use of various drugs to the point that high school youth became highly affected (22). Consequently, the increased demand for heroin resulted in the price increasing. In response, during this time, the US strengthened its federal controls over drug use, partially in response to the public’s heightened awareness of criminal activity associated with heroin use (24). Social cohesion amongst users and organized crime that sold drugs disintegrated and the market opened up for independent drug dealers. Thereafter, during the late 1960s, the nation faced a decline in heroin supply which drove up the price (23). Looking forward to 1971, the Vietnam War of the 1960s helped fuel US experience with heroin. An estimated 10-15% of American troops deployed in Vietnam became dependent on heroin after consumption of opioids made available at low cost, sometimes in the form of opium to be smoked in a traditional pipe, but also in the form of heroin, also often smoked (11). The purity, availability, and inexpensive-nature of heroin contributed to it being considered the “main drug” of almost 10% of those using (25). Notably, heroin use is usually paired with use of other drugs and alcohol. Nevertheless, in response to the troops’ heroin use the US Department of Defense relied on Dr. Jerome Jaffe’s urine-screening program to test for the presence of heroin in 10 individuals about to return home to the US. Troops that tested positive for heroin were briefly detained for treatment and sent home upon a negative screen. Following the screening effort, Dr. Lee Robins’ follow-up study estimated that only one to two percent of veterans used opioids eight to 12 months after returning home to the US, which was roughly the same percentage of individuals using opioids at the start of military service (11)(25). Contrary to popular belief, follow-up showed that continued and compulsive heroin use and dependence are not inevitable in the natural history of heroin use (25)(26). The 1970s remained an influential time in heroin’s history as criminalization of drug use continued with the implementation of the Drug Enforcement Administration’s Controlled Substances Act in 1970. This classified heroin as a Schedule I drug, among the five drug schedules, making it illegal to produce or consume (10). Also at this time, Turkey became a major source of opium, which was then converted to heroin in the southern part of France (i.e., known as “the French connection”) (11). To taper American’s use of heroin, in 1972 the US paid Turkey $35 million to ban opium cultivation and simultaneously partnered with the French to ultimately reduce the US’ heroin supply. To recap this era, President Nixon took office in 1969 and diverted much attention to the “War on Drugs” which was declared in 1971 (24). In response to the public’s concern for increased drug use and the US military’s heroin use during the Vietnam War, Nixon headed important initiatives to diminish the US heroin epidemic of the 1960s/1970s: 1) The elimination of Turkey as the primary source of US heroin and attacking the “French Connection” where opium was converted to heroin, 2) The creation of federal institutions focused on drug use (i.e., Special Action Office for Drug Abuse Prevention (SAODAP) and National Institute on Drug Abuse), and 3) Overall afforded resources for drug issue by increasing federal spending from 11 $83 million in 1969 to $730 million in 1973 (24). All and all, this time impacted the nation’s relationship with drugs which is still felt today in the 21st century. The reduction in US heroin use was short lived and Mexico became the leading US supplier of heroin in 1975. Mexico’s heroin was commonly referred to as Mexican Brown or Black Tar and was characterized by its high purity and inexpensive nature. Although the US did work with Mexico to eradicate opium production, overall the 1970s heroin use epidemic was slow to decline. Following the 1970s the majority of US heroin came from Southwest Asia, Mexico, and South America. By the end of the 20th century, heroin use was considered rare with only a fraction of the population using (11). 2.2.3 America’s Opioids Crisis Today the US is experiencing an opioids epidemic that has roots starting in the late 1990s when the call for improved pain management strengthened among various organizations and state medical boards (27)(28). For example, organizations such as the Institute of Medicine, the American Pain Society, and the US Veterans Health Administration advocated a message of “Pain: The Fifth Vital Sign”. Likewise, the Joint Commission on the Accreditation of Health Care Organizations supported this movement by compiling examples of standards (e.g., the Institute of Medicine’s “Pain: The Fifth Vital Sign”) and emphasized the need for pain awareness (28)(29). Importantly, the Joint Commission states that they never implemented the standard of pain as a fifth vital sign (28). These pain awareness efforts contributed to a large increase in opioid prescribing for non-cancer pain. Concurrently, the pharmaceutical intensified opioid prescribing by aggressively marketing opioids as highly effective, safe, and without adverse effect when directed by a physician (27). Purdue Pharma has received much of the public blame for its approaches to marketing and increasing market share of prescription opioids, but it was not the only vendor of 12 prescription opioids to take advantage of the opportunities created in the evolving American scene. In addition, there were processes such as prescribers writing prescription orders for 10-14 days of post-surgery pain relief when 1-3 days might have sufficed. The result seems to have included an accumulation of unused prescription opioid dosage units in American homes, and made available for diversion toward extra-medical use (30). Importantly, the rise in opioid prescribing was followed by increases in opioid overdose deaths and dependence. By 2008, the US experienced one opioid-related death every 36 minutes (27). In response to prescription opioid concern, stricter prescribing practices and non- pharmacological strategies for pain management were endorsed by the Joint Commission and various organizations (29). Despite the curtail of opioid prescriptions, an unintended failure of the success (e.g., responsible prescribing practices) was the second wave of the opioids epidemic in 2010 (Figure 2) (31). This wave developed in the context of an already high prevalence opioid dependence so, to maintain opioid dependence and avoid withdrawal many turned to using heroin. The heroin use epidemic between 2010-2016 saw a five-fold increase in heroin overdose deaths (31). In 2013, a third wave of the opioids epidemic emerged with the increased use of synthetic opioids (e.g., fentanyl). By 2016, overdose deaths due to synthetic opioids (e.g., fentanyl) surmounted that of heroin (31). Though given that the presence of synthetic opioids is often hidden within heroin and other drugs to “cut” the supply, heroin use remains a substantial threat today. 13 Figure 2. Centers for Disease Control and Prevention: 3 Waves of the Rise in Opioid Overdose Deaths Link: https://www.cdc.gov/drugoverdose/images/epidemic/3-waves-of-the-rise-in-opioid- overdose-deaths.JPG Source: CDC, National Vital Statistics System Mortality File, 2017 (31). 2.3 Heroin Use Disorder The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM) outlines criteria for drug use disorders with 10 separate drug classes: alcohol, caffeine, cannabis, hallucinogens, inhalants, opioids, sedatives, hypnotics, anxiolytics, stimulants, tobacco, and other known drugs. DSM-IV differentiated ‘drug use’ and ‘drug dependence’ with abuse criteria focused on the negative consequences of drug use (e.g., problems with family), while dependence criteria involved experiences of tolerance, withdrawal, and uncontrolled use (17). The most current version of the DSM, DSM-5, has shifted to diagnosing use disorders as a single disorder rather than differentiated abuse from dependence as separate diagnostic categories. DSM-5 also encouraged a more dimensional approach, with mild, moderate, and severe sub-classifications. However, a majority of DSM-5 criteria overlap with those of DSM-IV (17). 14 The DSM-5 criteria for use disorders are categorized into four groupings: impaired control, social impairment, risky use, and pharmacological, and there are 11 criteria corresponding to use disorder symptoms (Table 1). Diagnoses are determined based on the number of symptoms present, with 0-1 being no disorder, 2-3 being mild, 4-5 being moderate, and 6 or more being severe use disorder (17)(19). Importantly, the change from DSM-IV to DSM-5 diagnoses signifies a departure from a dichotomized framework of dependence (i.e., an individual either has or does not have the use disorder) to a diagnostic gradation that acknowledges a potentially slow development of use disorder in attempt to identify disease early on (17)(19). In addition, tolerance and withdrawal are no longer deciding factors of dependence which allows for even earlier diagnosis and allows use disorder diagnoses for drugs that may not produce a withdrawal syndrome (17). In addition, while the presence of biomarkers is not necessary to diagnosis HUD, urine toxicology screening for heroin will remain positive for 12-36 hours after administration (17). Table 1. Diagnostic Criteria for Substance Use Disorders Defined by the Diagnostic and Statistical Manual. Grouping Impaired control Criterion Social impairment # 1 2 3 4 5 6 7 8 9 10 11 Number of symptoms present: 0-1 = no disorder, 2-3 = mild, 4-5 = moderate, and 6 or more = severe Source: American Psychiatric Association, 2013 (19). Using in larger amounts or for longer than intended Wanting to cut down or stop using, but not managing to Spending a lot of time to get, use, or recover from use Craving Inability to manage commitments due to use Continuing to use, even when it causes problems in relationships Giving up important activities because of use Continuing to use, even when it puts you in danger Continuing to use, even when physical or psychological problems may be made worse by use Increasing tolerance Withdrawal symptoms Risky use Pharmacological 15 2.4 The Main Rubrics of Epidemiology Applied to Heroin Use Adapted from Morris’ 1957 “seven uses of epidemiology”, Anthony’s 2002 “five main rubrics of epidemiology” detail the general research questions that must be answered to progress epidemiology and specifically that of drug dependence (Figure 3) (32)(33). The following section uses the five rubrics of epidemiology to organize the current state of heroin use in the United States. Figure 3. Five Main Rubrics of Epidemiology as Applied to Drug Dependence Link: https://acnp.org/wp-content/uploads/2017/11/C109_1557-1574.pdf Source: Anthony, 2002 (32). Quantity: The prevalence of heroin has increased worldwide over recent years. The crudest evidence of the increased quantity of heroin is the increased cultivation of the opium poppy and opium production (i.e., respectively, approximately 400,000 hectares and over 10,000 tons in 2017) (30). Likewise, seizures of heroin surmounted to 91 tons globally in 2016 (4). Opioids in general remain the most threatening drug as 34 million and 19 million individuals used opioids and opiates in the past year in 2016, respectively (4). As mentioned previously, all-cause mortality among individuals who regularly use heroin or have HUD is estimated to be 2.09 per 100-person years (95% CI=1.93, 2.26) and the standardized mortality rate to be 14.66 (95% CI=12.82, 16.50) (2). Worldwide, the greatest prevalence of opioid use disorder is seen in South Asia (n=4,331,000) (5). Age standardized 16 prevalence estimates suggest the greatest burden to be Australia at 0.46% (95% CI=0.41, 0.53) (5). In the US, the Centers for Disease Control and Prevention details that 948,000 individuals ages 12 and older used heroin in the last year (i.e., 0.4/100 persons) (6). Between 2002 to 2016 the number of active cases of heroin dependence has increased steadily with 2015- 2016 reaching 574,000 individuals with dependence (Table 2) (34). In 2016, there were nearly 15,500 fatal heroin-related overdose deaths (i.e., 5/100,000 American) (Table 3). From 2015 to 2016 alone, the heroin overdose death rate increased approximately 20% (6). Table 2. Population Projections of Newly Incident Heroin Users and Dependence Year Pair Newly Incident Heroin NIHUs Transitioned to Dependence Users 104,000 2002-2003 114,000 2004-2005 98,000 2006-2007 150,000 2008-2009 162,000 2010-2011 163,000 2012-2013 149,000 2015-2016 Link: https://rdas.samhsa.gov/#/ Source: NSDUH Restricted Use Dataset. Newly incident heroin users: first use within 12 months of survey assessment. 26,000 17,000 26,000 39,000 63,000 57,000 52,000 Dependence Prevalence 179,000 213,000 244,000 288,000 349,000 433,000 574,000 17 Table 3. United States Overdose Deaths by Drug. Data from United States Center for Disease Control and Prevention, CDC Wonder. Link: https://www.drugabuse.gov/related-topics/trends-statistics/overdose-death-rates Source: National Institute on Drug Abuse, 2018. Drugs Involved in U.S. Overdose Deaths* - Among the more than 72,000 drug overdose deaths estimated in 2017*, the sharpest increase occurred among deaths related to fentanyl and fentanyl analogs (synthetic opioids) with nearly 30,000 overdose deaths. Source: CDC WONDER. Location: According to the National Surveys on Drug Use and Health (US), which are intended to be nationally representative samples, about 3,000 individuals ages 12 to 17 and 88,000 individuals ages 18 to 25 used heroin recently in 2016 (35). In the same year, 383,000 individuals ages 26 and older used heroin recently (35). Heroin use disorder (HUD) trends mirror the between age group comparisons with 1,000, 152,000, and 473,000 individuals having HUD in the respective age groups 12-17, 18-25, and 26 and older (35). HUD age group trends from 2002 to 2016 are depicted in Figure 4 below. 18 Figure 4. Description of Heroin Use Disorder in the Past Year among Individuals Aged 12 or Older, by Age Group: Percentages. Data from United States National Surveys on Drug Use and Health, 2002-2016. Link: https://www.samhsa.gov/data/sites/default/files/NSDUH-FFR1-2016/NSDUH-FFR1- 2016.pdf Source: Key Substance Use and Mental Health Indicators in the United States (35). Past epidemiologic research has suggested drug use is a phenomenon predominantly among males (22)(36)(37), yet as of late, studies have suggested otherwise for several drugs (e.g., alcohol) (38)(39)(40). Male and female prevalence of heroin use once agape, has narrowed respectively from 2.4 and 0.8 persons/1,000 in 2002-2004 to 3.6 and 1.6 persons/1,000 in 2011- 2013 (41). While both males and females have experienced an increase in heroin use, as of 2016 males age 25-44 experience the greatest burden of demographic subgroups with the highest death rate of 15.5/100,000 individuals (6). Additional location variations in heroin use are seen by urbanicity with larger more urban counties experiencing higher age-adjusted heroin overdose death rates. That is, in 2016 large metropolitan counties with populations of one million or more individuals experienced 5.3 and 19 6.1 deaths/100,000 in central and fringe areas, repetitively (6). Whereas micropolitan counties with populations of 10,000 to 50,000 individuals experienced 3.6 deaths/100,000 (6). Likewise, metropolitan and non-metropolitan counties of various populations fall within a respective gradient. Variations in heroin overdose death rates by ethnic self-identification depict non- Hispanic white individuals as experiencing the largest death rates (42). While individuals of all ethnicities have experienced increases in heroin use and related outcomes, the largest increases have been for non-Hispanic whites (6)(42). Causes & Mechanisms: To study heroin use and related outcomes (e.g., dependence, overdose) causal agents, relatively distal correlates, and the circumstances and processes must be considered. By far, the strongest risk predictor of heroin use identified by epidemiologic research and subsequently emphasized by the media is prior prescription opioid use and the like (e.g., opioid use disorder) (6)(43)(44). Other suggested risk predictors include poly-drug use or dependence – excluding opioid pain relievers, compared to no past year use or drug use disorder, past year cocaine use or use disorder has the strongest association to heroin use disorder with an adjusted odds ratio of 14.7 (95% CI = 7.4, 29.2)(44). In other words, cannabis, alcohol, and psychotherapeutic drugs increase the risk of heroin use and use disorder, but have a lower associated risk than cocaine and prescription opioids (44). Related yet more distal etiologic correlates of heroin use may include psychiatric comorbidities such as depression and anxiety disorders, chronic pain, childhood trauma or adverse experiences, and neighborhood poverty (45)(46)(47)(48) (49). The natural history of heroin use disorder has not been thoroughly detailed based on the current study’s literature review. Among all drug use disorders, that of heroin has the highest burden of disease with mortality rates comparable to that of the elderly (50). Notably, the risk of heroin use disorder within 12 months of first using the drug has been estimated to be 20 approximately 30.2% (95% CI = 22.9, 37.5) (Figure 5) (51), which is almost as large as corresponding risk estimates for tobacco products. This large HUD probability for heroin has a parallel in animal models. Across several different strains for rat models, the animals will self- administer heroin, as is the case for non-human primates (52). Figure 5. Probability of Transition from Heroin First Use to Dependence within One Year. Data from United States National Surveys on Drug Use and Health. Link: https://www.drugabuse.gov/related-topics/trends-statistics/overdose-death-rates Source: JAMA Psychiatry, 2018. Prevention & Control: As the US continues to experience the current opioids crisis, prevention and control continue to be at the forefront of public health initiatives. Medication assisted treatment such as methadone, buprenorphine, and suboxone play an important role in treating heroin use disorder, along with naloxone for emergency overdose reversal (53). Additionally, medication assisted treatment should be coupled with counseling (e.g., cognitive behavioral therapy) to increase the likelihood of better health outcomes (41)(53). 21 To shift to a more nuanced review of public health in the face of the opioids crisis, the US federal government is a crucial structural component of the HUD treatment. Syringe services programs are aimed to control infectious disease (e.g., human immunodeficiency virus) spread among injection drug users. As of 2016, the federal ban on such harm reduction programs has been lessened and funds have been directed towards the opioids crisis (54). Yet, there is still a tangible need for more money to be directed to community-based harm reduction programs. Distal prevention and control methods have also included stricter opioid prescribing policies, the elimination of pain as a vital sign, and improved chronic pain management (28). Public health should consider increasing citizen science programs, which aims to connect researchers and citizens for crowdsourcing, program implementation, and community-tailored interventions (55). 2.5 Significance and Purpose Upon literature review, there is currently no available epidemiologic work detailing HUD as disaggregated indicators of the latent construct to assess the pairwise associations and measurement equivalence across subgroups. This study is also the first to investigate whether heroin use onset precipitates excess risk of stimulant use onset. Conclusions drawn from this work will provide a more in-depth understanding of HUD as a syndrome (via paired combinations of potential symptoms) and as a dimension (via the latent structure analysis). It will illuminate whether a DSM-IV-based instrument for measuring HUD is comparable for both sexes and for those with a history of EMPOU. Additionally, conclusions drawn from estimating risk of stimulant onset based on heroin onset will be useful in beginning to identify vulnerabilities associated with heroin use. Said information will shed light on the natural history of HUD for more informed public health secondary and tertiary intervention strategies. The current study is targeted at understanding the “how?” or mechanisms of HUD epidemiology – that is, what sequence of conditions or processes lead to the development of 22 HUD (32). The opioids crisis continues to be on an upward trend and has become more severe with the increasing presence of heroin adulterated with synthetic opioids such as fentanyl. Increased mortality and morbidity are concerning and will continue to be public health concerns until interventions can effectively prevent and control the epidemic. 23 CHAPTER 3 MATERIALS – NATIONAL SURVEYS ON DRUG USE AND HEALTH 3.0 Chapter Overview This chapter is organized into a standard set of sections for epidemiology research reports, beginning with a specification of a study population in conceptual terms (as opposed to strictly operational or sampling terms). Next, the cross-sectional design and multi-stage area probability sampling approach are described briefly, with a citation on more detailed online methods monographs. A section on human subjects’ protection procedures describes consent of the participants (and assent/consent for minors), with a paragraph on implications for participation levels. The next sections address levels of participation, year by year, and an apparent decline in those levels over time, which deserves discussion in later sections, as well as assessment procedures for the main constructs under study. The final section of the chapter provides an introduction to the use of analysis weights that account for both selection probabilities and also post-stratification adjustments to US Census distributions. It then describes issue of variance estimation and the several approaches used to account for non-independence of observations in complex survey designs of the type used here. Then, a final set of paragraphs provide an overview of the statistical approaches in the form of cross-classification and contingency table analyses, the analysis of survey data for case-crossover research when there are analysis weights involved, and the multivariate statistics required for study of dimensionally distributed levels of heroin problems when there is uncertainty about measurement equivalence across subgroups (e.g., males versus females). A final section of the chapter described the analysis software used for this project and provides appropriate citations. 3.1 The Population Under Study Chapter 2 has described global dimensions of heroin’s distribution across boundaries of multiple countries. Nonetheless, access to epidemiological data on heroin is more constrained 24 when parameters of data quality are taken into account (56). For this reason, this dissertation research project specifies a study population that consists of all United States dwelling unit residents of the 50 states and the District of Columbia, excluding those who are residents of institutional group quarters such as prisons and long-stay hospitals, as well as infants and children under age 12 years. This study population of non-institutionalized US residents can be sampled more or less rigorously by using multi-stage area probability sampling methods that start with state-level sampling frames. Institutionalized residents have been omitted for a combination of logistical reasons. These reasons include difficulty accessing prison and long- stay hospital patient populations, informed consent constraints, and other impediments to institutional sample surveys of the type described in connection with the Epidemiologic Catchment Area (ECA) research on institutional and non-institutional populations in five US metropolitan areas, conducted more than 25 years ago (53). Infants and children have not been included due to the relatively low attack rates for self- administration of heroin and other drugs at these ages. If bioassays are used, there might be a rationale for including young people (e.g., newborns exposed in uterus). In this project, no bioassays have been used. Others left out of these samples of national population surveys include migrants and others described as ‘homeless’ persons who are not regular residents of non-institutional group quarters such as the homeless shelters. Here again, there are logistical difficulties when one seeks to integrate data on these ‘no conventional residence’ population members with data on residents of conventional group quarters, as described when the ECA surveys studied ‘homeless’ individuals without a fixed abode (57). Additional information about issues of this type are described in the next section of this chapter, on sampling procedures. In addition, the exclusion of heroin users who are in the US 25 study population but not included in the multi-stage area probability samples is a topic for the Discussion sections of this project report. These sections follow presentation of the dissertation estimates and represent examples of limitations of the dissertation research project that require ‘mixed methods’ research approaches in future investigations (58). 3.2 Cross-Sectional Survey Design and Probability Sampling Approach The specified US population has been studied using a cross-sectional survey design with sampling and assessment procedures that make it possible to secure time sequences of events and processes that ordinarily are not considered in cross-sectional survey analyses. The Assessment section of this chapter provides more information about these time sequences and how they have been used for this project. The sampling approach and survey procedures for data collection have been designed by the sampling statisticians, epidemiologists, and other scientists employed by the US federal government for completion of the US National Surveys on Drug Use and Health (NSDUH). The NSDUH team also forged data sharing agreements and produced analysis-ready datasets that have made this dissertation research project possible. A detailed methods report on sampling is available online. Here, in brief, it can be summarized as follows, but interested readers will find useful details in the online reports (59): https://www.datafiles.samhsa.gov/study- publication/nsduh-2002-methodological-resource-book-mrb-nid14370) 3.3 Human Subjects Protection Field interviewers (FIs) are IRB trained on objectives such as ethics, human subjects research, the IRB’s role, and the role of FIs in protecting participants’ rights. Additional FI training includes Confidential Information Protection and Statistical Efficiency Act (CIPSEA), records management training, and bilingual training for FIs who are bilingual. After one month of field work, FIs continue training to understand sampling procedures in order to protect 26 sampling integrity, challenging field situations, screening and interview procedures, how to answer respondent questions, and an overall quarterly review of project procedures and protocols. All new FIs must pass certification. FIs are trained to identify unlisted dwelling units, which are then entered into computer and selected for participation (60). When FIs struggled to obtain participation of a dwelling unit, refusal conversion procedures were in place which centered on professional answering of questions, conversion letters, returning to the dwelling unit at another time. FI assess drug use and dependence using DSM-IV criteria via institutional review board approved protocols for recruitment and standardized computer-assisted self-interviews The US Department of Health and Human Services Center for Behavioral Health Statistics and Quality generated the NSDUH open access analysis files with de-identified data after applying disclosure analyses designed to prevent re-identification of participants. Given the circumstances of open access and no contact with participants, the Michigan State University institutional review board ruled that plans to analyze these data qualified for the federal category “not human subjects research.” 3.4 Participation Rates and Assessment Protocol Screening response rates were calculated based on a numerator of completed screenings and a denominator of total eligible dwelling units (Figure 7. Declining Response Rates - National Surveys on Drug Use and Health 6). Conditional interview response rates were calculated with numerators of completed interviews and denominators of the number of eligible respondents chosen through screening. Ineligible respondents were subtracted from the total. The unconditional interview response rate was calculated based on numerators of completed interviews and denominators of those that would have been eligible to be interview if all dwelling units had been screened properly. Overall response rates are based on the screening 27 response rate multiplied by the interview response rate. To maximize response rates participants receive $30 for completing the survey. Participation levels are generally between 65-70%. Year by year, response rates have declined yet compared to other federally funded national surveys rates for NSDUH are relatively large (Figure 7) (61). Non-response can be problematic if individuals who are newly incident heroin users are more likely to not participate. Research conducted in 1999 suggested that populations with high non-response rates do not always have high rates of drug use (61). While this research has not been replicated in recent years, it is hypothesized that sources of bias most likely cancel each other out. Possible explanations for declining response rates may include increasing number of two- worker households, longer commuting times, increased prevalence of caller ID, and increased number of federal surveys. Another potential explanation is decreased survey effort due to increased survey costs (61). 28 Figure 6. Declining Response Rates of Federally-Funded National Surveys Source: “Declining response rates in Federal Surveys: Trends and Implications” (June 2016), Mathematic Policy Research – Final Report Volume 1. (61) Link: https://aspe.hhs.gov/system/files/pdf/255531/Decliningresponserates.pdf 29 Figure 7. Declining Response Rates - National Surveys on Drug Use and Health Conditional Interview Unconditional Interview 72.0 71.1 57.6 55.5 Survey Year 2015a 2016 a Screening 80.0 78.1 Source: “Declining response rates in Federal Surveys: Trends and Implications” (June 2016), Mathematic Policy Research – Final Report Volume 1. (61) Link: https://aspe.hhs.gov/system/files/pdf/255531/Decliningresponserates.pdf aSource: National Surveys on Drug Use and Health: Methodological Resource Book Section 8. Link: https://www.samhsa.gov/data/sites/default/files/NSDUHmrbDCFR2016.pdf 3.5 Statistical Analysis NSDUH does not conduct a census of the population, thus sampling error is possible. To combat this possibility, large samples and probability sampling methods are utilized. Taylor Series Linearization is used for calculus-based variance and standard error estimation based on the complex survey design. A SUDAAN software for Statistical Analysis of Correlated Data package is used for such calculations. 30 To ensure collected data reflect the target population analysis weights were introduced. Analysis weights are based on the inverse probability of selection and account for the multi-stage design which included steps below. Related post-stratification adjustment corrected non- response, known population control totals, and extreme weights (62). (1) Adjustment of household weights for nonresponse at the screener level. (2) Post stratification of household weights to meet population controls for various household-level demographics by state. (3) Adjustment of household weights for extremes. (4) Post stratification of selected person weights. (5) Adjustment of responding person weights for nonresponse at the questionnaire level. (6) Post stratification of responding person weights. (7) Adjustment of responding person weights for extremes. 31 CHAPTER 4 MANUSCRIPT 1 – THE NATURAL HISTORY OF HEROIN USE DISORDER EXPLAINED BY PROBLEMS AND EXPERIENCES FROM FIRST MONTHS OF USE TO UP TO A YEAR AFTER ONSET 4.0 Abstract Background & Aim: Despite the United States’ history and continued experience with heroin use and related outcomes, little is known about the natural history of heroin use disorder (HUD). The current study aims to estimate the pairwise association between problems and experiences of heroin use disorder interval by interval from the first months of use. Methods: National Surveys on Drug Use and Health (NSDUH) 2002-2016 aggregated files include 837,326 participants with 876 newly incident heroin users (NIHUs) identified. The cross- sectional study was sliced to indicate time based on intervals between first months of heroin use to survey assessment. Problems and experiences (PE) to PE odds ratios were estimated using generalized linear model logistic regression by time intervals. Results: Within 0-90 days of first using heroin a robust association is seen between spending less time doing important activities and continued use despite problems with family or friends (OR=936.4, 95% CI=66.6, 13,164.9). By 330-390 days after first using heroin the strongest association is seen between spending a lot of time getting or using and continued use despite problems with family or friends (OR=441.3, 95% CI=43.4, 4,487.1). Discussion: Likely explanations for the robust point estimates and wide confidence intervals may reflect: 1) issues of sample size and small cell counts and 2) exchangeability between PE pairs. Conclusions: Soon after first using heroin there appears to be strong associations related to problems with personal relationships. Public health may benefit from engaging citizens in family prevention and intervention initiatives. 32 4.1 Introduction Heroin use is a global public health concern. In 2016 alone, 97 tons of heroin were seized globally (4). Specific to the US heroin, an estimated 0.4 per 100 persons have used in the past year in 2016 (6). In 2015 heroin-related overdoses reached about 26 per 100,000 persons and overdose deaths increased by five-fold from 2010 to 2016 (6). The opioid drug market has changed from its initial stages beginning in 1999. While extra-medical use of prescription opioids led to increased heroin use, and now the significant rise in synthetic opioids, there has still yet to be a departure from this upward trend (6). From a public health perspective, the increased use of heroin is troubling far beyond the direct mortality from heroin-related overdose. Heroin use disorder is associated with an estimated 40 years of life lost (50). Furthermore, other heroin use-related outcomes may include but are not limited to heroin use disorder (HUD), infections (e.g., Human Immunodeficiency Virus, Hepatitis C virus), psychiatric co-morbidities (e.g., depression), and low quality of life circumstances (e.g., homelessness) (63)(64). In tandem with the opioids crisis, the incidence of hepatitis C and other infections have increased (65)(66). In 2015 the economic burden of HUD was estimated to be roughly $51.2 billion which spanned crime, incarceration, chronic infectious diseases, treatment, neonatal abstinence syndrome, lost productivity, and overdose deaths (67). To meet the DSM-5 case definition for HUD only two criteria are necessary of the eleven possible: 1) using longer than intended or in larger amounts, 2) trying to cut down, 3) spending a lot of time getting/using/recovering, 4) unable to keep important commitments, 5) use affects personal relationships, 6) unable to do important activities, 7) use puts individual in physical danger, 8) physical or emotional problems, 9) tolerance develops, 10) withdrawal symptoms, 11) craving. 33 The current opioids epidemic is not the first of its kind in the US. After the passage of the 1914 Harrison Act, which put federal restrictions on opiate and coca products, heroin use became popular as individuals using once using widely available narcotics turned to illegal means of obtaining opioids (11). During the 1950s heroin was relatively inexpensive which led to an increase in use; naturally the price inflated with demand (11). Again the US struggled with heroin use associated with the US soldiers’ return from Vietnam in the early 1970s (25)(26). When considering all of the epidemiological studies on the natural history of heroin use disorders, one of the most influential studies was completed during the mid-1970s by a research team at the Washington University at Saint Louis. Led by the late Professor Lee N. Robins, the team was commissioned to investigate the fate of veterans who had returned from Vietnam and to estimate how often they had returned to use of heroin or other opioids in their home communities. This influential research dispelled commonly accepted beliefs about the natural history of heroin use and ‘addiction’ to heroin. Its evidence indicated an important fact: there was very low recurrence of heroin use or heroin use disorders among the veterans who had tried heroin in Southeast Asia. Instead, heterogeneity of post-return outcomes was found, often linked with individual-level susceptibilities, and sometimes with characteristics of communities in which the veterans were living (Table 4). Prominent among the predictors of recurrent heroin use were: (1) a history of non-opioid drug use, (2) peers’ use of drugs, and (3) long-standing histories of early ‘deviant’ or other socially maladaptive behaviors often grouped under the DSM heading of ‘anti-social personality disorder’ (68). Most importantly, what is known about heroin use is that everyone who uses will not go on to experience HUD. The most recent HUD research suggests 23 to 38% of newly incident heroin users develop HUD within about a year of onset (69). Based on literature review for the 34 current study, little is known about the progression of HUD. That is, after first use when HUD is possible but is still subclinical, what are the first clinical features that become apparent? The general goal of the current study is to investigate the development of heroin use disorder shortly after an individual starts to use heroin. Specifically, in addition to estimating occurrence rates for individual heroin problems and experiences (PE), the aim is to estimate the degree to which paired combinations of these heroin PE co-occur, interval by interval during the first months after first heroin use (Table 5)1. 1 Withdrawal symptoms included in questionnaire:1) feeling kind of blue or down, 2) vomiting or feeling nauseous, 3) having cramps or muscle aches, 4) having teary eyes or a runny nose, 5) feeling sweaty, having enlarged pupils, or having body hair standing up on your skin, 6) having diarrhea, 7) yawning, 8) having a fever, and 9) having trouble sleeping. 35 Table 4. Contrast of Heroin Knowledge Based on Lee Robins’ Study of Vietnam Veterans Return to the United States. Contradictory Evidence - After returning to the US, 8% of veterans used heroin and less than half of them used more than once a week for a month or more. - Heroin purchased in the US did not lead to a use disorder any more than cannabis or amphetamine did. - Heroin was considered to be the “main drug” - The majority of heroin users uses other drugs of 10% of users. and alcohol. Before L. Robins’ Study 1. Heroin use rapidly transitions to HUD. 2. Heroin use replaces the use of other drugs. 3. HUD is likely permanent without prolonged treatment. 4. Recovery from HUD requires abstinence. 5. Heroin use constitutes a major social problem. - After returning to the US, 1% experienced HUD during the first year back from Vietnam; 2% after the second or third year back. - Since returning, 12% of veterans experienced HUD relapse. - Less than half of the veterans used heroin upon returning and 1/8th experienced HUD. - Veterans who used heroin did experience more social problems (e.g., unemployment) than the rest of the sample, but given the majority used more drugs than heroin it cannot be concluded heroin is responsible for the problems. Source: “Vietnam Veterans Three Years after Vietnam: How Our Study Changed Our View of Heroin”, Robins et al., 2010. Link: Of the 14,000 enlisted men that returned from Vietnam in 1971, a random sample totaling 617 were followed for three years. Those who tested positive for drugs were oversampled. 36 Table 5. Description of Problems and Experiences of Heroin Use Disorder Included in the Diagnostic and Statistical Manual. Data from United States National Surveys on Drug Use and Health, 2002-2016. work, or school? have put you in physical danger? using heroin? wanted? by your use of heroin? “During the past 12 months… “ Problems & Experiences were probably caused or made worse by your use of heroin? important activities (spending time with friends & family)? have problems with your emotions, nerves, or mental health? PE # 1 Did you try to set limits on how often or how much heroin you used? 2 Did you have any problems with your emotions, nerves, or mental health that 3 Was there a month or more when you spent a lot of your time getting or 4 Did you need to use more heroin than you used in order to get the effect you 5 Did you have any problems with family or friends that were probably caused 6 Did using heroin cause you to give up or spend less time doing these types of 7 Did using heroin cause you to have serious problems like this either at home, 8 Did you cut down or stop using heroin at least one time? 9 Did you continue to use heroin even though you thought it was causing you to 10 Did you regularly use heroin and then do something where using heroin might 11 Did you continue to use heroin even though you thought it caused problems 12 Were you able to keep to the limits you set, or did you often use heroin more 13 Were you able to cut down or stop using heroin every time you wanted to or 14 Did you have 3 or more of these symptoms after you cut back or stopped 15 Did using heroin cause you to do things that repeatedly got you in trouble with 16 Did you have 3 or more of these symptoms at the same time that lasted for 17 Did you notice that using the same amount of heroin has less effect on you 18 Was there a month or more when you spent a lot of your time getting over 19 Did you have any physical problems that were probably caused or made 20 Did you continue to use heroin even though you thought it was causing you to NA Craving NSDUH Downloadable Public Use Dataset. *See footnote above for list of symptoms. longer than a day after you cut back or stopped using heroin?* tried to? using heroin?* the law? with family or friends? than you intended to? worse by using heroin? have physical problems? that it used to? the effects of the heroin you used? DSM IV 5 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 37 4.2 Methods Chapter 3 provides an overview of materials and methods for this sub-project of the dissertation research. Interested readers are referred to that chapter for information about the study population for the US National Surveys on Drug Use and Health, 2002-2016, sampling and recruitment, assessments, and basic details about statistical analyses. Sample: Aggregate NSDUH files included 837,326 participants, with 896 identified as newly incident heroin users (NIHUs) from survey years 2002-2016. All NIHUs were assessed one to 12 months after first heroin use, excluding all past users. Observations with missing month of first use were dropped resulting in 876 NIHUs (described further in Statistical Analyses section) (Figure 8). The analytic sample of 876 NIHU was made up of 465 males with the majority of NIHUs within 18-25 years of age, and white ethnic self-identification (Table 7). Most NIHUs has a history of extra-medical use of prescription pain relievers (i.e., prescription opioids) within 12 months of survey assessment (n=667). Statistical Analyses: Time between first use and survey assessment was calculated based on available month and year of first use minus the year quarter of survey assessment. Participants’ month of survey assessment is not available NSDUH public use files, so the year quarter yields three months of uncertainty in elapsed time between first use and assessment (i.e., possible 30-90-day discrepancy in time between first use and assessment). To aid in interpretation, imposed assumptions include: 1) survey assessment occurred on the 15th of the mid-quarter month and 2) day of first occurred on the 15th of the month. This elapsed time was categorized as ‘lag-time’ intervals, coded a categorical variable (Table 6). To account for the multi-stage complex sampling of the NSDUH, estimates used analysis-weights with variances calculated using Taylor Series linearization. Variance estimation 38 was set to single unit centered to produce standard errors based on the grand mean for the most conservative estimation. Analyses were repeated without analysis-weights and are available in the Appendix B – Manuscript 1. Stata SE 12.1 was used to carry out all statistical analyses. HUD was assessed using 20 questions about heroin problems and experiences (PE) as described by each newly incident heroin user – i.e., these are self-characterized problems and experiences with no information from parents, spouses, partners, employers, or other key informants. Some of the PEs would qualify as HUD ‘symptoms’ if a diagnosis of HUD could be established and confirmed. However, it would be a mistake to characterize each PE as an ‘HUD symptom’ in the absence of a diagnosed HUD because some experiences do not have the quality of a ‘symptom.’ A good example involves the experience of spending a lot of time getting heroin. Consider a newly incident user who has tried heroin one time, found the experience to be reinforcing, and had to spend a lot of time tracking down and getting a second dose. This NIHU might answer ‘Yes’ to the NSDUH question about spending a lot of time ‘getting’ heroin, but at this stage of progression beyond heroin onset, the context is not one of a heroin use disorder experience that is being manifest as a symptom. Rather, it is just an ‘experience’ in the life of the user, and the user might or might not consider it to be a ‘problem.’ Other PE most likely would qualify as ‘symptoms’ when they occur. For example, any NIHU who has experienced three or more withdrawal symptoms most likely is describing a clear symptomatic manifestation of the underlying pathological processes described in the early descriptions of ‘heroin addiction’ of the late 19th century. PE-specific proportions are estimates of PE attack rates with an implicit time dimension based on the lag-time interval. These proportions have been estimated based on ratios. Numerators for the ratio are participants who have experienced with the designated PE. The ratio’s denominator is the total number of all NIHUs, interval by interval (Table 4). 39 The NSDUH survey design relies on “gated” questions to minimize participants’ time needed to complete the survey, which results in some participants not being asked all 20 PE questions (see figure in Appendix B – Manuscript 1). To stabilize the denominator of PE-specific proportions, gated questions were re-coded to allow a stable denominator of all NIHU for each PE (n=876). Responses including “Don’t Know” or “Refused” were coded as “No”. As an example, 876 NIHUs were asked a primary question of: “Did you try to set limits on how often or how much heroin you would use?” The 147 NIHUs that responded “yes” were asked a secondary question: “Were you able to keep to the limits you set, or did you often use heroin more than you intended to?” Thus, the secondary question was re-coded to use a denominator of the 876 NIHUs that were asked the primary question. In order to quantify the degree of association linking PE-PE pairs, a generalized linear model with the logistic link function was used (i.e., logistic regression). Via these logistic regression models, the strength of association linking each PE pair might be inverse (i.e., with estimated regression beta < 0.0, exponentiated for an OR < 1.0) or might be positive (i.e., with estimated regression beta >0.0, exponentiated for an OR > 1.0). The OR estimator has been used because it is not margin-dependent. Other statistical indices of agreement and association such as kappa or correlation coefficients would depend upon the marginal frequencies of the PE. A margin-dependent estimator for degree of association or agreement is not useful in a study of natural history across intervals of elapsed time from an infection or exposure in the direction of sub-clinical and clinical disease processes because it is typical for manifestations of the pathological process to increase in their frequency across units of elapsed time. In consequence, an increasing correlation coefficient for a PE-PE pair might reflect a shift in the marginal frequency of each PE, with no shift in the degree of association. 40 The decision about which PE to place on the Y-side of the regression equation versus on the X-side of the regression equation is irrelevant in this context. It does not matter. The estimated logistic regression beta coefficient (and OR = exponentiated beta) will be the same, irrespective of which PE is on the Y-side or the X-side of the equations. The work of the dissertation research project included writing software programs to derive the estimated odds ratios, with due attention to the analysis weights and to the use of Taylor series linearization for variance estimation and derivation of 95% confidence intervals and tests of statistical significance via p-values. The programming was facilitated via Stata software ‘svy subpop’ commands. These commands were devised to produce PE to PE ORs for each of the 13 lag-time intervals. In addition, sensitivity analyses were completed using pseudo-lag-time intervals created by collapsing lag-time intervals one through three, seven through eight, and 12 through 13, with all other intervals considered ‘missing’ in order to produce non-overlapping elapsed time intervals. This additional set of analysis steps is helpful because the result is a set of non- overlapping NIHU (i.e., each NIHU is assigned to one and only one interval bin), and there is no covariance issue to be addressed when one seeks to compare estimates for one interval versus another. A note about the size of the odds ratio estimates may be in order. Epidemiologists studying exposure-disease relationships typically encounter OR estimates across a range from 0.10 through 10.0, with 0.1 for a strong inverse association under 1.0 and with 10.0 being a strong association above 1.0. In this study of natural history and the process of becoming a case of HUD, the relationships of interest are not exposure-disease relationships. Rather, they pertain to inter-relationships of individual features of the process that leads from first heroin use toward becoming a case of heroin use disorder. In this process, some of the PEs satisfy a condition of 41 exchangeability of the type that is seen when education researchers construct tests of arithmetic ability, with one item Q1 asking “2+2=?” and another item Q2 asking “1+1=?). Most students with decent arithmetic ability will answer both Q1 and Q2 correctly, and the students who correctly answer just one item might have been guessing when they answered. Students who do not have arithmetic ability will give incorrect answers to both Q1 and Q2. The result will be a very large association in the Q1-Q2 contingency table, with an odds ratio most likely well above 100. A similar phenomenon can be observed when a diagnostic test for a drug use disorder includes exchangeable items as in the case of ‘getting less of an effect when using the same dose’ cross-classified with ‘needing a larger dose to get the same effect.’ Both responses to PE items on these experiences are manifestations of subjectively-felt tolerance, and the estimated OR for these two items should be quite large, in a reflection of their exchangeability. For this reason, the use of the OR in this study produces some quite large OR estimates that are not typically seen in exposure-disease investigations, but that are quite often seen when epidemiologists study patterns of interdependent responses to exposure. As shown below, some of the estimated ORs are far beyond the values expected in studies of exposure-disease associations, but they are not exceptional in studies of interdependent manifestations of an observed disease process. 42 Figure 8. Flow of Participants in Newly Incident Heroin Use Case Ascertainment. Data from US, National Surveys on Drug Use and Health, 2002-2016. NSDUH – Year-Specific Files 2003 2004 2005 2006 2007 2008 2009 n=54,079 n=55,230 n=55,602 n=55,905 n=55,279 n=55,435 n=55,110 n=55,234 2012 n=55,268 2013 n=55,160 2014 n=55,271 2015 n=57,146 2016 n=56,897 2002 2010 2011 n= 57,313 n= 58,397 2002-2016 Aggregate Files NSDUH n= 837,326 Never Used Heroin n=825,420 Past Onset Heroin n=9,153 Newly Incident Heroin Users n=896 Newly Incident Heroin Users within Lag-Time Intervals 1-13 n=876 Missing Month of First Use n=20 NSDUH Downloadable Public Use Dataset. Unweighted counts (n). Newly incident heroin use: first heroin use within 12 months of survey assessment; past onset users excluded. Lag-time intervals indicate elapsed time between first use and survey assessment. Participants included in incident use due to year of first use information but missing month of first use were dropped from analytic sample due to inability to define participant’s lag-time interval between first use and survey assessment. 43 Table 6. Description of Lag-Time Intervals Indicating Elapsed Time Between Newly Incident Heroin Use and Survey Assessment. Data from United States National Surveys on Drug Use and Health 2002-2016. Lag-Time Interval Elapsed Time (days) Assumeda Possible 0-90 1-120 30-150 60-180 90-210 120-240 150-270 180-300 210-330 240-360 270-390 300-420 330-450 30 60 90 120 150 180 210 240 270 300 330 360 390 Without Overlapb 0-150 150-300 300-450 NSDUH Downloadable Public Use Dataset. aAssumptions include 1) survey assessment occurred on the 15th of the mid-quarter month and 2) day of first occurred on the 15th of the month. bIntervals without overlap drop observations in intervals 4-6 and 9-11 to increase certainty of time elapsed for sensitivity analysis. 1 2 3 4 5 6 7 8 9 10 11 12 13 44 Table 7. Characteristics of Overall Sample and Newly Incident Heroin Use Analytic Sample. Data from US, National Surveys on Drug Use and Health, 2002-2016. Aggregate NSDUH 2002-2016 n=837,326 n (%) NIHUs n=896 n (%) NIHUs Intervals* n=876 n (%) Demographic Characteristics Sex Age Groups (Years) Male 12-17 18-25 26-34 35-49 50-64 65+ 401,270 (48) 258,309 (10) 263,258 (13) 93,449 (14) 128,684 (25) 56,998 (22) 36,628 (16) 532,503 (67) 106,106 (12) 12,284 (<1) 4,042 (<1) 30,449 (5) 26,309 (1) 134,633 (14) 476 (62) 227 (15) 539 (47) 82 (22) 44 (14) 4 (2) 0 715 (81) 21 (4) 20 (<1) 8 (1) 5 (1) 31 (1) 96 (10) Ethnic Self-Identification White Black/African American Native American/Alaskan Native Native Hawaiian /Other Pacific Island. Asian >1 Ethnicity Hispanic Extra-Medical Prescription Opioid History Lifetime Use (>12 Mon.*) Within 12 Mon.* Never Used Missing Data NSDUH Downloadable Public Use Data. NIHUs: Newly incident heroin users first used heroin within 12 months of survey assessment. Past onset users excluded. Ethnic self-identification: all ethnicities other than Hispanic are specified as non-Hispanic per survey assessment. *More than or within 12 months of survey assessment. *within lag-time intervals Unweighted n; weighted %. 89,390 (11) 88, 649 (9) 608,112 (74) 51,175 (5) 93 (10) 677 (76) 112 (13) 15 (2) 465 (62) 221 (15) 528 (48) 82 (23) 42 (13) 3 (1) 0 699 (81) 20 (3) 19 (<1) 8 (1) 5 (1) 30 (2) 95 (10) 90 (9) 667 (77) 105 (11) 14 (2) 45 4.3 Results PE-Specific Attack Rates: Each estimated proportion shown in Table 8 can be conceptualized as an ‘attack rate’ with the time dimension implicit in the formulation of the rate, as would be the case in the estimation of food-specific attack rates for diarrhea, vomiting, fever, and other facets of food-borne illness investigated in the aftermath of a food-borne illness outbreak. That is, in these attack rates, the time dimension typically is implicit, and is not quantified in terms of person-days, person-weeks, or person-months. Table 8 shows PE-specific proportions across a broad range of estimates. For example, an estimated 40% of NIHUs had tried to set limits on heroin use (PE1), whereas no more than about one percent had the experience of ‘continuing to use despite physical problems.’ A quarter or larger of NIHUs experienced PE2-problems with emotions (31%), PE3-spending a lot of time getting or using (28%), PE4-needing more to get the same effect (27%), PE5- problems with family or friends (26%), or PE5-spending less time doing important activities (25%). PE to PE Odds Ratios by Lag-Time Intervals: As shown in Tables 9-10, within 0-90 days of first using heroin, some of the strongest associations between PE pairs include: PR6/PE11- spending less time doing important activities/continued to use despite problems with family or friends (OR=936.4, 95%CI= 66.6, 12,511.5), PE6/PE10-spending less time doing important activities/put in physical danger (OR= 873.7, 95% CI=70.8, 10,785.4), PE10/PE11- in physical danger/continued to use despite problems with family or friends (OR=871, 95%CI=60.6, 12,511.5), and PE3/PE6-spent a lot of time getting or using heroin/spending less time doing important activities (OR=556.2, 95% CI=38.5, 8,027.5). Within 1-120 days of first using heroin, some of the strongest associations between PE pairs include: PE9/PE13-continued to use despite having problems with emotions/was not 46 able to cut down (OR=551.7 95% CI=45.4, 6,700.4), PE9/PE14-cotinued to use despite having problems with emotions/had three or more withdrawal symptoms (OR=551.7 95% CI=45.4, 6,700.4), PE12/PE16-unable to keep limits/had three or more withdrawal symptoms at the same time (OR=514.8, 95% CI=36.7, 7220.3), and PE3/PE16-spent a lot of time getting or using heroin/had three or more withdrawal symptoms at the same time (OR=299.1, 95% CI=23.0, 3883.9) (Tables 11, 12). Within 30-150 days of first using heroin, some of the strongest associations between PE pairs include: PE17/PE18-same amount had less effect/spent a lot of time getting over the effects (OR=320.6, 95% CI=15.7, 6,536.7), PE9/PE17-continued to use despite having problems with emotions/same amount had less effect (OR=213.4, 95% CI= 16.3, 2,796.4), PE3/PE12-spent a lot of time getting or using/unable to keep limits (OR=166.4, 95% CI= 18.8, 1,472.5), PE15/PE19-trouble with the law/had physical problems (OR= 150.7, 95% CI= 6.6, 3,425.3), and PE15/PE20-trouble with the law/continued to use despite having physical problems (OR= 150.7, 95% CI= 6.6, 3,425.3) (Tables 13, 14). Within 60-180 days of first using heroin, some of the strongest associations between PE pairs include: PE3/PE7-spent a lot of time getting or using/caused you to have serious problems (OR=1,181.8, 95% CI=120.6, 11,582.3), PE7/PE15-caused you to have serious problems/trouble with the law (OR= 258.5, 95% CI= 33.7, 3,907.8), PE6/PE7-spent less time doing important activities (OR=258.5, 95% CI= 32.3, 2,066.4), and PE7/PE11-continued to use despite having problems with family or friends (OR=232.2, 95% CI= 24.3, 2.219.0) (Tables 15, 16). Within 90-210 days of first using heroin, some of the strongest associations between PE pairs include: PE9/PE10-cotinued to use despite having problems with emotions/physical danger (OR=331.9, 95% CI=35.7, 3,088.8), PE3/PE14-spent a lot time getting 47 or using/had three or more withdrawal symptoms (OR=196.5, 95% CI=19.2, 2,002.1), and PE4/PE6-needed more to get the same effect/spent less time doing important activities (OR=147.3, 95% CI= 22.5, 966.3) (Tables 17, 18). Within 120-240 days of first using heroin, some of the strongest associations between PE pairs include: PE4/PE13-needed more to get the same effect/not able to cut down (OR=319.8, 95% CI=30.3, 3371.0), PE4/PE14-needed more to get the same effect/had three or more withdrawal symptoms (OR=319.8, 95% CI=30.3, 3371.0), PE4/PE16-needed more to get the same effect/had three or more withdrawal symptoms at the same time, PE12/PE13-not able to set limits/not able to cut down (OR=301.0, 95% CI=28.0, 3,238.5), PE12/PE14-unable to set limits/had three or more withdrawal symptoms (OR=301.0, 95% CI=28.0, 3,238.5), and PE12/PE16-not able to set limits/had three or more withdrawal symptoms at the same time (OR=301.0, 95% CI=28.0, 3,238.5) (Tables 19, 20). Within 150-270 days of first using heroin, some of the strongest associations between PE pairs include: PE3/PE4-spent a lot of time getting or using/needed more to get the same effect (OR=1,008.0, 95% CI= 99.4, 10,219.5), PE11/PE15-continued to use despite having problems with family or friends/trouble with the law (OR=454.8, 95% CI=41.2, 5,019.9), and PE4/PE6-needed more to get the same effect/spent less time doing important activities (OR=50.0, 2,731.6) (Tables 21, 22). Within 180-300 days of first using heroin, some of the strongest associations between PE pairs include: PE11/PE12-continued to use despite having problems with family or friends/unable to set limits (OR=2,396.0, 95% CI=178.7, 32,117.4), PE11/PE13-continued to use despite having problems with family or friends/unable to cut down (OR=1,301.5, 95% CI=144.5, 11,721.8 ), and PE6/PE7-spent less time doing important activities/caused you to have serious problems (OR=1,293.5, 95% CI=86.6, 19,326.3) (Tables 23, 24). 48 Within 210-330 days of first using heroin, some of the strongest associations between PE pairs include: PE9/PE11-continued to use despite having problems with emotions/continued to use despite having problems with family or friends (OR=2,111.3, 95% CI=102.8, 43,376.5), PE2/PE5-had problems with emotions/had problems with family or friends (OR=342.0, 95% CI= 29.5, 3,964.4), PE2/PE4-had problems with emotions/needed more to get the same effect (OR=240.7, 95% CI=19.0, 1,030.4), and PE2/PE11-had problems with emotions/continued to use despite having problems with family or friends (OR= 238.4, 95% CI= 18.1, 3,145.3) (Tables 25, 26). Within 240-360 days of first using heroin, some of the strongest associations between PE pairs include: PE6/PE7-spent less time doing important activities/caused you to have serious problems (OR=514.8, 95% CI=52.5, 5,052.5), PE3/PE12-spent a lot of time getting or using/unable to keep limits (OR=401.5, 95% CI=39.5, 4,084.5), PE17/PE18-the same amount had less effect/spent a lot of time getting over the effects (OR=236.0, 95% CI=8.2, 6,776.6), PE6/PE15-spent less time doing important activities/trouble with the law (OR=155.1, 95% CI= 13.1, 1,839.0), PE7/PE15-caused you to have serious problems/trouble with the law (OR=147.7, 95% CI=12.4, 1,75.5), and PE11/PE15-continued to use despite problems with family or friends/trouble with the law (OR=133.0, 95% CI=11.2, 1,581.5) (Tables 27, 28). Within 270-390 days of first using heroin, some of the strongest associations between PE pairs include: PE6/PE7-spent less time doing important activities/caused you to have serious problems (OR=221.7, 95% CI=16.7, 2,940.9), PE11/PE13=continued to use despite having problems with family or friends/unable to cut down (OR=110.1, 95% CI=13.1, 925.9), and PE4/PE6-needed more to have the same effect/spent less time doing important activities (OR=99.5, 95% CI=11.3, 877.2) (Tables 29, 30). 49 Within 300-420 days of first using heroin, some of the strongest associations between PE pairs include: PE6/PE7-spent less time doing important activities/caused you to have serious problems (OR=261.8, 95% CI=28.3, 2,425.0), PE2/PE6-had problems with emotions/spent less time doing important activities (OR=217.6, 95% CI=25.4, 1,864.5), and PE6/PE10-spent less time doing important activities/physical danger (OR=115.1, 95% CI=8.3, 1,597.0) (Tables 31, 32). Within 390-450 days of first using heroin, some of the strongest associations between PE pairs include: PE3/PE11-spent a lot of time getting or using/continued to use despite having trouble with family or friends (OR=441.3, 95% CI=43.4, 4,487.1), PE1/PE2=tried to set limits/had problems with emotions (OR=377.7, 95%CI=46.7, 3,053.7), PE2/PE6-had problems with emotions/spent less time doing important activities (OR=371.1, 95% CI=32.7, 4,206.4), PE6/PE7-spent less time doing important activities/caused you to have serious problems (OR=286.1, 95% CI=26.0, 3,149.1), and PE3/PE6-spent a lot of time getting or using/spent less time doing important activities (OR=235.2, 95% CI=21.5, 2,567.2) (Tables 33, 34). Stratified by Analysis Weight Quartiles: In this study, an investigation of variation in the OR estimates across quantiles of analysis weights is needed to show what might have been observed if analysis weights had been ignored. For this reason, the analyses were repeated for each quartile of analysis weight. As graphically displayed, the PE to PE ORs stratified by analysis weight quartiles do not differ appreciably. The distribution of OR strength appears to be similar in each quartile. Sensitivity Analysis: Within 0-150 days of first using heroin, some of the strongest associations between PE pairs include: PE8/PE13-tried to cut down or stop using at least once/unable to cut down (OR=480.6, 95% CI=70.3, 3,286.2), PE12/PE16-unable to set limits/had three or more withdrawal symptoms at the same time (OR=416.7, 95% CI=35.8, 50 4,845.8), PE3/PE16-spent a lot of time getting or using/had three or more withdrawal symptoms at the same time (OR=127.4, 95% CI=18.1, 897.2), and PE2/PE16-had problems with emotions/had three or more withdrawal symptoms at the same time (OR=107.9, 95% CI=10.2, 1,140.8) (Tables 35, 36). Within 150-300 days of first using heroin some of the strongest associations between PE pairs include: PE5/PE7-had problems with family or friends/caused serious problems (OR=663.0, 95% CI=147.5, 2,979.8), PE3/PE11-spent a lot of time getting or using/continued to use despite having problems with family or friends (OR=523.2, 95% CI=56.0, 4,888.9), PE6/PE12-spent less time doing important activities/unable to set limits (OR=381.9, 95% CI=), PE7/PE11-caused serious problems/continued to use despite problems with family or friends (OR=289.5, 95% CI=58.4, 1,434.7), PE11/PE15-continued to use despite problems with family or friends (OR=242.0, 95% CI=25.9, 2,260.7), and PE6/PE7-spent less time doing important activities/caused serious problems (OR=208.1, 95% CI=37.9, 1,143.1) (Tables 37, 38). Within 300-450 days of first using heroin, some of the strongest associations between PE pairs include: PE3/PE11-spent a lot of time getting or using/continued to use despite having problems with family or friends (OR=558.3, 95% CI=64.9, 4,803.9), PE2/PE6-had problems with emotions/spent less time doing important activities (OR=273.5, 95% CI=57.4, 1,303.3), PE2/PE10-had problems with emotions/physical danger (OR=279.6, 95% CI=279.6, 95% CI=31.2, 2,503.0), and PE2/PE12-had problems with emotions/unable to set limits (OR=154.4, 95% CI=16.0, 1,487.0) (Tables 39, 40). 51 caused by your use of heroin? home, work, or school? or using heroin? effect you wanted? might have put you in physical danger? 40 Did you try to set limits on how often or how much heroin you used? 31 Did you have any problems with your emotions, nerves, or mental health that were probably caused or made worse by your use of heroin? 28 Was there a month or more when you spent a lot of your time getting 27 Did you need to use more heroin than you used in order to get the 26 Did you have any problems with family or friends that were probably 25 Did using heroin cause you to give up or spend less time doing these types of important activities (spending time with friends & family)? 23 Did using heroin cause you to have serious problems like this either at 22 Did you cut down or stop using heroin at least one time? 23 Did you continue to use heroin even though you thought it was causing you to have problems with your emotions, nerves, or mental health? 21 Did you regularly use heroin and then do something where using heroin 18 Did you continue to use heroin even though you thought it caused 17 Were you able to keep to the limits you set, or did you often use heroin 12 Were you able to cut down or stop using heroin every time you wanted 9 Did you have 3 or more of these symptoms after you cut back or 8 Did using heroin cause you to do things that repeatedly got you in 8 Did you have 3 or more of these symptoms at the same time that lasted for longer than a day after you cut back or stopped using heroin?* 6 Did you notice that using the same amount of heroin has less effect on 6 Was there a month or more when you spent a lot of your time getting 3 Did you have any physical problems that were probably caused or 1 Did you continue to use heroin even though you thought it was causing over the effects of the heroin you used? problems with family or friends? stopped using heroin?* trouble with the law? made worse by using heroin? you to have physical problems? more than you intended to? to or tried to? you that it used to? 238 228 231 195 192 185 170 163 148 135 105 76 68 67 39 38 25 11 876 876 876 876 876 876 876 876 876 876 876 876 876 876 876 876 876 876 Table 8. Description of Problems and Experiences of Heroin Use Disorder. Data from United States National Surveys on Drug Use and Health, 2002-2016. Problems & Experiences “During the past 12 months…” Proportionsa n. 356 246 d. % 876 876 NSDUH Downloadable Public Use Dataset. aUnweighted n: numerator & d: denominator; % weighted proportions. *See footnote above for list of symptoms. 52 Table 9. Weighted Odds Ratios of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 1: possible 0-90 days, assumed 30 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 53 Table 10 Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 1: possible 0-90 days, assumed 30 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 54 Table 11. Weighted Odds Ratios of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 2: possible 1-120 days, assumed 60 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 55 Table 12. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 2: possible 1-120 days, assumed 60 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 56 Table 13. Weighted Odds Ratios of Problem and Experience Pairs Within 30-150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not contain 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 3: possible 30-150 days, assumed 90 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 57 Table 14. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 90 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 3: possible 30-150 days, assumed 90 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 58 Table 15. Weighted Odds Ratios of Problem and Experience Pairs Within 60-180 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 4: possible 60-180 days, assumed 120 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 59 Table 16. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 60-180 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 4: possible 60-180 days, assumed 120 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 60 Table 17. Weighted Odds Ratios of Problem and Experience Pairs Within 150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 5: possible 90-210 days, assumed 150 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 61 Table 18. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 5: possible 90-210 days, assumed 150 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 62 Table 19. Weighted Odds Ratios of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 6: possible 120-240, assumed 180 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 63 Table 20. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 6: possible 120-240, assumed 180 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 64 Table 21. Weighted Odds Ratios of Problem and Experience Pairs Within 150-270 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 7: possible 150-270, assumed 210 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 65 Table 22. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150-270 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 7: possible 150-270, assumed 210 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 66 Table 23. Weighted Odds Ratios of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 8: possible 180-300, assumed 240 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 67 Table 24. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 8: possible 180-300, assumed 240 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 68 Table 25. Weighted Odds Ratios of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 9: possible 210-330, assumed 270 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 69 Table 26. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 9: possible 210-330, assumed 270 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 70 Table 27. Weighted Odds Ratios of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 10: possible 240-360, assumed 300 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 71 Table 28. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 10: possible 240-360, assumed 300 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 72 Table 29. Weighted Odds Ratios of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 11: possible 270-390, assumed 330 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 73 Table 30. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 11: possible 270-390, assumed 330 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 74 Table 31. Weighted Odds Ratios of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 12: possible 300-420, assumed 360 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 75 Table 32. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 12: possible 300-420, assumed 360 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 76 Table 33. Weighted Odds Ratios of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time interval 13: possible 330-450, assumed 390 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 77 Table 34. Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 13: possible 330-450, assumed 390 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 78 Figure 9. Odds Ratios with 95% Confidence Intervals of Problem and Experience Pairs Stratified by Analysis Weight Quartiles. Data from United States National Surveys on Drug Use and Health, 2002-2016 A. First Quartile (0 > x £ 61.8) B. Second Quartile (61.8 > x £ 134.1) 2,52,62,7 2,102,11 2,14 2,16 2,4 2,3 2,13 2,12 2,15 2,8 2,18 2,9 2,192,20 2,17 3,4 3,6 3,11 3,16 3,14 3,123,13 3,9 3,7 3,5 3,10 3,15 3,8 3,193,20 3,173,18 4,6 4,9 4,114,12 4,16 4,5 4,14 4,13 4,7 4,10 4,15 4,8 4,20 4,19 4,17 4,18 5,65,7 5,10 5,15 5,16 5,9 5,12 5,14 5,13 5,20 5,8 5,185,19 5,17 5,11 6,7 6,96,106,11 6,15 7,107,11 7,15 8,13 9,11 9,14 9,16 10,11 6,16 6,12 6,14 6,13 6,196,20 6,8 6,17 6,18 9,13 9,12 9,10 9,15 9,189,199,20 9,17 11,15 11,12 11,16 11,14 11,13 11,20 11,17 11,19 11,18 10,15 10,12 10,13 10,16 10,14 10,20 10,19 10,18 10,17 7,12 7,9 7,19 7,16 7,137,14 7,20 7,18 7,8 7,17 8,9 8,12 8,11 8,15 8,10 8,168,178,188,198,20 8,14 1,16 1,4 1,13 1,3 1,6 1,14 1,91,101,11 1,2 1,15 1,5 1,7 1,20 1,171,181,19 1,12 1,8 12,16 12,13 12,14 12,15 13,15 18,19 15,19 15,16 15,20 15,18 15,17 14,15 14,19 14,18 14,16 14,17 14,20 12,20 12,19 12,17 12,18 13,19 13,20 13,14 13,16 13,17 13,18 16,18 16,17 16,19 16,20 17,18 17,19 17,20 18,20 19,20 1 C. Third Quartile (134.1 > x £ 337.2) 6 Discordant Pair Odds Ratios by PE 16 11 21 1,13 1,3 1,14 1,4 1,16 1,6 1,15 1,9 1,2 1,101,11 1,7 1,5 1,171,18 1,8 1,12 1,191,20 2,10 2,3 2,6 2,16 2,11 2,4 2,7 2,14 2,12 2,5 2,13 2,15 2,8 2,18 2,17 2,9 2,192,20 3,4 3,63,7 3,93,10 3,123,133,14 3,16 3,11 3,5 3,15 3,8 3,17 3,19 3,18 3,20 4,64,7 4,9 4,114,124,134,14 4,16 4,10 4,5 4,15 4,8 4,19 4,17 4,20 4,18 5,65,7 5,95,10 5,15 5,16 5,13 5,12 5,14 5,8 5,195,20 5,11 5,175,18 6,7 6,96,106,116,12 6,16 6,15 6,14 6,13 6,8 6,20 6,176,186,19 7,9 7,11 7,15 7,10 7,12 7,16 7,14 7,13 7,8 7,20 7,177,187,19 8,13 9,109,11 9,16 9,14 9,12 10,11 10,13 10,14 10,16 10,12 12,13 12,14 12,16 11,12 11,13 11,16 11,14 9,13 10,15 11,15 13,20 8,10 8,118,12 8,9 8,15 8,20 8,14 8,168,178,188,19 9,15 9,179,189,199,20 12,15 12,19 12,18 12,20 12,17 13,19 13,15 13,14 13,16 13,18 13,17 14,20 14,15 14,19 14,17 14,16 14,18 10,20 10,17 10,18 10,19 11,20 11,17 11,18 11,19 17,18 15,19 15,20 15,16 15,17 15,18 16,17 16,18 16,19 16,20 17,19 17,20 18,19 18,20 19,20 1,16 1,131,14 1,3 1,4 1,6 1,18 1,5 1,9 1,2 1,7 1,101,11 1,15 1,19 1,8 1,12 1,17 1,20 2,6 2,5 2,11 2,10 2,3 2,4 2,12 2,7 2,13 2,16 2,14 2,18 2,15 2,8 2,17 2,9 2,192,20 3,4 3,113,123,133,14 3,6 3,16 3,9 3,10 3,5 3,15 3,7 3,8 3,19 3,173,18 3,20 4,13 4,114,12 4,14 4,6 4,5 4,9 4,16 4,7 4,10 4,15 4,8 4,18 4,19 4,17 4,20 5,65,7 5,10 5,9 5,12 5,18 5,13 5,16 5,14 5,19 5,17 5,8 5,11 5,15 5,20 6,7 6,9 6,11 6,12 6,10 6,15 6,20 6,13 6,16 6,14 6,8 6,186,19 6,17 7,11 8,13 9,11 10,11 10,15 11,15 12,13 12,14 12,16 7,15 7,10 7,9 7,20 7,12 7,19 7,18 7,13 7,17 7,14 7,16 7,8 9,10 9,12 9,16 9,13 9,14 9,15 9,179,189,199,20 8,12 8,15 8,9 8,11 8,20 8,10 8,168,178,18 8,14 8,19 10,20 10,12 10,14 10,16 10,13 10,19 10,18 10,17 12,20 12,15 12,17 12,19 12,18 11,13 11,12 11,19 11,16 11,14 11,18 11,20 11,17 15,20 15,19 15,16 15,18 15,17 14,15 14,18 14,17 14,16 14,19 14,20 13,15 13,18 13,14 13,16 13,19 13,20 13,17 17,18 18,19 16,18 16,17 16,19 16,20 17,19 17,20 18,20 19,20 1 D. Fourth Quartile (x > 337.2) 6 Discordant Pair Odds Ratios by PE 11 16 21 1,3 1,11 1,5 1,2 1,10 1,14 1,61,7 1,4 1,16 1,9 1,13 1,19 1,171,18 1,12 1,15 1,20 1,8 2,42,52,62,7 2,132,14 2,16 2,18 2,11 2,3 2,10 2,15 2,17 2,8 2,9 2,12 2,192,20 3,43,53,63,7 3,113,12 3,15 4,6 5,65,7 5,10 6,7 6,11 6,15 7,11 8,13 9,119,129,139,14 9,16 10,15 4,11 4,7 4,5 4,9 4,15 4,12 4,10 4,13 4,16 4,14 4,19 4,174,18 4,20 4,8 3,9 3,10 3,13 3,16 3,14 3,17 3,19 3,8 3,18 3,20 6,9 6,13 6,10 6,14 6,16 6,12 6,20 6,176,18 6,8 6,19 5,16 5,13 5,9 5,15 5,12 5,14 5,19 5,17 5,8 5,18 5,11 5,20 7,10 7,13 7,9 7,14 7,16 7,12 7,20 7,17 7,8 7,187,19 7,15 10,11 10,16 10,14 10,13 10,12 10,19 10,18 10,17 10,20 9,18 9,10 9,17 9,15 9,199,20 8,17 8,188,198,20 8,9 8,118,12 8,10 8,148,158,16 11,13 11,16 11,14 11,15 11,12 11,19 11,17 11,20 11,18 12,16 12,14 12,13 13,20 13,18 13,17 13,19 13,14 13,16 13,15 12,15 12,17 12,18 12,19 12,20 14,20 14,18 14,17 14,19 14,15 14,16 15,17 15,18 15,16 15,19 15,20 16,20 16,17 16,19 16,18 17,18 17,19 17,20 18,19 18,20 19,20 21 1 16 6 Discordant Pair Odds Ratios by PE 6 Discordant Pair Odds Ratios by PE 11 NSDUH Public Use Dataset. Odds ratios and 95% confidence intervals produced from generalized linear model logistic regression. X-axis: PE pairs. Y-axis: OR and 95% CI values. Lag-intervals 1-13 collapsed. Analysis weights use Taylor Series Linearization for calculus-based variance estimation. Upper-bound confidence intervals ³20 capped at 20; corresponding point estimates capped at 20. 16 11 21 40 30 20 10 0 40 30 20 10 0 1 40 30 20 10 0 40 30 20 10 0 79 Table 35. Sensitivity Analysis: Weighted Odds Ratios of Problem and Experience Pairs Within 0-150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time intervals 1-3: possible 0-150 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 80 Table 36. Sensitivity Analysis: Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 0-150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time intervals 1-3: possible 0-150 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 81 Table 37. Sensitivity Analysis: Weighted Odds Ratios of Problem and Experience Pairs Within 150-300 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time intervals 7-8: possible 150-300 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 82 Table 38. Sensitivity Analysis: Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150-300 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 7-8: possible 150-300 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 83 Table 39. Sensitivity Analysis: Weighted Odds Ratios of Problem and Experience Pairs Within 300-390 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. *Statistically significant: 95% confidence interval does not include 1.0. Values of 1.0 indicate null associations or inability to calculate OR. Lag-time intervals 12-13: possible 300-390 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 84 Table 40. Sensitivity Analysis: Weighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 300-390 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 12-13: possible 300-390. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 85 4.4 Discussion There is tangible evidence that heroin use disorder syndrome begins to form within months of first using heroin. This is made evident by the incidence of PE pairs which qualify as a mild case of DSM HUD. What is unique to this study is the slicing of cross-sectional survey assessment data into increments of increasing lengths of time participants would have had to develop HUD. The natural history of HUD is illustrated by PE pair associations that show clinical features’ coalescence over time. Within the first months of using heroin for the first time the most prominent associations relate to having use affect personal relationships, physical danger, and ability to do important activities. Any two of these PEs alone are enough to make a DSM-5 diagnosis of HUD. Having a PE of spending less time doing important activities is associated with continuing use despite problems with family or friends (OR=936.4, 95% CI=66.6, 13,164.9). A PE of spending less time doing important activities is associated with physical danger (OR=873, 95% CI=70.8, 10,785.4) and physical danger is associated with continuing to use despite problems with family or friends (OR=871, 95% CI=60.6, 12,511.5). Point estimates are robust and 95% confidence intervals are statistically significant. Within 1-120 days of first using heroin the HUD syndrome appears to form through the coalescence of continued use despite emotional problems, being unable to cut down, being unable to set limits, and having withdrawal syndrome symptoms. Pair-wise combinations tend to have robust associations: Continued use despite problems with emotions/unable to cut down (OR=551.7, 95% CI=45.4, 6,700.2); continued use despite problems with emotions/having three or more withdrawal symptoms (OR=551.7, 95% CI=45.4, 6,700.2); unable to set limits/having three or more withdrawal symptoms (OR=514.8, 95% CI=36.7, 7,220.3). 86 From 30-150 days of first heroin use prominent associations are seen among PE such as signs of tolerance, continued use despite problems with emotions, withdrawal symptoms, unable to set limits, and physical problems. The strongest combination is between the same amount having less effect (i.e., signs of tolerance) and spending a lot of time getting over the effect (OR=320.6, 95% CI=15.7, 6,536.7). Additionally, continuing to use despite problems with emotions and the same amount having less effect (OR=213.4, 95% CI=16.3, 2,796.4), spending a lot of time getting or using and unable to set limits (OR=166.4, 95% CI= 18.8, 1,472.5), and trouble with the law and physical problems (OR=150.7, 95% CI=6.6., 3,425.3) have a high chance of presenting together. Time intervals included about a 90-day uncertainty regarding the amount of time participants had to develop HUD from first use. The sensitivity analysis rid intervals of this err in exchange for a less fine grain natural history assessment. The strongest PE to PE coalescence among participants with 0-150 days since first heroin use to assessment were trying to cut down at least once and being unable to cut down – PEs within the same DSM-5 HUD criteria. Being unable to set limits and withdrawal syndrome symptoms were strongly associated with each other (OR=416.7, 95% CI=35.8, 4,845.8) and qualify as a HUD diagnosis. Other strong associations were among spending a lot of time getting or using heroin and withdrawal symptoms (OR=127.4, 95% CI=18.1, 897.2) and having problems with emotions along with withdrawal symptoms (OR=107.9, 95% CI=10.2, 1,140.8). Both PE pairs qualify as a HUD diagnosis. Between 150-270 days after first using heroin results suggest characteristic PEs include spending a lot of time getting or using, signs of tolerance, and spending less time doing important activities. A robust association is seen between diagnosable HUD PEs spending a lot of time getting or using and needing more to get the same effect (OR=1,008.0, 95% CI=99.4, 87 10,219.5). Additionally, spending less time doing important activities and spending a lot of time getting/using or needing more to get the same effect also have an increased chance of presenting together (OR=258.3, 95% CI=41.3, 1,615.2; OR=369.7, 95% CI=50.0, 2,731.6, respectively). Sensitivity analyses roughly corresponding to this timeframe (i.e., 150-300 days) suggest problems with family or friends increases the risk of also having serious problems or trouble with the law (OR=663.0, 95% CI=147.5, 2,979.8; OR=242.0, 95% CI=25.9, 2,260.7, respectively). Spending a lot of time getting or using and spending less time doing important activities also appear to have a strong coalescence during this time. Within 300-420 days of first using heroin, HUD is evident from robust associations between spending less time doing important activities and use causing serious problems (OR=261.8, 95% CI=28.3, 2,425.0 ), having problems with emotions and spending less time doing important activities (OR=217.6, 95% CI=25.4, 1,864.5), and spending less time doing important activities and physical danger (OR=115.1, 95% CI=8.3, 1,597.0). Each of these combinations qualify as a DSM-5 HUD diagnosis because PE pairs include two distinct DSM criteria. Within 330-450 days of first using, HUD is again evident from large associations between spending a lot of time getting or using, having problems with emotion, spending less time doing important activities, unable to set limits, and continued use despite problems with family or friends. Sensitivity analysis confirm the time-frame of 300-450 days of first using heroin strongly correlates with spending a lot of time getting or using heroin, having problems with emotions, continued use despite problems with family or friends, physical danger, and spending less time doing important activities. The strongest coalescence is seen between spending a lot of time getting or using and continued use despite having problems with family or friends (OR=558.3, 88 95% CI=64.9, 4,803.9). Not only does this PE pair qualify as a HUD diagnosis, but it has been shown to be a prominent combination throughout lag-time intervals. Problems with family or friends is a prominent PE associated with the development of HUD. Shane Darke’s work within the National Drug and Alcohol Research Centre in Australia describes early-life parent/family discord such as parental drug use, separation/absence, psychopathology, and child abuse (50). Much of those with HUD as adults experienced childhood psychopathology, specifically antisocial behavioral disorders and 40-80% met diagnostic criteria for childhood conduct disorder (50). This connection between personal relationships and heroin use may point to: 1) a feedback loop between family relationships and psychiatric comorbidities with HUD 2) the degree to which heroin corresponds to neuroadaptation responsible for personal relationships, and/or 3) HUD intervention points during latency period(s). Entangled within a strong correlation between spending a lot of time getting or using heroin and continued use despite problems with family or friends is a likely feedback loop. Animal model research has suggested that drug seeking behavior can be precipitated by stressful stimuli (70). Equally, PE to PE associations between stressful stimuli, for example physical danger, trouble with the law, having serious problems, may drive NIHUs to spend more time getting/using heroin. Based on that premise, HUD could possibly develop in a manner interdependent with the consequences of the initial heroin use. Strengths and Limitations: The current study relies on annual cross-sectional surveys intended to yield nationally representative samples. There are three limitations intrinsic to this study design: 1) Left truncation and left censoring may underestimate the number of NIHU. To directly combat challenges of left truncation and censoring, the newly incident heroin use case definition (i.e., within 12 months of assessment) restricts the amount of time participants have to 89 develop HUD-related experiences that would keep them from being sampled or completing the interview (e.g., incarceration, fatal overdose). Even so, considering the ratio of newly incident heroin users to those who die of heroin overdose in the first year of use, potential left truncation is negligible. The same is true of left censoring when reflecting on those incarcerated within the first year of use. 2) The study’s reliance on self-report merits attention, yet there is currently no feasible alternative for surveys assessing history of drug use. 3) Cross-sectional surveys are often criticized for limited temporal sequencing. Notably, the current study circumvents this issue given participants cannot develop heroin use disorder without first having tried the drug. Likely explanations for the robust point estimates and wide confidence intervals may reflect: 1) There may be issues of sample size and small cell counts. Despite the rise in heroin use incidence, it is still a relatively rare phenomenon. Analytically, this poses challenges. Thinly slicing cross-sectional data to ascertain NIHUs within 12 months of assessment and further stratifications yield small sample sizes within each lag-time interval and involve zero cells when calculating PE to PE ORs. As a result, OR point estimates are notably large and the associated 95% confidence intervals are wide. 2) There may also be exchangeability between PE pairs. Exchangeability is seen when two cross tabulated binary variables that may be measuring the same underlying trait. PEs within the same DSM-5 HUD criteria (e.g., spending a lot of time getting or using/spending a lot of time getting over the effects) readily speak to the concept of exchangeability in that the two PEs are measuring the same behavior. Large ORs of PEs that are not in the same diagnostic criteria may reflect the two PEs picking up on the same construct, HUD. Via the logistic regression models, the strength of association linking each PE pair might be inverse or might be positive. The OR estimator has been used because it is not margin- 90 dependent. Other statistical indices of agreement and association such as kappa or correlation coefficients would depend upon the marginal frequencies of the PE. 4.5 Conclusions Among all drug use disorder, that of heroin has the highest burden of disease with mortality rates comparable to that of the elderly (50). That combined with the continued upward trend of opioid mortality in the US should be concerning to researchers, public health officials, healthcare teams, and all as citizens. Prevention and intervention efforts have already curbed prescription opioids by implementing stricter physician prescribing recommendations and pill return centers. In contrast, heroin use interventions are lagging behind in prevalence and efficacy. With this study suggesting heroin-associated emotions and interpersonal relationships as important manifestations of HUD development, intervention efforts might consider a focus on that arena. For instance, clean needle exchanges could make available group therapy between an individual user and their non-drug using support system. This could be modified for primary prevention by providing therapy for prescription pain relievers since they are more vulnerable to heroin use later. The group counseling would be between the individual receiving the medication and others living in their household and/or close family and friends. To promote adherence, therapy via telephone could be an option. Including individuals within the patient’s already established social network would call upon Valente’s work on social diffusion (71). That is, it may be beneficial to work on controlling the diffusion of opioid use to different social networks and help keep a strong support system within the existing network (71). In general, intervention efforts geared toward individuals who use heroin should purposefully include close friend and family of the user in order to work within a social network. This may include but is not limited to education efforts, naloxone training, surveillance, 91 rehabilitation, and physical activity-based interventions. Next steps for the field include adapting research to randomized control trials which would allow immediate intervention and inferences that may more readily speak to causal interpretations. 92 CHAPTER 5 MANUSCRIPT 2 – EVALUATING MEASUREMENT EQUIVALENCE OF HEROIN USE DISORDER ACROSS HISTORY OF EXTRA-MEDICAL PRESCRIPTION OPIOID USE AND SEX 5.0 Abstract Aim: The current study aims to assess measurement equivalence of NSDUH audio computer assisted self-interview module as a measure of heroin use disorder (HUD), assuming a single dimension to evaluate against sex and extra-medical prescription opioid use history. Methods: National Surveys on Drug Use and Health (NSDUH) 2002-2016 aggregated files include 837,326 participants with 896 newly incident heroin users (NIHUs) identified. Problems and experiences (PE) of HUD were recoded into 10 diagnostic criteria dichotomous indicators. A single factor model was assumed for HUD. Chi-square tests for model differences compared nested models to assess metric and scalar equivalence across sex and extra-medical prescription opioid use history (EMPOU). Results: Assessing HUD across sex, models constraining loadings and thresholds fail to reject the null hypotheses of equal model fit. Constrained loadings vs free model: c2 = 10.907 (p>0.05); constrained loadings and threshold compared to free model: c2=26.730 (p>0.05). Assessing HUD across EMPOU, models constraining reject the null hypotheses of equal model fit (c2 = 10.271, p<0.001). Discussion: With respect to HUD measurement equivalence, the estimates indicate loadings and thresholds are not appreciably different when males-female contrasts are made; the null hypothesis (equivalent values) cannot be rejected. Conversely, measurement equivalence was not confirmed for HUD across EMPOU subgroups. Conclusions: The study supports continued study of male-female variations in HUD levels without calibration of measurements, but the study of HUD levels across EMPOU subgroups 93 will require more research with calibration of the current tools used to measure HUD as a dimensional construct. 94 5.1 Introduction HUD can be studied via algorithmic combinations of 20 problems and experiences (PE) items designed to measure 10 criteria designated by the Diagnostic and Statistical Manual 52 (Table 41, 42)3. Alternately, HUD can be studied as a dimensional latent construct for which NSDUH provides no tangible ‘gold-standard’ diagnosis. Since HUD, as a latent construct, is not directly observable in these data, there is uncertainty about the appropriate parameters of the dimensional measurement model. More specifically, when one combines PE experiences for comparison of HUD levels across subgroups of newly incident heroin users (e.g., females versus males; prior opioid users versus never users), is there validity of the comparisons when an uncalibrated HUD measurement is used? Research has yet to answer this question as it relates to HUD levels and potential sex-differences or exposure to extra-medical prescription opioid use. Measurement Equivalence: Measurement equivalence (or invariance) involves elaborated structural equation modeling used to compare variation or differences of latent constructs between different groups or time points (72). In simpler terms, it is a statistical property meant to demonstrate that the construct of study can be measured without calibration challenges across subgroups or across time (73). While latent constructs are by definition not directly observable (e.g., depression or HUD level) there are observable indicators of the construct that are measurable (e.g., sad or depressed mood; heroin withdrawal). A confirmatory factor analysis (CFA) can be used for testing the construct validity in which there is already an 2 The National Surveys on Drug Use and Health, 2002-2016, base survey questionnaire on DSM-IV criteria which is different from DSM-5 in that it includes the problem/experience of having trouble with the law. DSM-IV does not include the problem/experience of craving which is included in DSM-5. 3 Symptoms listed when asking about withdrawal experience: 1) feeling kind of blue or down, 2) vomiting or feeling nauseous, 3) having cramps or muscle aches, 4) having teary eyes or a runny nose, 5) feeling sweaty, having enlarged pupils, or having body hair standing up on your skin, 6) having diarrhea, 7) yawning, 8) having a fever, and 9) having trouble sleeping. 95 established conceptual and measurement framework (73). Using CFA, evaluation of three forms of measurement equivalence can be achieved: configural, metric, and scalar (Table 43). The current study evaluates the continuous latent construct HUD based on ordered categorical indicators across multiple groups. Such conditions require unique identification conditions in order to estimate the model parameters (74)(75). Namely, the scale (i.e., mean and variance) of ordered categorical indicators is unknown, which requires additional model constraints (74). There are various recommendations on ways to constrain said model. Resulting parameter estimates may vary, but the standardized parameter estimates and fit indices will not be affected (74). There are two parameterizations that can be used for multiple group analysis - the delta approach and the theta approach (76). This study will use the theta approach in which the residual variances are standardized to equal one in the overall group and are free for subgroups (76). For this reason, the stepwise constraints to assess levels of measurement equivalence will not include constraints on residual variances. Additional identification conditions, suggested by Millsap and Tien (2004), that are used in this study are outlined within the methods section. Sex Differences: Both males and females have experienced an increase in heroin use, with aggregate data suggesting males age 25-44 to be the largest using demographic subgroup (6). Likewise, past epidemiologic research has shown that drug use is a phenomenon predominantly among males (22)(36)(37), yet as of late, studies have suggested otherwise for several drugs (e.g., alcohol) (38)(39)(40). Male and female prevalence of heroin use once suggested a large disparity, has narrowed respectively from 2.4 and 0.8 persons/1,000 in 2002- 2004 to 3.6 and 1.6 persons/1,000 in 2011-2013 (41). In simpler words, over time sex differences in the prevalence of heroin use have diminished over time. 96 There may be biological differences between males and females that influence sex- specific reactions to drugs. Ovarian hormones or metabolites may influence females’ experience with drugs as studies have shown that the subjective high felt can fluctuate with the female menstrual cycle (77). Along the same lines, some studies indicate for females a lessened stress response after drug use. These differences seem to be unique to female drug use and in theory could possibly influence susceptibility to HUD. There is evidence that females more rapidly progress to a use disorder after drug use onset and have experienced more severe job-related impairment related to opioid use disorder (77), but measurement equivalence issues have not been resolved. Thus, before making male-female comparison of HUD levels, there is reason to investigate sex differences that might create measurement problems when measuring HUD levels or in the progress on HUD development. Extra-Medical Prescription Opioid Use: It is well established that there is an association between extra-medical prescription opioid use and later progress to heroin use (78)(79). Pharmacologically, heroin and prescription opioids are very similar in their interactions with the endogenous opioid system in the body. Both involve mu-opioid receptor signaling and influence dopamine availability in brain regions such as the nucleus accumbens (78). However there are differences across heroin and prescription opioids can be seen in various parameters: lipophilicity, mu-receptor binding affinities, and pharmacokinetic properties (78). This leaves uncertainty as to whether having used prescription opioids extra-medically in the past may differentially influence measurement of HUD as a latent dimensional construct. It may be that EMPOU history is associated with a more rapid progression across HUD levels after initiation, but measurement calibration might be required before measurement equivalence is achieved. Overview: Research has yet to evaluate whether HUD level as a latent construct is comparable between males and females. Based on the fact that females tend to start heroin use 97 younger than males, it may be that likewise females outpace males in HUD development (38). Additionally, HUD diagnoses do not account for previous exposure to opioids, which may in fact prime individuals in terms of the various indicators used to measure HUD (e.g., spending a lot of time getting or using; tolerance). The current study aims to assess measurement equivalence of heroin use disorder, assuming a single dimension to evaluate against sex and extra-medical prescription opioid use history. A priori hypotheses about new heroin users were: (1) Males and females are not comparable in HUD measurement; (2) Subgroups defined by extra-medical use of prescription opioids, past year, lifetime, and never users are not comparable in HUD measurement. 98 by your use of heroin? work, or school? have put you in physical danger? “During the past 12 months…” Problems & Experiences using heroin? wanted? were probably caused or made worse by your use of heroin? important activities (spending time with friends & family)? have problems with your emotions, nerves, or mental health? Table 41. Problems and Experiences of Heroin Use Based on Diagnostic Criteria. Data from United States National Surveys on Drug Use and Health, 2002-2016. PE # 1 Did you try to set limits on how often or how much heroin you used? 2 Did you have any problems with your emotions, nerves, or mental health that 3 Was there a month or more when you spent a lot of your time getting or 4 Did you need to use more heroin than you used in order to get the effect you 5 Did you have any problems with family or friends that were probably caused 6 Did using heroin cause you to give up or spend less time doing these types of 7 Did using heroin cause you to have serious problems like this either at home, 8 Did you cut down or stop using heroin at least one time? 9 Did you continue to use heroin even though you thought it was causing you to 10 Did you regularly use heroin and then do something where using heroin might 11 Did you continue to use heroin even though you thought it caused problems 12 Were you able to keep to the limits you set, or did you often use heroin more 13 Were you able to cut down or stop using heroin every time you wanted to or 14 Did you have 3 or more of these symptoms after you cut back or stopped 15 Did you have 3 or more of these symptoms at the same time that lasted for 16 Did using heroin cause you to do things that repeatedly got you in trouble with 17 Did you notice that using the same amount of heroin has less effect on you 18 Was there a month or more when you spent a lot of your time getting over the 19 Did you have any physical problems that were probably caused or made 20 Did you continue to use heroin even though you thought it was causing you to NA Craving NSDUH Downloadable Public Use Dataset. longer than a day after you cut back or stopped using heroin? the law? that it used to? with family or friends? than you intended to? effects of the heroin you used? worse by using heroin? have physical problems? tried to? using heroin? DSM IV 5 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 99 Inability to manage commitments due to use Table 42. DSM-5 Use Disorder Criteria and Corresponding Heroin Use Disorder Problems and Experiences. Data from United States National Surveys on Drug Use and Health, 2002-2016. # Criterion 1 Using in larger amounts or for longer than intended 2 Wanting to cut down or stop using, but not managing to 3 Spending a lot of time to get, use, or recover from use -- Craving 4 5 Continuing to use, even when it causes problems in relationships 6 Giving up important activities because of use 7 Continuing to use, even when it puts you in danger 8 Continuing to use, even when physical or psychological problems 9 10 Withdrawal symptoms NSDUH Public Use Dataset. Source: American Psychiatric Association, 2013 (19). PE16 (problems with the law) not included in DSM-5 criteria. Craving not included in NSDUH survey assessment. Corresponding PE 1, 12 8, 13 3, 18 N/A 7 5, 11 6 10 2, 9, 19, 20 4, 17 14, 15 may be made worse by use Increasing tolerance Table 43. Description of Confirmatory Factor Analysis Measurement Equivalence Levels Description Configural Null model. Metric Scalar Factor loading, thresholds (i.e., intercepts), and residual variances are free. Factor loadings constrained. Factor loadings and thresholds constrained. Fit Indices Overall fit Chi-Square Chi-Square RMSEA CFI/TLI Good Fit Standards The smaller the better. The smaller the better. Unacceptable >0.10 Good <0.06 Acceptable >0.90 Good >0.95 Table based on Claremont Evaluation Center. (73) Link available: http://comm.eval.org/HigherLogic/System/DownloadDocumentFile.ashx?DocumentFileKey= 63758fed-a490-43f2-8862-2de0217a08b8 100 Figure 10. Diagram of Confirmatory Factor Analysis Model Testing Measurement Equivalence of Problems and Experiences of Heroin Use Disorder Among Newly Incident Heroin Users. Heroin Use ll Disorder l1 l2 l20 l19 PE19 PE20 e19 e20 Latent variable: heroin use disorder. Indicators: Problems and Experiences (PE) numbers 1 through 20. Residual error: e Factor loadings: l CFA diagram with for DSM-5 criteria replacing problems and experiences (PE) indicators. PE1 PE2 e1 e2 5.2 Methods Sample: The study’s population for the US National Surveys on Drug Use and Health (NSDUH), 2006-16, consists of non-institutionalized US civilians in all 50 states and D.C., restricted to those 12 to 21 years of age. Multi-stage area probability sampling and institutional review board approved protocols for recruitment and standardized computer-assisted self- interviews were used. As a result, aggregate files included 837,326 participants, with 896 identified as newly incident heroin users (NIHUs) from survey years 2002-2016. NIHUs were assessed within 12 months after first use, with all past users excluded (Figure 11). The US Department of Health and Human Services Center for Behavioral Health Statistics and Quality created NSDUH open access analysis files with de-identified data after applying disclosure analyses designed to prevent re-identification of participants. Given the circumstances 101 of open access and no contact with participants, the Michigan State University institutional review board ruled that plans to analyze these data qualified for the federal category “not human subjects research.” Measurements: Observable indicators of HUD levels included 20 questions on problems and experiences (PE) based on the Diagnostic and Statistical Manual IV criterion for case ascertainment (Table 45). PE indicators were coded as binary response variables. NSDUH survey questions use ‘gating’ (e.g., based on NSDUH measurement assumptions or on logic); hence, not all 896 NIHUs are asked all 20 questions. To have PE-specific proportions with the same denominator, 896, a skipped item is coded 0 and reflects the measurement assumption). All PE variables were recoded into 10 binary indicators based on DSM-5 HUD case ascertainment criteria (Table 46). Among 20 PEs, a DSM-IV ‘legal troubles’ PE was dropped to match DSM-5 HUD criteria. (Note: NSDUH 2002-2016 did not assess DSM-5-specified ‘craving.’) Subgrouping of new heroin users involved sex (i.e., male, female) and extra-medical prescription opioid use history (EMPOU). Subgroups were: 1) EMPO use <=12 months of assessment, 2) lifetime EMPOU history >12 months before assessment, and 3) never-EMPOU. Statistical Analyses: PE and criteria binary variables were recoded using Stata SE 12. Corresponding PE and criteria-specific proportions (‘attack rates’) were estimated with numerators based on new heroin users ‘positive’ for the corresponding PE/criterion. Measurement equivalence was assessed via MPlus version 7.3 software. HUD levels were measured with the 10 criterion indicator variables that combined 20 PE item responses. A single-factor model in which each observed indicator loads on only one factor is identified as a congeneric factor structure. In this case, binary indicators imply that only one threshold parameter is needed for each observed indicator. This congeneric model with 102 dichotomous indicators requires an alternative set of constraints relative to polytomous indicators (75): 1. All thresholds are free to vary, except for a subset that are constrained to be invariant across subgroups. 2. Common factor matrices vary freely. Common factor means in the overall group are fixed at zero, but subgroup means freely vary. 3. All unique factor matrices are fixed overall; within subgroups, they vary freely. 4. The thresholds are fixed to be equal for each subgroup. 5. For all subgroups besides overall group, diagonal elements of sum unit values are fixed. This congeneric model does not allow residual variances to be estimated. Three models were estimated, two of which were nested within the baseline model for comparison. Model 1 allowed both thresholds and factor loadings for all subgroups to be freely estimated. Model 2 constrained factor loadings with chi-square used to test model differences between Model 1. Model 3 constrained thresholds and factor loadings with chi-square used to test model differences between Model 1. Configural equivalence was assumed to allow all indicators to load onto one ‘Level of HUD’ factor. Metric equivalence was assessed in Model 2. Scalar equivalence was assessed in Model 3. Goodness of fit statistics such as RMSEA, CFI, and TLI were also used. RMSEA values less than 0.05 are generally considered to be of good fit (73). CFI and TLI values greater than 0.95 are generally regarded as indicative of good model fit (73). Initial unweighted analyses were repeated with analysis weights using Taylor Series Linearization for calculus-based variance estimation. MPlus specifications included complex analysis type and weight, stratification, and cluster commands. 103 The dichotomous congeneric model does not allow residual variances to be estimated. Three models were estimated, two of which were nested within the baseline model for comparison. Model 1 allowed both thresholds and factor loadings for all subgroups to be freely estimated. Model 2 constrained factor loadings with chi-square used to test model differences between Model 1. Model 3 constrained thresholds and factor loadings with chi-square used to test model differences between Model 1. Configural equivalence was assumed to allow all indicators to load onto one factor for HUD assessment. Metric equivalence was assessed in Model 2. Scalar equivalence was assessed in Model 3. Goodness of fit statistics such as RMSEA, CFI, and TLI were also used. RMSEA values less than 0.06 are considered to be of good fit (73). CFI and TLI values greater than 0.95 are considered to be of good model fit (73). Initial unweighted analyses were repeated with analysis weights using Taylor Series Linearization for calculus-based variance estimation. MPlus specifications included complex analysis type and weight, stratification, and cluster commands. 104 2003 2004 2005 2006 2007 2008 2009 n=54,079 n=55,230 n=55,602 n=55,905 n=55,279 n=55,435 n=55,110 n=55,234 2012 n=55,268 2013 n=55,160 2014 n=55,271 2015 n=57,146 2016 n=56,897 2002 2010 2011 n= 57,313 n= 58,397 Figure 11. Flow of Participants in Newly Incident Heroin Use Case Ascertainment. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH – Year-Specific Files NSDUH n= 837,326 2002-2016 Aggregate Files NSDUH Downloadable Public Use Dataset. Unweighted counts (n). Newly incident heroin use defined as first heroin use within 12 months of survey assessment; past onset users excluded. Newly Incident Heroin Users Never Used Heroin Past Onset Heroin n=825,420 n=9,153 n=896 105 Table 44. Characteristics of Newly Incident Heroin Use Sample. Data from United States National Surveys on Drug Use and Health, 2002-2016. Aggregated NSDUH 2002-2016 n=837,326 n (%) Newly Incident Heroin Users n=896 n (%) Demographic Characteristics Sex Age Groups (Years) Male 12-17 18-25 26-34 35-49 50-64 65+ 401,270 (48) 258,309 (10) 263,258 (13) 93,449 (14) 128,684 (25) 56,998 (22) 36,628 (16) 532,503 (67) 106,106 (12) 12,284 (<1) 4,042 (<1) 30,449 (5) 26,309 (1) 134,633 (14) 476 (62) 227 (15) 539 (47) 82 (22) 44 (14) 4 (2) 0 715 (81) 21 (4) 20 (<1) 8 (1) 5 (1) 31 (1) 96 (10) Ethnic Self-Identification White Black/African American Native American/Alaskan Native Hawaiian /Other Pacific Island. Asian >1 Ethnicity Hispanic Extra-Medical Prescription Opioid History Lifetime Use (>12 Months*) Within 12 Months* Never Used Missing Data 89,390 (11) 88, 649 (9) 608,112 (74) 51,175 (5) 93 (10) 677 (76) 112 (13) 15 (2) NSDUH Downloadable Public Use Data. NIHUs: Newly incident heroin users first used heroin within 12 months of survey assessment. Past onset users excluded. Ethnic self-identification: all ethnicities other than Hispanic are specified as non-Hispanic per survey assessment. *More than or within 12 months of survey assessment. Unweighted n; weighted % 106 249 896 242 896 232 896 216 896 197 896 193 189 173 896 896 896 164 896 150 896 136 896 108 896 79 70 68 41 40 27 896 896 896 896 896 896 home, work, or school? caused by your use of heroin? using heroin? you wanted? 40.7 Did you try to set limits on how often or how much heroin you used? 31.4 Did you have any problems with your emotions, nerves, or mental health that were probably caused or made worse by your use of heroin? 27.6 Was there a month or more when you spent a lot of your time getting or 27.9 Did you need to use more heroin than you used in order to get the effect 25.6 Did you have any problems with family or friends that were probably 24.4 Did using heroin cause you to give up or spend less time doing these types of important activities (spending time with friends & family)? 22.5 Did using heroin cause you to have serious problems like this either at 22.7 Did you cut down or stop using heroin at least one time? 23.3 Did you continue to use heroin even though you thought it was causing you to have problems with your emotions, nerves, or mental health? 20.8 Did you regularly use heroin and then do something where using heroin 17.8 Did you continue to use heroin even though you thought it caused 17.3 Were you able to keep to the limits you set, or did you often use heroin 12.4 Were you able to cut down or stop using heroin every time you wanted 9.7 Did you have 3 or more of these symptoms after you cut back or 9.0 Did you have 3 or more of these symptoms at the same time that lasted 8.2 Did using heroin cause you to do things that repeatedly got you in trouble 5.7 Did you notice that using the same amount of heroin has less effect on 6.9 Was there a month or more when you spent a lot of your time getting 3.2 Did you have any physical problems that were probably caused or made 1.5 Did you continue to use heroin even though you thought it was causing for longer than a day after you cut back or stopped using heroin?* might have put you in physical danger? over the effects of the heroin you used? problems with family or friends? with the law? you that it used to? to or tried to? stopped using heroin?* more than you intended to? Table 45. Description of Problems and Experiences involving Heroin Use Disorder. Data from United States National Surveys on Drug Use and Health, 2002-2016. “During the past 12 months… “ Problems & Experiences Counts Wt. n. d. % 896 361 worse by using heroin? 896 13 NSDUH Downloadable Public Use Dataset. Unweighted n: numerator & d: denominator; % weighted percentages. you to have physical problems? 107 Table 46. Description of DSM-5 Criteria for Heroin Use Disorder. Data from United States National Surveys on Drug Use and Health, 2002-2016. Counts Wt. n. 361 896 40.7 Using in larger amounts or for longer than intended. 209 896 24.8 Wanting to cut down or stop using, but not managing to. 282 896 34.5 Spending a lot of time to get, use, or recover from use. d. % DSM-5 Criteria -- -- -- Craving. PE #s 1, 12 8, 13 3, 18 N/A 7 5, 11 6 10 2, 9, 19, 20 4, 17 14, 15 193 896 22.5 Inability to manage commitments due to use. 216 896 25.6 Continuing to use, even when it causes problems in relationships. 197 896 24.4 Giving up important activities because of use. 164 896 20.8 Continuing to use, even when it puts you in danger. Continuing to use, even when physical or psychological problems may be made worse by use. 276 896 34.6 273 896 33.6 Increasing tolerance. 130 896 16.0 Withdrawal symptoms. NSDUH Public Use Dataset. DSM-5 Criterion Source: American Psychiatric Association, 2013 (19). PE16 (problems with the law) not included in DSM-5 criteria. Craving is in DSM-5, but is not included in NSDUH survey assessment of heroin use disorder. Counts: unweighted n(numerator) and d(denominator); % weighted percentages rounded to thousandths place. 108 Table 47. Goodness of Fit Indices Evaluating Measurement Equivalence of Heroin Use Disorder Level Across Sex Among Newly Incident Heroin Users (Without Analysis Weights). Data from United States National Surveys on Drug Use and Health, 2002-2016. df df 70 80 c2 -- 10.907 298.293 181.790 p-value <0.001 <0.001 Chi-Square Model Fit c2 Chi-Square for Difference Testing p-value -- 0.3648 Models M1 – free model M2 – constrain loadings M1 vs M2 M3 – constrain botha M1 vs M3 NSDUH Downloadable Public Use Dataset. Sex: male/female. RMSEA: root mean square error of approximation Unweighted estimates. --Null model M1 is the full model used to test differences compared M2-M3 constrained models. aloadings and thresholds constrained. -- 10 20 <0.001 26.730 198.667 0.1430 90 Comparative CFI TLI 0.982 0.993 0.986 0.994 Absolute RMSEA 0.085 0.053 0.993 0.993 0.052 109 Table 48. Goodness of Fit Indices Evaluating Measurement Equivalence of Heroin Use Disorder Level Across Sex Among Newly Incident Heroin Users with Analysis Weights. Data from United States National Surveys on Drug Use and Health, 2002-2016. df df 70 80 c2 -- 15.850 139.526 137.391 p-value <0.001 <0.001 Chi-Square Model Fit c2 Chi-Square for Difference Testing p-value -- 0.1040 Models M1 – free model M2 – constrain loadings M1 vs M2 M3 – constrain botha M1 vs M3 NSDUH Downloadable Public Use Dataset. Sex: male/female. RMSEA: root mean square error of approximation Analysis weights applied. --Null model M1 is the full model used to test differences compared M2-M3 constrained models. aloadings and thresholds constrained. -- 10 20 <0.001 25.501 142.734 0.1829 90 Comparative CFI TLI 0.991 0.993 0.993 0.994 Absolute RMSEA 0.047 0.040 0.995 0.995 0.036 110 Table 49. Goodness of Fit Indices Evaluating Measurement Equivalence of DSM-5 Criteria for Heroin Use Disorder Level Across History of Extra-Medical Prescription Opioid Use Among Newly Incident Heroin Users (Without Analysis Weights). Data from United States National Surveys on Drug Use and Health, 2002-2016. Comparative CFI TLI 0.987 0.990 Absolute RMSEA 0.075 0.991 0.989 0.990 0.990 0.064 0.067 c2 df -- df 105 p-value <0.001 Chi-Square Model Fit c2 Chi-Square for Difference Testing p-value -- Models M1 – free model M2 – constrain loadings M1 vs M2 M3 – constrain botha M1 vs M3 NSDUH Downloadable Public Use Dataset. Sex: male/female. RMSEA: root mean square error of approximation Unweighted estimates. --Null model M1 is the full model used to test differences compared M2-M3 constrained models. aloadings and thresholds constrained. 108.807 125 145 -- 20 40 <0.001 <0.001 <0.001 <0.001 52.271 280.090 275.839 335.108 111 Table 50. Goodness of Fit Indices Evaluating Measurement Equivalence of DSM-5 Criteria for Heroin Use Disorder Level Across History of Extra-Medical Prescription Opioid Use Among Newly Incident Heroin Users with Analysis Weights. Data from United States National Surveys on Drug Use and Health, 2002-2016. df 165.564 216.660 246.127 c2 -- 55.020 df 105 125 145 p-value 0.002 <0.001 Chi-Square Model Fit c2 Chi-Square for Difference Testing p-value -- <0.001 Models M1 – free model M2 – constrain loadings M1 vs M2 M3 – constrain botha M1 vs M3 NSDUH Downloadable Public Use Dataset. Sex: male/female. RMSEA: root mean square error of approximation Analysis weights applied. --Null model M1 is the full model used to test differences compared M2-M3 constrained models. aloadings and thresholds constrained. -- 20 40 <0.001 <0.001 92.529 Comparative CFI TLI 0.990 0.987 0.992 0.988 Absolute RMSEA 0.044 0.050 0.987 0.988 0.049 112 5.3 Results Testing measurement equivalence across sex and EMPOU using 20 PE items as indicators, rather than 10 criterion indicator variables, showed that some items were highly correlated with one another and should be combined for better estimation. Results on the 20 items do not include PE measurement equivalence assessment due to this poor model estimation. Ten criteria were specified as observed indicator variables for the ME modeling steps. Sex: Model 1 comparative fit indices generate CFI=0.986 and TLI=0.982. Model 1 absolute index RMSEA=0.085. Model 1 with loadings and thresholds free to vary compared to Model 2 with constrained factor loadings yields c2 = 10.907 (p>0.05) (Table 47). Chi-square test for difference testing fails to reject the null hypothesis, suggesting no need for measurement calibration. Comparative indices indicate good model fit (CFI=0.994, TLI=0.993). Absolute index suggests near-adequate fit (RMSEA=0.053). Model 1 compared to Model 3 with constrained loadings and thresholds fails to reject the null hypothesis, suggesting no calibration need (c2=26.730 (p>0.05). Model 3 comparative indices show good model fit (CFI=0.993, TLI=0.993). Absolute index for Model 3 suggests near-adequate fit (RMSEA=0.052). Model comparisons with analysis weights show Model 1 versus Model 2 yields c2=15.870 (p>0.05) and Model 1 versus Model 3 yields c2=25.501 (p>0.05) (Table 48). Both chi-square tests for differences fail to reject the null hypothesis, suggesting no need for measurement calibration Extra-Medical Prescription Opioid Use: Model 1 comparative fit indices generate CFI=0.990 and TLI=0.987. Absolute fit index RMSEA= 0.075. Model 1 with loadings and thresholds free to vary compared to Model 2 with constrained factor loadings yields c2 = 10.52.271 (p<0.001) (Table 49). Null hypothesis of equal fit between Model 1 and Model 2 is rejected, indicative of need for measurement calibration. Comparative model fit indices for Model 2 suggest good model fit (CFI=0.991, TLI=0.990). Absolute fit index suggests near- 113 adequate fit (RMSEA=0.064). Model 1 compared to Model 3 with constrained loadings and thresholds yields c2=108.807, (p<0.001). Comparative fit indices generate CFI=0.989 TLI=0.990 and absolute fit index generate RMSEA=0.067 suggesting acceptable model fit. Model comparisons with analysis weights show Model 1 compared to Model 2 yields c2=55.020 (p<0.001) and Model 1 compared to Model 2 yields c2=92.529 (p<0.001) (Table 50). Both chi- square tests for differences reject the null hypothesis of equal fit; measurement calibration is needed. 5.4 Discussion Among newly incident heroin users, assessing measurement equivalence of HUD across sex yields results that lend support to inferences about both metric and scalar equivalence. The completely free model (M1) and the constrained loadings model (M2) are not significantly different and the more parsimonious model is not rejected. Without calibration, NSDUH items can be used to study sex differences in HUD levels among newly incident heroin users. The addition of analysis weights yields the same conclusion of metric equivalence. The implication is that male-female HUD levels can be compared without additional measurement calibration steps. Likewise, the free model (M1) and the constrained loadings and threshold model (M3) are not significantly different, meaning the more parsimonious model is not rejected. This is evidence that no measurement calibration is needed. The addition of analysis weights yields the same conclusion of scalar equivalence. Thus, HUD levels of males and females could be compared based on their responses captured by these criterion indicator variables. Among newly incident heroin users, there is not measurement equivalence of HUD across extra-medical prescription opioid use history subgroups. Measurement calibration work will be needed if this comparison is to be made validly. 114 Models with constrained loadings yield better model fit than the completely free model, meaning the parsimonious model of measurement equivalence must be rejected. Similarly, constraining both loadings and thresholds produces better model fit than the completely free model. Therefore, EMPOU history designates NIHU subgroups for whom the meaning of HUD items might differ, or for whom the items perform differently as measurements of HUD levels. Further research and measurement calibration will be needed if we are to make valid comparisons of EMPOU subgroups in relation to HUD levels among newly incident heroin users. (One potential intermediate approach would be a measurement equivalence assessment with EMPOU dichotomized to ever and never users.) Strengths and Limitations: The current study relies on annual cross-sectional surveys intended to yield nationally representative samples. There are three limitations intrinsic to this study design: 1) Processes akin to left truncation and left censoring in follow-up studies may lead to under-enumeration of some NIHU in the study population. To directly combat challenges of this type, the newly incident heroin use definition might be shortened in order to restrict the amount of time participants have to develop HUD-related experiences that would keep them from being included in the sample or from completing the interview (e.g., incarceration, fatal overdose). Even so, considering the ratio of newly incident heroin users to those who die of heroin overdose in the first year of use, left -truncation-like processes might be negligible. The same is true of left censoring when reflecting on those sampled but incarcerated or overdosing before assessments are complete. 2) The study’s reliance on self-report merits attention, yet there is currently no feasible alternative for nation-level surveys assessing history of drug use. 3) Cross-sectional surveys are often criticized for limited temporal sequencing issues. Notably, the current study circumvents this issue given participants cannot develop heroin use disorder without first having tried heroin. 115 Additionally, to evaluate measurement equivalence the chi-square test of differences between models was used. The reliance on this test has limitations. When evaluating measurement equivalence between three groups for EMPOU history, rejecting the null hypothesis suggests there are subgroup differences and that there is not measurement equivalence. Yet, it is still unknown where the source of the differences might be found. It is unknown if all three groups are not comparable to each other or if there are two groups that might be collapsed. Counter-balancing strengths include a sample of newly incident heroin users identified within samples and under standardized survey conditions that are designed to produce nationally representative samples with controlled selection probabilities and with proper attention to analysis weights that reflect those selection probabilities. The DSM-IV criteria are assessed, often with multiple items that have been combined here in order to strengthen the assessment of DSM-5 HUD diagnostic criteria. Notwithstanding the omission of DSM-5 ‘craving’ items, the resulting covariation of criterion indicator variables suggests coherence of the measurement of HUD levels in these newly incident users. A clear basis for making comparisons between males and females can be seen. More measurement calibration work is needed before it is possible to compare HUD levels across subgroups defined by histories of extra-medical use of prescription opioid pain relieving compounds. 5.5 Conclusions This study’s focus is on the measurement models used to evaluate HUD levels among newly incident heroin users. This methods contribution creates a more solid basis for comparing males and females in relation to their HUD levels as observed soon after heroin onset. Some additional measurement calibration work might be done to address the vexing issue of residual variances, but solutions might not less achievable when the PE and criterion response indicators 116 are binary (0/1) as compared with measurement models for indicators with Gaussian or normalized response distributions. The same cannot be said for comparisons of NIHUs across subgroups defined by prior histories of opioid pain relievers. Additional measurement modeling will be required, and calibration of the HUD level measurement seems indicated at this point in the investigation. In measurement model work of this type, one potential source of non-equivalence involves how the respondents interpret the meaning of assessment items, and whether there are variations in interpretation or understanding about what was expected by those who designed the measurements. In measurement models for levels of drug use disorders, the source of variation might be traced to subgroup variations in pharmacokinetics (biotransformation, metabolism rates), involving issues much different from the just-mentioned ‘variation in meaning’ issues. For example, the EMPOU with recent opioids use might already be opioids-tolerant such that tolerance to heroin become manifest quickly rather than slowly. From a measurement modeling perspective, the PE ‘tolerance’ items might be ‘easier’ (with a lower threshold) and possibly less discriminating (with a shallower ‘loading slope’) across EMPOU subgroups. Origins of measurement non-equivalence also can be found when experiences and context vary. Social sharing of heroin and social isolation of heroin users might differ across sex or EMPOU subgroups (80). If so, if female new heroin users experience more sharing of heroin or more social connectedness within heroin-using groups, they might not experience having to spend a lot of time getting heroin, as compared with male counterparts, or vice versa. There are implications for clinical practice of note. First, the methodological results highlight that measurement tools for diagnostic workup are often assumed to function equivalently across populations. However, this may not be the case. During a consultation with young patient who says heroin use just started, the non-specialist clinician or counselor might not 117 immediately think about whether prior histories of opioids or other drug use might be important to evaluate during the course of asking questions about heroin experiences and trying to decide whether referral to a specialist is needed. Second, diagnostic criteria for heroin use disorder have shifted downward (i.e., with ‘mild’ implying just two criteria have been fulfilled). The result might be greater sensitivity of the assessment – i.e., to identify more mild cases of HUD with the presence of only two diagnostic criteria. In public health work one can give consideration to improvement of HUD assessment to better identify cases for early referral for evaluation and treatment by specialists. Thus, this methods investigation might have some potential importance in efforts to control HUD and attenuate heroin-related overdose mortality. 118 CHAPTER 6 MANUSCRIPT 3 – WILL THE OPIOIDS CRISIS PRECIPITATE EXCESS RISK OF A STIMULANT CRISIS? 6.0 Abstract Aim: This study aims to investigate the degree to which onset of heroin use may precipitate excess risk of onset of stimulant use. Methods: The study population consisted of non-institutionalized civilian residents of 50 states and DC, sampled for the US National Surveys on Drug Use and Health (NSDUH), 2002-2016 (n=837,326 participants). Among them, newly incident extra-medical stimulant users (NISUs) were identified (including prescription stimulants (e.g., amphetamines) or cocaine). A case crossover design was used to study newly incident heroin use (NIHU) prior to NISU with 2- month hazard and control intervals specified a priori. Analysis weights and Taylor Series Linearization are used (e.g., for calculus-based variance estimation). Results: Discordant pair case crossover odds ratios show no association (OR=1.0, 95% CI=0.8, 1.2) both with and without analysis weights. Post hoc exploration shows a moderate association between NIHU and NISU with 1-month hazard and control intervals (OR=1.3, 95% CI=1.0, 1.7). Discussion: Two months after NIHU does not appear to be a time of excess risk for NISU. The post hoc specification for one-month hazard and control intervals identify event minus 1 as a month of excess risk of starting to use stimulants extra-medically. Possible explanations for these findings might be methods-related (e.g., correlated recall error) or substantively important (e.g., environments conducive to new opportunities to try drugs). Conclusions: Whereas the ‘a priori’ specification indicates a null relationship, the ‘post hoc’ 1- month specification can be used to guide future investigations of this type. Closely following drug onset an individual may have relatively more opportunities to try other drugs given their environment during that interval. In this way, heroin onset might be quickly followed by 119 psychostimulant onset. Possible prevention methods may include virtual reality simulations or roleplaying to prepare individuals for situations that can occur as a result of initial drug use. 120 6.1 Introduction Trends in drug use have shown some cycles of note. The US experience with the heroin use epidemic of the late 1960s and early 1970s was followed by an epidemic cocaine and other psychostimulant use (e.g., methamphetamine ‘ice’) during the next two decades. Likewise, epidemiologic evidence suggests stimulant use now is returning toward epidemic proportions as the current US opioids crisis ebbs. Linkages between opioids and psychostimulants suggest interesting patterns of co- occurrence or sequencing. For example, opioids include prescription pain relievers, heroin, and synthetic opioids, all of which can induce drowsiness (among other ‘downers’ in the pharmacopeia). On this basis, the concept of opioids as ‘narcotics’) originates from Greek narcoun, meaning to benumb, make unconscious (80). In contrast, stimulants including amphetamine, methamphetamine, cocaine, and crack cocaine promote wakefulness (among other ‘uppers’ in the pharmacopeia) (11). Some prescription stimulants are even used to directly combat sleep for disorders such as narcolepsy (11). Given the difference in subjective effects of opioids and stimulants, the intuitive notion may be that those who tend to use these different drugs represent distinct subgroups. Yet, one could speculate that the widespread use of opioids may lead individuals to seek remedies for their opioid-induced drowsiness and fatigue. Thus, it is plausible that opioid and stimulant users may be overlapping subgroups, at the very least. Evidence of an overlap has been shown in reports about the ‘speedball’ combination (e.g., heroin and cocaine), as well as in research on overdose deaths where both cocaine and some form of opioid have been detected (81). Several unanswered epidemiological questions about the ‘downers-uppers’ relationship prompt the current investigation about predicting stimulant use as might be triggered by opioid use. The epidemiologic case-crossover design lends itself to answering such questions. Rather 121 than traditionally answering “Why this outcome?” the case crossover answers “Why now?” More specifically, the case-crossover design was developed in order to study time-variant exposures associated with what might be experienced as a transient increased risk for some health outcome (82). The leading strength of this design is that time-invariant confounders are controlled for since cases serve as their own controls (e.g., genetic and other individual-level susceptibility traits that pre-date the intervals of experiences under study). Equally, when focused on issues of drug dependence, the case crossover minimizes selection bias often introduced by the tendency to rely on non-drug using controls (82). As a result, this design has been popular within drug dependence epidemiology (83)(84)(85)(86). Case crossover methodology relies on pre-specified ‘hazard’ intervals (i.e., excess odds of an exposure) versus ‘control’ intervals (i.e., exposure odds at expected values), generally of equal duration in time (t) and aligned in relation to a hypothesized latency period (87). In respect to this study, t represents the time passing – e.g., after an interval of newly incident heroin use when individuals may be at an increased risk to begin newly incident stimulant use. There is scant literature on an estimated latency period between heroin use onset and stimulant use onset, but there are hints that there might be short latency. On this basis, and guided by research suggesting that prolonged opioid use can result in sleep changes in as little as six weeks (88), the hazard interval was set to two months just prior to the month of starting to use psychostimulants extra-medically, where ‘extra-medical’ refers to using a stimulant outside the boundaries of prescribed indications (e.g., for feeling states such as ‘to get high’). Given that sleep disturbances contribute to feelings of fatigue, the hypothesized intervals were chosen based on the premise that heroin users may be more likely to increase energy levels with a stimulant within two months after starting to use heroin. 122 As noted below, it is important to specify the hypothesized latency period in advance of inspecting the temporal sequences in the study data. However, it has become customary to conduct ‘post hoc’ sensitivity analyses with other intervals in order to examine how robust or fragile the estimated associations might be across a range of alternative specifications. For this reason, in a post hoc analysis clearly labeled as an exercise of post-estimation exploration of alternatives, the 1-month hazard and control interval was considered in this study, as are other alternatives. Akin to prior case-crossover research on the cannabis-cocaine relationship (83), this case crossover study spans two distinct drug subtypes in order to understand possible drug-using trajectories. In this instance, extra-medical psychostimulant use can be considered as a consequence of NIHU, concurrent with consideration of NIHU as a trigger for new onsets of extra-medical stimulant use. This study aims to investigate the degree to which onset of heroin use may precipitate excess risk of onset of stimulant use. Figure 12. Diagram of Case Crossover Design Studying Newly Incident Heroin Use and Excess Risk of Newly Incident Stimulant Use. Newly Incident Heroin Use? Hazard Interval Newly Incident Heroin Use? Control Interval Exposure Outcome Newly Incident Stimulant Use 1 2 3 4 Time (months) 0 *Study design proposed by Maclure (1991) to study transient effects on the risk of acute events. Working backward from the month ‘t’ of onset of extra-medical stimulant use to the two-month hazard interval and the two-month control interval. Estimation based on how often heroin onset has occurred in the hazard interval but not in the control interval (evidence that favors a non-null ‘triggering’ hypothesis) versus how often heroin onset has occurred in the control interval and not in the hazard interval (evidence that favors a ‘null’ hypothesis of no triggering. Link available: https://www.ncbi.nlm.nih.gov/pubmed/1985444 Stimulants include prescription stimulants (e.g., amphetamines) and cocaine, as well as ‘ice’ and other forms of non-prescription methamphetamines. 123 6.2 Methods Study Population: The study population for this epidemiological research consists of non-institutionalized civilian residents of the 50 States and the District of Columbia, age 12 years and older, living within the United States (US) during 2002-2016. Sample: Each year, research staff for the US National Surveys on Drug Use and Health secured a new probability sample of the study population and administered computer-assisted self-interviews to assess health topics. Staff created de-identified public use files (PUF) for each year. All work complied with institutional review board–approved protocols. The US Department of Health and Human Services Center for Behavioral Health Statistics and Quality created NSDUH open access analysis files with de-identified data after applying disclosure analyses designed to prevent re-identification of participants. Given the circumstances of open access and no contact with participants, the Michigan State University institutional review board ruled that plans to analyze these data qualified for the federal category “not human subjects research.” Aggregate NSDUH files included 837,326 participants, including those identified as extra-medical users who started newly incident stimulant use (NISUs) during the 12 months prior to survey assessment. Here, stimulant refers to prescription stimulants (e.g., amphetamines, methylphenidate), cocaine, and derivative compounds. NISUs were assessed within 12 months after first use, excluding all past users. For case-crossover estimation purposes, the informative NISUs who contribute to the odds ratio estimation of relative risk are those with newly incident heroin use (NIHU) during either the hazard interval or the control interval (i.e., within one to four months of NISU onset, extra-medically). Participants with NIHU and NISU within the same month were dropped from the analysis to be more certain that heroin use preceded stimulant use. 124 Statistical Analysis: Prespecified control and hazard intervals were each set equal to two months a priori, as explained in the study introduction. ‘Evidence favoring’ NISUs were considered to be stimulant users who started to use heroin within the hazard interval but not the control interval. ‘Evidence not favoring’ NISUs were EM NISUs who started to use heroin within the control interval but not during the hazard interval. Counts of these ‘evidence favoring’ and ‘evidence not favoring’ NISUs were tabulated by study year and then were used to calculate discordant pair ‘exposure odds ratios’ (ORs) based on matched pair contingency tables. A Stata software command “mcci” produced estimated OR based on dividing the two counts as just described. Meta-analyses were conducted across the 15 NSDUH study years 2002-2016, which can be considered as independent replication samples of the US study population as characterized at the start of this section. Meta-analysis summary estimates required log transformations for asymmetrical confidence intervals (CI) and a random effects estimator was used to capture heterogeneity across year-specific OR estimates. Analyses were repeated with analysis-weighted counts using Taylor Series Linearization for variance estimation (i.e., Stata ‘svy’ command). Stata SE software (StataCorp, LLC) and ‘svy’. Additionally, to explore the degree to which the unweighted OR estimates might have been influenced by factors controlled in the analysis weights (age, sex, race, probability of selection), a stratified analysis without weights was completed, with strata defined by quartiles of the analysis weights. The expectation was that the OR estimates would not show appreciable variation across these strata. Finally, as noted above, a post-estimation set of exploratory data analyses looked into the issue of specifying the latency period. These post hoc analyses estimated discordant pair odds ratios based on a range of hazard and control interval widths, t. Four alternative specifications were considered, involving intervals of one, three, four, and six months. 125 Table 51. Characteristics of Newly Incident Stimulant Use Sample. Data from United States National Surveys on Drug Use and Health, 2002-2016. NISUs w/ Lifetime Heroin Case Crossover Sample** NSDUH 2002-2016 n=837,326 n (%) Use n=3,696 n Male 401,270 Characteristics Sex Age Groups (Years) 12-17 18-25 26-34 35-49 50-64 65+ Ethnic Self-Identification* White Black/African American Native American/Alaskan Native Hawaiian/Pacific Island. Asian >1 Ethnicity Hispanic 258,309 263,258 93,449 128,684 56,998 36,628 532,503 106,106 12,284 4,042 30,449 26,309 134,633 Extra-Medical Prescription Opioid History Lifetime Use (>12 Mon.*) Within 12 Mon.* Never Used Missing Data 67,677 53,527 614,389 101,737 (%) (69) (3) (27) (29) (26) (14) (0.6) (76) (10) (0.8) (0.3) n=579 n 396 29 116 47 155 203 29 416 66 12 4 (%) (74) (0.8) (4) (6) (24) (60) (6) (69) (15) (0.7) (0.2) (0.7) (2) (11) (28) (54) (14) (3) 6 15 60 161 200 173 45 (2) (0.5) (13) (4) (8) (75) (13) 2,248 332 1,979 690 528 156 11 2,845 192 67 20 31 149 392 888 2,285 430 93 (48) (10) (13) (14) (25) (22) (16) (67) (12) (0.5) (0.3) (5) (1) (14) (8) (4) (75) (13) 126 NSDUH Downloadable Public Use Data. NISUs: Newly incident stimulant users first used within 12 months of survey assessment. Past onset users excluded. Stimulants include amphetamine, methamphetamine, or cocaine. Unweighted n’s, weighted percentages. *Ethnic self-identification: all ethnicities other than Hispanic are specified as non-Hispanic per survey assessment. ** NISUs who are discordantly informative for estimation of OR - participants either started heroin use in the hazard interval or in the control interval. All other NISUs excluded. Table 52. Counts and Discordant Pair Odds Ratios of Newly Incident Heroin Use Preceding Newly Incident Stimulant Use. Data from United States National Surveys on Drug Use and Health, 2002-2016. Discordant Pair Odds Ratios Heroin Exposure Intervals Control Int. Hazard Int. n (%)a n (%)a Unweighted OR (95% CI) Weighted OR (95% CI) 1 (47) 3 (45) 3 (100) 29 (93) 25 (40) 23 (41) 20 (54) 28 (37) 30 (61) 17 (49) 15 (27) 21 (48) 29 (63) 21 (61) 21 (43) 289 (55) -- Year 1 (53) 2002 0 (55) 2003 1 (0) 2004 37 (6) 2005 25 (60) 2006 22 (59) 2007 30 (46) 2008 17 (63) 2009 20 (39) 2010 37 (51) 2011 20 (73) 2012 15 (52) 2013 23 (37) 2014 24 (39) 2015 21 (57) 2016 293 (45) Pooled Metab -- NSDUH Downloadable Public Use Data. Outcome: stimulants: methamphetamines, amphetamines, or cocaine. Hazard and control intervals equal 2 months set a priori. aUnweighted n. Weighted percent. bMeta-analysis summary estimates use log transformation. Estimates rounded to tenths place. Unweighted: I2=10.6%, p>0.05, MA=1.001, 95% CI=0.840, 1.194 Weighted: I2=82.6%, p<0.001, MA=1.048, 95% CI=0.788, 1.394. with random effects. <0.1, 78.5 -- 0.2, 157.5 0.5, 1.3 0.6, 1.8 0.6, 2.0 0.4, 1.2 0.9, 3.2 0.8, 2.8 0.2, 0.8 0.4, 1.5 0.7, 2.9 0.7, 2.3 0.5, 1.6 0.5, 1.9 0.8, 1.2 0.8, 1.2 0.6, 1.3 0.5, 1.2 -- 6.9, 43.3 0.4, 1.0 0.5, 1.1 0.8, 1.8 0.4, 0.9 1.0, 2.4 0.6, 1.5 0.2, 0.6 0.6, 1.4 1.1, 2.6 1.0, 2.4 0.5, 1.1 0.8, 1.9 0.8, 1.4 0.9 0.8 -- 15.5 0.7 0.7 1.2 0.6 1.6 1.0 0.4 0.9 1.7 1.6 0.8 1.2 1.0 1.0 -- 3.0 0.8 1.0 1.0 0.7 1.6 1.5 0.5 0.8 1.4 1.3 0.9 1.0 1.0 1.0 127 Table 53. Post Hoc Interval Width Exploration: Unweighted Discordant Pair Odds Ratios of Newly Incident Heroin Use Preceding Newly Incident Stimulant Use. Data from United States National Surveys on Drug Use and Health, 2002-2016. 6 months 3 months 4 months 1 month Cases n=573 OR Cases n=1,001 OR Controls n=1,188 95% CI 0.4 0.5 0.9 1.3 1.2 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.7 0.6 0.6 0.8 0.9 0.1, 1.6 0.1, 1.6 0.2, 3.0 0.9, 1.7 0.9, 1.6 0.9, 1.7 0.8, 1.5 0.8, 1.4 0.6, 1.2 0.6, 1.1 0.5, 0.9 0.4, 0.8 0.5, 0.9 0.4, 0.8 0.4, 0.9 0.8, 0.9 0.7, 1.0 Cases n=457 OR Cases n=168 OR Controls n=119 95% CI Controls n=568 95% CI 0.1, 118.0 0.2, 18.0 0.3, 22.1 0.6, 1.5 0.5, 1.1 0.4, 0.9 0.5, 1.2 0.4, 0.9 0.7, 1.7 0.5, 1.2 0.4, 1.0 0.4, 1.2 0.9, 2.2 0.5, 1.4 0.5, 1.5 0.7, 0.9 0.7, 0.9 2.0 1.5 2.0 1.0 0.7 0.6 0.8 0.6 1.1 0.8 0.6 0.7 1.4 0.9 0.9 0.8 0.8 -- 0.5 0.5 1.6 1.0 2.8 1.2 1.5 1.7 1.4 6.5 1.1 1.2 0.8 1.1 1.4 1.3 Year 2002 -- 2003 <0.1, 9.6 2004 <0.1, 9.6 2005 0.7, 3.8 2006 0.5, 2.6 2007 1.1, 8.8 2008 0.5, 3.3 2009 0.7, 3.7 2010 0.8, 4.0 2011 0.5, 4.4 2012 1.5, 59.3 2013 0.4, 2.9 2014 0.6, 2.8 2015 0.3, 2.1 2016 0.4, 2.9 Pooled 1.1, 1.8 Meta* 1.0, 1.7 NSDUH Downloadable Public Use Data. Post hoc analysis explored interval width. A priori interval width set to 2 months. Estimates are unweighted and rounded to the tenths place. -- due to zero cells. *Meta-analysis summary estimates use log transformation. 1month: I2=8.78, p>0.05, MA=1.33, 95% CI=1.020, 1.735 3month: I2=15.6%, p>0.05, MA=0.807, 95% CI=0.709, 0.919 4month: I2=39.0%, p>0.05, MA=0688, 95% CI=0.614, 0.771 6month: I2=61.5%, p<0.001, MA=0.853, 95% CI=0.729, 0.997 with random effects. 1.0 1.5 1.0 1.0 0.6 0.6 0.6 0.4 0.8 0.7 0.5 0.7 0.9 1.0 0.8 0.7 0.7 Controls n=826 95% CI 0.1, 13.8 0.2, 18.0 0.2, 5.4 0.7, 1.5 0.4, 0.9 0.4, 0.9 0.4, 0.9 0.3, 0.6 0.6, 1.2 0.5, 1.0 0.3, 0.7 0.4, 1.1 0.6, 1.3 0.6, 1.5 0.5, 1.2 0.6, 0.8 0.6, 0.8 128 Table 54. Year-Specific Numbers of NISUs Stratified by Analysis Weight Quartiles and Interval-Specific Exposure Status. Data from United States National Surveys on Drug Use and Health, 2002-2016. Quartile 1 0 > x £ 61.8 Quartile 2 Quartile 3 61.8 > x £ 134.1 134.1 > x £ 337.2 Quartile 4 > 337.2 0 0 0 11 8 4 3 6 4 2 2 5 2 3 0 50 0 0 0 9 6 4 2 3 5 7 3 4 5 4 2 54 0 1 0 4 5 4 4 5 3 3 4 8 9 2 5 57 0 0 1 2 4 4 2 3 5 2 0 1 1 2 1 28 Year 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Totals Hazard Control Hazard Control Hazard Control Hazard Control 1 0 0 19 12 10 21 7 8 22 12 8 8 16 15 159 0 0 1 6 6 3 2 6 9 3 2 2 5 1 2 48 NSDUH Downloadable Public Use Data. Outcome: stimulants: methamphetamines, amphetamines, or cocaine. Hazard and control intervals equal 2 months set a priori. Control interval: heroin first use within 3 or 4 months of stimulant first use. Hazard interval: heroin first use within 1 or 2 months of stimulant first use. Estimates rounded to tenths place. Unweighted counts stratified by analysis weight quartiles indicate how many NISUs were exposed and had first heroin use in the hazard interval but not in the control interval (shown in the columns labeled ‘Hazard’ and how many NISUs were exposed and had first heroin use in the control interval but not in the hazard interval (shown in the columns labeled ‘Control’. 1 2 2 8 6 12 11 11 14 9 7 6 13 15 14 131 | 0 0 7 3 4 5 4 2 6 5 2 9 2 3 52 129 Table 55. Year-Specific Odds Ratios of NISUs Stratified by Analysis Weight Quartiles and Interval-Specific Exposure Status Data from United States National Surveys on Drug Use and Health, 2002-2016. Quartile 1 0 > x £ 61.8 95% CI Quartile 2 Quartile 3 134.1 > x £ 337.2 OR 95% CI OR OR -- -- -- 5.5 2.0 1.0 1.5 2.0 0.8 1.0 -- 5.0 2.0 1.5 -- 1.8 1.6 61.8 > x £ 134.1 OR 95% CI Year -- -- 2002 -- -- 2003 -- -- 2004 0.2, 2.1 0.7 2005 0.3 3.7 1.0 2006 0.1 4.4 0.8 2007 0.1, 13.8 1.0 2008 0.4, 12.4 2.0 2009 0.5, 6.8 1.8 2010 0.1, 1.9 0.4 2011 0.7 0.1, 5.8 2012 0.5 <0.1, 3.5 2013 1.0 0.2, 4.3 2014 0.3 <0.1, 2.5 2015 1.0 0.1, 13.8 2016 0.6, 1.3 0.9 Pooled Meta* 0.8 0.5, 1.3 NSDUH Downloadable Public Use Data. *Meta-analysis summary estimates use log transformation and random effects estimator. Estimates rounded to tenths place. -- represent zero cells. -- -- -- -- -- -- 0.1, 2.2 0.6 1.7 0.3, 10.7 0.2, 5.4 1.0 0.8 0.2, 3.7 0.8 0.2, 3.7 1.5 0.2, 18.0 0.1, 2.3 0.5 0.8 0.2, 3.7 4.0 0.8, 38.7 1.0 0.4, 2.8 1.0 0.1, 13.8 1.7 0.3, 10.7 0.7, 1.6 1.1 1.0 0.6, 1.6 -- -- -- 1.2, 51.1 0.5, 9.1 0.2, 5.4 0.2, 18.0 0.4, 12.4 0.2, 3.7 0.1, 13.8 -- 0.6, 236.5 0.1, 118.0 0.2, 18.0 -- 1.1, 2.9 0.9, 3.0 Quartile 4 x > 337.2 95% CI 1.0 <0.1, 78.5 -- -- -- -- 0.2, 1.0 0.4 0.2, 1.4 0.5 0.5, 3.1 1.2 0.2, 1.1 0.5 1.6 0.6, 4.8 0.7, 4.8 1.8 0.2, 0.9 0.4 0.2, 1.6 0.6 0.8 0.2, 2.5 0.6, 4.5 1.6 0.4, 2.0 0.9 0.9 0.4, 2.0 0.6, 1.0 0.8 0.8 0.6, 1.1 6.3 Results Based on the discordant pairs within the NISU sample of informative 579 participants, the hazard interval included 289 individuals with heroin onset within the hazard interval (one or two months prior to NISU), but not in the control interval (Table 52, bottom rows). The control interval included 293 individuals with heroin onset within the control interval (three to four months prior to NISU) but not in the hazard interval. Year-specific estimates are not appreciably different, except in years with small numbers of informative NISUs (0 to 3 individuals). Year-specific unweighted ORs are not statistically significant and show both weakly positive and inverse associations (Table 52). Across study years 2002-2016, a meta-analysis and 130 a pooled analysis yielded ORs=1.0 (95% CIs=0.8, 1.2). Year-specific ORs with analysis weights applied also show both positive and inverse associations. ORs for study years 2005 and 2014 are statistically significant (OR=15.5, 95% CI=6.9, 43.3; OR=1.7, 95% CI=1.1, 2.6). Across study years 2002-2016, a pooled analysis yielded OR=1.2 (95% CI=0.8, 1.9). A meta-analysis yielded OR=1.0 (95% CI= 0.8, 1.4). Post hoc exploration suggests that a 1-month interval specification might be useful in future case-crossover research of this type. The exploratory OR based on the 1-month interval specification show a weakly positive association (OR=1.3, 95% CI=1.0, 1.7) (Table 53). Exploration of other interval specifications suggested null associations. Similarly, in stratified analyses with quartiles based on analysis-weights, the general pattern is one of a null case- crossover relationship and evidence that does not favor the triggering hypothesis as proposed. 6.4 Discussion The ‘a priori’ latency period was specified in relation to two successive two-month intervals working backward from the calendar month of first newly incident extra-medical use of stimulant drugs (i.e., t-1 and t-2 months as hazard interval, t-3 and t-4 months as control interval). This specification produced a null odds ratio estimate and the result does not support a hypothesis of heroin onset triggering extra-medical onset of stimulants drugs. Looking over the post hoc exploratory data analysis results, it appears that a better choice for the duration of the latency interval is ‘one month’ in that the first month after NIHU appears to be a month of excess risk of newly incident extra-medical stimulant use (OR> 1.0; p<0.05). All other specifications suggest null (or possibly inverse) associations. Moreover, in the stratified analyses, individuals with the lowest possible analysis weight values seem to be of interest (i.e., NISUs who live alone and others in the first analysis weight 131 quartile). For this quartile, there is evidence of an OR estimate that departs from the null, unlike other analysis weight quartiles. It is important to consider limitations. For example, in research of this type, even with recall restricted to fairly memorable events that have occurred within 12 months prior to the assessment, it is not possible to rule out correlated recall error related to an individual’s remembered drug use history. A spurious association could result from systematic error in reporting hazard interval versus control interval information. For example, individuals who remember using heroin shortly before using stimulants may recall these events being in adjacent months (i.e., one-month interval). Differential misclassification of this sort can lead to conclusions for or against the null (87). Furthermore, a potential threat to validity with case crossover designs is related to mis- specified hazard and control intervals. In theory, the interval duration should reflect the minimum induction period (Figure 14) (87). If this interval is incorrectly specified, the result can be non-differential exposure misclassification and a potentially attenuated OR estimate (87). A third limitation involves elimination of participants for whom a single calendar month was stated as the month of first extra-medical stimulant use and also the month of first heroin use. These participants were judged non-informative because the NSDUH does not ask about ordering of stimulant and heroin use when both onsets occur in the same calendar month. It is not possible to say whether the heroin use came first within the month, or vice versa. As such, it is possible for heroin onset to trigger extra-medical use of a stimulant with a very short latency or induction period (shorter than the 1 month period specified here as the lowest possible value). This limitation can be overcome only if very fine-grained data about temporal sequencing is available. For example, when the same calendar month is stated, the user might be asked 132 questions about which came first, as well as questions about the interval of time separating the two onsets. A fourth possibility is differential loss of the most seriously drug-involved users in probability samples of community populations. That is, non-participation might be a more serious threat to validity for individuals who rapidly progressed from heroin use to extra-medical stimulant onset, as compared with individuals who made no such progression. Lastly, among limitations, the current study relies on annual nation-scale cross-sectional field surveys. It is possible that the attempt to secure nationally representative samples of newly incident drug users might introduce study artifacts that are not faced when alternatives are considered such as ‘snowball’ or ‘respondent-driven’ sampling (RDS). Leaving aside any concerns about snowball or RDS approaches, in the context of national cross-sectional surveys, this facet of study design introduces concerns about artifacts akin to left truncation and left censoring processes in follow-up studies. These are processes that can constrain valid enumeration of NISUs and NIHUs in samples of this type, especially for those in which NIHU follows NISU quickly, or vice versa. Larger samples would make it possible to focus the ‘newly incident’ interval on persons observed within 0-90 days after first stimulant onset. This manipulation of study design can reduce these theoretical processes akin to left-truncation and left-censoring as observed in longitudinal time-to-event studies, and it should be noted that neither ‘snowball’ nor RDS approaches will avoid these issues and concerns. At present, drug dependence epidemiology, even when it has turned to snowball or RDS approaches, has produced no particularly useful estimates of the ‘instantaneous risk’ of dying from overdose, being incarcerated, or migrating quickly across community dwelling units. It would be these ‘instantaneous risk’ estimates that would help to better understanding of these sources of bias in study estimates of the type reported here. 133 Notwithstanding said limitations, there may be importance in the one-month interval specification, coupled with the non-null OR seen in exploratory analyses stratified by quartile of analysis weight. As described previously, one of the major determinants of the analysis weight is the number of eligible participants within the sampled dwelling unit, with the largest selection probability (1.0) assigned to those who live by themselves. One might speculate that there is a feedback loop between living alone and rapid progressions from one drug to another – i.e., that the living alone followed drug use rather than preceded drug use. However, it also is true that living alone might influence density of chances to try a stimulant after first heroin use. Living alone might imply reduce social sharing of drugs and thus there might be a less rapid transition from heroin to stimulant user in this stratum. These are speculations that will require more empirical research before a complete understanding of the relationships linking the current opioids crisis with an emerging epidemic of extra-medical psychostimulant use in the US. The current study is the first of its kind and there was no prior literature on this topic, as might have been used to guide its specification of optimal latency period. Based on this work, an optimal choice might be the one-month interval. 134 Figure 13. An epidemic curve for acute-onset disease following a point exposure. Study design proposed by Maclure (1991) to study transient effects on the risk of acute events. Link available: https://www.ncbi.nlm.nih.gov/pubmed/1985444 6.5 Conclusions It was hoped that the current study would shed new light on transitions from newly incident heroin use to newly incident extra-medical use of psychostimulant drugs. Likewise, this information could have helped to understand the current US opioids crisis and the emerging pattern of increased incidence rates for use and outcomes related to extra-medical use of psychostimulant drugs. Based on prior case-crossover research (cited above), it was possible to conceptualize a theoretical possibility that heroin onsets might trigger onsets of extra-medical use of these stimulant drug compounds, and to specify a hypothesized latency period of two months for the case-crossover hazard and control intervals in the life of each newly incident stimulant user. Conversely, there is not strong evidence supporting idea that heroin onset triggers onset of extra-medical use of stimulant drugs. The implication is that there is some other process that helps explain what happened in the epidemiology of heroin and stimulants use back in the 1960s 135 through 1980s and what now is happening in the epidemiology of heroin and stimulants use in the first decades of the 21st century. It is important to remember that studying etiological processes do not lend themselves to individual implications, such as clinician recommendations for patients. In the context of generally null findings, clinical practitioners and counselors should look elsewhere for insights as might guide intervention plans for their patients and clients. Having said that, based on this work, the imminent risk of starting extra-medical use of cocaine or amphetamine or one of the other psychostimulants is not something the practitioner should be especially concerned about. Instead, the implications of this research are for future epidemiological research into the heroin-stimulants relationship. First, if other case-crossover designs are contemplated, a starting point can be a 1-month interval as opposed to a two-month interval for the hypothesized latency period. Plus, there is reason to think through the possibility that the association can be seen most prominently among individuals who are living alone, or who have other weight-influencing characteristics that prompt their membership in the lowest quartile of NSDUH analysis weights. In this respect, the discovery of null OR estimates in this dissertation research project’s case-crossover investigation can be informative. As it pertains to epidemiology, more than a few steps forward have been taken. There is new evidence and methodological considerations for guidance of future research on the epidemiology of heroin use and its potential consequences. With respect to the title of this chapter, the null findings might suggest that the individual-level processes of starting extra-medical stimulant use soon after heroin onset are irrelevant to the epidemiological processes that can be seen in trends. The evidence from discordant pair odds ratio estimates of this study should not lead to any premature disruption about ideas that link an earlier opioids epidemic with a later stimulant epidemic. The evidence of this study pertains to highly individualized experiences of the newly incident stimulant users in 136 this nation-level sample. It does not exhaust all of the possibilities for either individual-level or macro-level processes that produce a sequence from an opioids epidemic to a stimulant epidemic. There is good reason to conceptualize heroin-stimulant sequences that are prompted by a common underlying susceptibility trait of the type that is completely controlled in the case- crossover design (81-85). Alternately, there are supra-individual processes that operate on more of a macro-level of influence (e.g., drug regulatory and enforcement processes), some of which have been mentioned in the context of ideas about social sharing of drug compounds from one individual to another in socially connected groups. Other processes can be operating at a supra- individual level, as might be the case in the hypothesis that a black-market stimulants vendor might study patterns of heroin/opioids overdose and use, community by community, and selectively target communities with emerging problems as manifest in opioids overdoses or arrest rates. Given the common practice of using geo-coded ‘Google Trends’ and other internet- mediated information to target zones of susceptibility for consumer purchases or social sharing of information, it is not difficult to imagine that black-market vendors might start to use these new elements of information about geographical clustering of ‘opioids’ mentions in order to make decisions about marketing of stimulants. These are epidemiological and social processes that would tend to connect the opioids experiences of US civilians with the stimulant experiences of US civilians. A case-crossover study of this type would not disclose these processes of ‘precipitation’ of a stimulants outbreak in the aftermath of an opioids outbreak, and would not disclose an opioids epidemic giving rise to a stimulants epidemic. 137 CHAPTER 7 DISCUSSION AND CONCLUSIONS 7.0 Summary of Findings Aim 1: Aim 1 findings focus on estimation of the pairwise associations between problems and experiences of heroin use disorder interval by interval beginning from the first months of use. The most common PEs experienced among NIHUs are trying to set limits, having problems with emotions, spending a lot of time getting or using heroin, needing more to get the same effect, having problems with family or friends, and spending less time doing important activities. Throughout time intervals, the majority of PE to PE odds ratios are robust, positive, and are statistically significant departures from the null (OR=1.0). These large associations and wide confidence intervals likely reflect maldistribution within contingency tables and exchangeability between PEs. Notable exceptions within 0-90 days of first using heroin include inverse, but not statistically significant, associations between cutting down at least once and trying to set limits, spending a lot of time getting or using, having problems with family or friends, continuing to use despite problems with emotions, physical danger, continuing to use despite problems with family or friends, and being unable to keep limits. Inverse associations may indicate that the PE of cutting down at least once is not a signal of HUD but is a signal of being less dependent. Continuing to use despite having physical problems has no association with any PEs. Within 1- 120 days of first using, cutting down at least once does not have as many inverse associations – an inverse association between that and needing more for the same effect and physical danger. Having physical problems, continuing to use despite physical problems, trouble with the law, and spending a lot of time getting over the effects are not shown to be associated with any PEs. Within 30-150 days, more inverse associations are seen related to cutting down at least once, continued use despite problems with emotions, spending less time doing important 138 activities, having problems with family or friends, and spending a lot of time getting or using. A similar pattern of inverse association with the PE cutting down at least once is seen within 60- 180 days of first using. Having physical problems also inversely correlates with spending less time doing important activities, being unable to set limits, and spending a lot of time getting over the effects of heroin during this time frame. A possible explanation is heterogeneity in those with HUD in that physical problems is not at a severity where the associated PEs would be experienced. Within 90-120 days of first using heroin, spending a lot of time getting over the effects of heroin, having physical problems, and continuing to use despite having physical problems is not associated with any PEs. A similar pattern is seen within 120-240 days of first using. Notably, a departure from the pattern occurs during 150-270 days of first using. Continued use despite having physical problems is robustly and significantly associated with spending a lot of time getting or using, needing more to get the same effects, having problems with family or friends, spending less time doing important activities, physical danger, continuing to use despite problems with family or friends, and trouble with the law. The 150-270-day time interval reveals the first occurrence of large, statistically significant associations with continuing to use despite having physical problems. Yet, there are null associations with the PE within subsequent lag- time intervals. Most likely this is due to small cell counts within continuing to use despite physical problems, which is also the least common PE. With 180-300 days of first using heroin, inverse associations are seen between PEs spending a lot of time getting over the effects, the same amount having less effect, having problems with family or friends, spending less time doing important activities, and continuing to use despite having problems with emotions. Within 210-330 days of first using heroin, inverse association appear between pairs related to use causing serious problems, having three or more 139 withdrawal symptoms and having them at the same time, and spending a lot of time getting over the effects and needing more to get the same effect. Likewise, there are inverse associations between cutting down at least once, trying to set limits, needing more to get the same effect, and the same amount having less effect within 240-360 days of incident use. These associations are not statistically significant though. Within 270-330 days of first using, there are several inverse associations related to trying to set limits. This may signal that trying to set limits has a meaning related to a less severe form of dependence or showing a departure from the use disorder. This trend is not seen in the intervals of 300-420 and 330-450 days within first use. Aim 2: The evaluation of measurement equivalence from aim 2 confirms methodologically important and interesting details about the NSDUH assessment of diagnostic criteria for HUD and evaluation of HUD levels. First, study of sex differences in HUD level seems to require no more calibration of the measurements under the specified models. Second, measurement calibration will be needed if the aim is to estimate HUD variation across types or levels of prior opioids-using experiences. Aim 3: Aim 3 investigating the degree to which onset of heroin use might precipitate excess risk of stimulant use onset, produced a null finding with the a priori specification of a 2- month latency period. Post-estimation exploratory analyses indicate that future research might be improved by substituting a 1-month interval in place of the 2-month interval used in this study. 7.1 Strengths and Limitations The current study relies on NSDUH annual cross-sectional surveys intended to yield nationally representative samples. There are three limitations intrinsic to this study design: 1) Left truncation and left censoring may underestimate the number of NIHU. To directly combat challenges of left truncation and censoring, the newly incident heroin use case definition (i.e., within 12 months of assessment) restricts the amount of time participants have to develop HUD- 140 related experiences that would keep them from being sampled or completing the interview (e.g., incarceration, fatal overdose). Even so, considering the ratio of newly incident heroin users to those who die of heroin overdose in the first year of use, potential left truncation is negligible. The same is true of left censoring when reflecting on those incarcerated within the first year of use. 2) The study’s reliance on self-report merits attention, yet there is currently no feasible alternative for surveys assessing history of drug use. 3) Cross-sectional surveys are often criticized for limited temporal sequencing. Notably, the current study circumvents this issue given participants cannot develop heroin use disorder without first having tried the drug. Inferences relating to the natural history of HUD within aim 1 are limited in that there cannot be a causal interpretation of PE to PE relationships. A strong association between PE pairs may indicate that those PEs are measuring the same underlying construct such as HUD or HUD-related diagnostic criteria. Aim 1 does shed light on the coalescence of problems and experiences associated with HUD and how that may change as individuals have had more time to develop HUD. Causal inferences are also limited as they pertain to aim 3. It cannot be said that heroin use causes an individual to start using heroin. Likely, there are circumstantial experiences that may make a NIHUs more susceptible to start using another drug. Also, given prescription stimulants and cocaine were combined into one stimulant category, it is unknown if there is a particular drug driving some association or attenuating an association. Additionally, aim 2 can only offer the recommendation that EMPOU may differentially influence HUD measurement. More work needs to be done in order to understand where the subgroup differences are located and what the effects are. 7.2 Public Health Implications and Next Steps The future of heroin-related research and public health implications are areas that would greatly benefit moving forward intertwined with each other. That is, I believe that ethically, there 141 should be no study to understand heroin use without simultaneously intervening since the heroin- related overdose mortality rate is unprecedented and the epidemic proportions of use can be linked to highly morbid sequalae (e.g., HIV/AIDS). Moreover, providing participants with more than incentives for participation, but actual resources, knowledge, and care should be the new IRB-gold standard. An intriguing and new area of intervention research is citizen science. Often citizen science is in conjunction with crowdsourcing, which may be a useful way to gauge a given community’s severity of heroin use and use disorder. Important additives may then include community-based reaction to the gauged severity based on a matrix of options (Figure 15). An important goal of citizen science is recruiting community members not as participants, but as collaborators in science to allow sustained program dissemination. For example, a multi-step process may require citizen education and focus-group feedback. A D2L (desire to learn) module could walk community members through naloxone administration, clean needle exchange and proper disposal methods, and effective communication strategies, to name a few. Following education, researchers can meet with those citizens to assess their understanding and figure out how those tools can be implemented in their community. Michigan State University Extension throughout Michigan is a possible mechanism for this cycle. 142 Figure 14. Infographic Exerts for Citizen Science-Based Initiative Graphics from www.infogram.com Furthermore, citizen science could benefit from integrated harm reduction initiatives. Aside from clean needle exchange, “open air” or safe spaces for injection should be provided within a community. There, citizens trained in naloxone administration could support those using heroin and help provide resources to users such as clean needles, connections to treatment, and 143 aid in recovery from heroin use. A “safety kit” including drug test kits, fentanyl test strips, condoms, pregnancy tests, alcohol swabs, naloxone, and hand sanitizer could be available and would minimize morbidity and mortality. Relatively more distal points for intervention may consider intervening within families. Adverse childhood events have been shown to be linked to adverse health outcomes in adulthood, including non-fatal overdose among individuals who inject drugs (49). Thus, family intervention may mitigate future generations of drug use. Additionally, families with adverse events may include drug-using parents in need of intervention. Family interventions should help parents with resources and execution of effective parenting (e.g., parent-child communication, help with obtaining affordable childcare). Such efforts may not have direct aims in heroin use prevention but may indirectly influence heroin use through more well-adjusted child rearing and community engagement. Importantly, intervention strategies outlined above should be coupled with clinician supervised medication substitution or assisted treatment psychological counseling. Results from aim one directly speak to clinicians for evidence-based screening recommendations. That is, strong PE to PE odds ratios indicate which questions should be asked if a patient has experienced newly incident heroin use. Clinicians can identify cases of HUD by asking two questions based on individual’s experiences in order to determine if a psychiatric consultation is needed. Evidence-based screening methods such as this are not currently available to clinicians and will allow for more accurate and timely HUD identification. Likewise, as problems with emotions emerged as an early and robust correlate within PE to PE ORs, mood disturbances may need to be a more central focus for identifying newly incident heroin use. To dovetail possible evidence-based screening for clinicians, evidence-based interactive journal logs are a possibility. For example, individuals could download an anonymous 144 mobile phone application allowing them to log their health experiences including drug use. The app could provide feedback ranging from universal recommendations such as staying hydrated and getting sleep to recommendations to meditate during mood disturbances. Logging information regarding newly incident heroin use and subsequently logging of emotional problems could elicit the application to provide treatment options and encourage the individual to seek local counseling. Some of the aforementioned interventions have structural barriers which make them particularly difficult for this population, as individuals who use heroin may be homeless and without health insurance. Similarly, users in poverty many not be able to afford transportation needed to make it to appointments or users may be incarcerated due to criminalization of heroin possession. Changing structural barriers may include educating the judicial system by talking with judges about drug court programs. Counseling via telephone or online chat could be a potential option. Even further, peer-based counseling could mirror Alcoholics Anonymous’ sponsors by pairing users with educated citizen science representatives to provide emotional support. Additional creative approaches to overcoming structural barriers to HUD treatment should be explored. 7.3 Conclusions Drug dependence epidemiology and specifically that of heroin have quickly gained public awareness at a national and global level. Heroin-related overdose and other opioids crises- related morbidity and mortality continue to increase. Even so, scientific knowledge and effective public health prevention strategies of heroin use and use disorder are lacking. The current study may help to move the field forward given it is the first to illustrate the natural history of HUD through the fine-grain stratification of the problems and experiences that develop over time. This dissertation also draws attention to the need for more precise HUD assessment, given that extra- 145 medical prescription opioid use likely influences the progression or interpretation of HUD. This study also suggests there may be a linkage between newly incident heroin use and stimulant use which deserves more attention in future research. Moving forward, it will be important for public health to anticipate drug use trajectories in order to end cycles of drug use and the subsequent morbidity and mortality. 146 APPENDICES 147 APPENDIX A IRB DETERMINATION 148 149 APPENDIX B MANUSCRIPT 1 150 recode hermfu(1/3=1)(4/6=2)(7/9=3)(10/12=4)(else=.),gen(herquarter) replace recher=1 if recher2_b1==1 & quarter==1 & herquarter<5 & herquarter!=. replace recher=1 if recher2_b1==1 & quarter==2 & herquarter>1 & herquarter!=. replace recher=1 if recher2_b1==1 & quarter==3 & herquarter>2 & herquarter!=. replace recher=1 if recher2_b1==1 & quarter==4 & herquarter==4 & herquarter!=. replace recher=1 if recher1_b1==1 drop recher1_b* Table 56. Manuscript 1 - Stata Code //SB usual code - most conservative definition; drop missing mfu /7 don't knows/refused end up in recher==1, yfu must match survey year gen recher1_b1=1 if year==irheryfu gen recher2_b1=1 if irheryfu==year-1 & irherrc<3 gen recher=0 gen nwincher=1 if herflag==0 | recher==1 replace nwincher=0 if nwincher==. *Step2 lagtime gen hermy=ym(irheryfu, hermfu) gen intm=. replace intm=2 if quarter==1 replace intm=5 if quarter==2 replace intm=8 if quarter==3 replace intm=11 if quarter==4 gen intmy=ym(year, intm) gen lagtime=intmy-hermy recode lagtime (-1=1) (0=1) (14/30=.) *Step 3 PEs foreach k of varlist hergtovr herwd3sx herwdsmt herlottm herlimit herkplmt herndmor herlsefx hercutdn hercutev hercut1x hercutev heremopb heremctd herphlpb herphctd herlsact herserpb herpdang herlawtr herfmfpb herfmctd { } *set limit *herkplmt=2 (could not keep limits) recode herkplmt(99=.)(93=.)(91=.)(1 97 98 94=1)(2=2) recode herlimit (99=.)(93=.)(91=.)(2 97 98 94 85=2)(1=1) gen limit=. replace limit=1 if herlimit==1 & herkplmt==2 replace limit=2 if herlimit==1 & herkplmt==1 replace limit=2 if herlimit==2 *cut down *hercutev=2 (could not cut down) recode hercutev (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode hercutdn (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) gen cutdown=. replace cutdown=1 if hercutdn==1 & hercutev==2 replace cutdown=2 if hercutdn==1 & hercutev==1 replace cutdown=2 if hercutdn==2 Code adapted from James C. Anthony NIDA T32 Trainee Research. tab `k' if lagtime<=13 & recher==1 151 Table 56 (Cont’d). **cut down at least once *cut1x: asked Q if hercutev==2 OR hercutev==2 *will have some hetcutdn yes's bc of cutdn/cutev gating recode hercut1x (93=.)(91=.) (2 99 94 97 98 85=2) (1=1) *withdrawal symptoms *herwdsmt=1 (sympt at same time) recode herwd3sx (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode herwdsmt (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) gen withdwl=. replace withdwl=1 if herwd3sx==1 & herwdsmt==1 replace withdwl=2 if herwd3sx==1 & herwdsmt==2 replace withdwl=2 if herwd3sx==2 | hercut1x==2 | cutdown==2 replace herwd3sx=2 if hercutdn==2 | hercut1x==2 *emotions problems recode heremctd (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode heremopb (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) gen emot=. replace emot=1 if heremopb==1 & heremctd==1 replace emot=2 if heremopb==1 & heremctd==2 replace emot=2 if heremopb==2 *physical problems recode herphctd (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode herphlpb (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) gen phys=. replace phys=1 if herphlpb==1 & herphctd==1 replace phys=2 if herphlpb==1 & herphctd==2 replace phys=2 if herphlpb==2 | heremctd==1 | emot==1 | heremopb==1 *physical replace herphlpb=2 if heremopb==1 | heremctd==1 *fam/friends recode herfmctd (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode herfmfpb (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) gen fam=. replace fam=1 if herfmfpb==1 & herfmctd==1 replace fam=2 if herfmfpb==1 & herfmctd==2 replace fam=2 if herfmfpb==2 *get over recode herlottm (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode hergtovr (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) gen gtovr=. replace gtovr=1 if herlottm==2 & hergtovr==1 replace gtovr=2 if herlottm==2 & hergtovr==2 replace gtovr=2 if herlottm==1 Code adapted from James C. Anthony NIDA T32 Trainee Research. 152 recode `k' (1=1) (2 94 97 98 85=0) (else=.) tab `k' if lagtime<=13 & recher==1 Table 56 (Cont’d). *less effect recode herndmor (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) recode herlsefx (99=.)(93=.)(91=.) (2 94 97 98 85=2) (1=1) replace herlsefx=1 if herlsefx==1 replace herlsefx=2 if herndmor==1 | herlsefx==2 //PE frequency * 94="Don't know", 97=Refused, 98=Blank/No Answer foreach k of varlist gtovr herwd3sx withdwl herlottm herlimit limit herndmor herlsefx cutdown hercut1x heremopb emot herphlpb phys herlsact herserpb herpdang herlawtr herfmfpb fam { } *Recode for looping through PEs *ordered by frequency (==1) gen pe1=herlimit gen pe2=heremopb gen pe3=herlottm gen pe4=herndmor gen pe5=herfmfpb gen pe6=herlsact gen pe7=herserpb gen pe8=hercut1x gen pe9=emot gen pe10=herpdang gen pe11=fam gen pe12=limit gen pe13=cutdown gen pe14=herwd3sx gen pe15=herlawtr gen pe16=withdwl gen pe17=herlsefx gen pe18=gtovr gen pe19=herphlpb gen pe20=phys Code adapted from James C. Anthony NIDA T32 Trainee Research. 153 forvalues j=`k'/20{ foreach s of numlist 1(1)13 { capture noisily insheet using "/Users/Samantha/Library Table 56 (Cont’d). //Survey Weights for Pooled Years gen double vestryr=vestr*10000 gen verepyr=verep*10000+year gen nanal_wt=analwt_c/15 svyset verepyr [pweight=nanal_wt], strata(vestryr) singleunit(centered) forvalues i=1/19{ local k=`i'+1 //Analysis weigth quartiles pctile qweight = nanal_wt, nq(4) summarize nanal_wt, detail gen newvar=. replace newvar=1 if nanal_wt>0 & nanal_wt<=61.84667 replace newvar=2 if nanal_wt>61.84667 & nanal_wt<=134.05 replace newvar=3 if nanal_wt>134.05 & nanal_wt<=337.194 replace newvar=4 if nanal_wt>337.194 & nanal_wt!=. forvalues i=1/19{ local k=`i'+1 plain onecell label }}} // or label var egen string pelab = concat(firstpe secondpe), punct(,) // graph or by quartile *gen nlb=0 if lb<0 gen nub=ub replace nub=20 if nub>=20 Code adapted from James C. Anthony NIDA T32 Trainee Research. forvalues j=`k'/20{ foreach s of numlist 1(1)4 { dis "pe`i' pe`j' newvar`s'" capture noisily logit pe`i' pe`j' if recher==1 & newvar==`s', or capture noisily esttab using pe`i'_pe`j'_newvar`s'.csv, b ci noconstant nostar eform 154 forvalues j=`k'/20{ foreach s of numlist 1(1)13 { dis "pe`i' pe`j' lag`s'" capture noisily svy, subpop(if lagtime==`s' & recher==1): logit pe`i' pe`j', or capture noisily esttab using pe`i'_pe`j'_lag`s'wt.csv, b ci noconstant nostar eform plain Table 56(Cont’d). *Pe to Pe forvalues i=1/19{ local k=`i'+1 onecell label }}} gen nor=or replace nor=20 if nor>=20 & nub==20 twoway scatter nor firstpe if qt==1, mlabel(pelab) mlabsize(1.2) mlabposition (2) || rspike lb nub firstpe if qt==1 twoway scatter nor firstpe if qt==2, mlabel(pelab) mlabsize(1.2) mlabposition (2) || rspike lb nub firstpe if qt==2 twoway scatter nor firstpe if qt==3, mlabel(pelab) mlabsize(1.2) mlabposition (2) || rspike lb nub firstpe if qt==3 twoway scatter nor firstpe if qt==4, mlabel(pelab) mlabsize(1.2) mlabposition (2) || rspike lb nub firstpe if qt==4 //sensitivity analysis *Create non-overlapping lagtimes gen senlag=. replace senlag=1 if lagtime>=1 & lagtime<=3 replace senlag=2 if lagtime>=7 & lagtime<=8 replace senlag=3 if lagtime>=12 & lagtime<=13 *Check senlag (no overlap) tab lagtime senlag *Weighted PE-to-PE forvalues i=1/19{ local k=`i'+1 capture noisily svy, subpop(if recher==1 & senlag==`s'): logit pe`i' pe`j', or capture noisily esttab using pe`i'_pe`j'_senlag`s'.csv, b ci noconstant nostar eform plain onecell label }}} }}} gen nlb=lb replace nlb = round(nlb, .1) gen nub=ub replace nub = round(nub, .1) egen string ci = concat(nlb nub), punct(", ") export excel using "senlag.output", firstrow(variables) Code adapted from James C. Anthony NIDA T32 Trainee Research. forvalues j=`k'/20{ foreach s of numlist 1(1)3 { dis "pe`i' pe`j' senlag`s'" 155 Figure 15. Flow of Heroin Use Disorder Questionnaire Based on DSM-IV Criteria Data from United States National Surveys on Drug Use and Health, 2002-2016. Sequence follows choice/arrows (i.e., gated questions) and questions without choice/arrows followed by question in next row (i.e., asked for all participants who used heroin within 12 months of assessment). 156 Figure 15 (cont’d). Questionnaire used for heroin dependence case ascertainment in National Surveys on Drug Use and Health survey assessment, 2002-2016. Questions not followed by choice/arrows were asked for all those who used heroin within 12 months of survey assessment. To follow questionnaire sequence, follow choice/arrows and when not given choice/arrows then return to next row down. 157 Table 57. Meta-Analysis of Newly Incident Heroin Use to Dependence Probabilities. Data from United States National Surveys on Drug Use and Health, 2002-2016. NIHU (n) Transitioned to HUD (%) Meta Anlaysis Forest Plot 95% CI (13.8, 41.1) (7.9, 27.1) (15.4, 42.1) (16.3, 38.5) (27.8, 51.1) (23.9, 48.5) (24.2, 47.5) Population Projections Effective Samplea HUD Cases (n) HUD Cases (n) 38 56 41 59 65 56 63 26,000 104,000 17,000 114,000 26,000 98,000 39,000 150,000 63,000 162,000 57,000 163,000 52,000 149,000 25.0 15.2 26.7 25.9 38.8 35.2 35.0 Year Pairs 2002-2003 2004-2005 2006-2007 2008-2009 2010-2011 2012-2013 2015-2016 Meta.b NSDUH Restricted Use Dataset. (web Nov. 2018) aEffective n based on back-calculation method with standard errors, Vsevolozhskaya & Anthony, 2014 https://www.ncbi.nlm.nih.gov/pubmed/25175545 2014-2015 estimates not included due to covariance between year pairs. bMeta-analytic summary estimate: Log transformation and random effects estimator. Heterogeneity chi-squared = 9.82 (d.f. = 6) p = 0.133. (24.5, 36.7) 30.0 158 Table 58. Unweighted Odds Ratios of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 1: possible 0-90 days, assumed 30 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. 159 Table 59. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 0-90 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 1: possible 0-90 days, assumed 30 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 160 Table 60. Unweighted Odds Ratios of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 2: possible 1-120 days, assumed 60 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 161 Table 61. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 1-120 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 2: possible 1-120 days, assumed 60 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 162 Table 62. Unweighted Odds Ratios of Problem and Experience Pairs Within 30-150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 3: possible 30-150 days, assumed 90 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 163 Table 63. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 30-150 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 3: possible 30-150 days, assumed 90 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 164 Table 64. Unweighted Odds Ratios of Problem and Experience Pairs Within 60-180 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 4: possible 60-180 days, assumed 120 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 165 Table 65. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 60-120 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 4: possible 60-180 days, assumed 120 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 166 Table 66. Unweighted Odds Ratios of Problem and Experience Pairs Within 90-210 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 5: possible 90-210 days, assumed 150 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 167 Table 67. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 90-210 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 5: possible 90-210 days, assumed 150 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 168 Table 68. Unweighted Odds Ratios of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 6: possible 120-240, assumed 180 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 169 Table 69. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 120-240 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 6: possible 120-240, assumed 180 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 170 Table 70. Unweighted Odds Ratios of Problem and Experience Pairs Within 150-210 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 7: possible 150-270, assumed 210 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 171 Table 71. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 150-270 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 7: possible 150-270, assumed 210 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 172 Table 72. Unweighted Odds Ratios of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 8: possible 180-300, assumed 240 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 173 Table 73. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 180-300 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 8: possible 180-300, assumed 240 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 174 Table 74. Unweighted Odds Ratios of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 9: possible 210-330, assumed 270 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 175 Table 75. Unweighted Odds Ratios of Problem and Experience Pairs Within 210-330 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 9: possible 210-330, assumed 270 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 176 Table 76. Unweighted Odds Ratios of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 10: possible 240-360, assumed 300 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 177 Table 77. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 240-360 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 10: possible 240-360, assumed 300 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 178 Table 78. Unweighted Odds Ratios of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 11: possible 270-390, assumed 330 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 179 Table 79. Unweighted Odds Ratios of Problem and Experience Pairs Within 270-390 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 11: possible 270-390, assumed 330 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 180 Table 80. Unweighted Odds Ratios of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 12: possible 300-420, assumed 360 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 181 Table 81. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 300-420 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 12: possible 300-420, assumed 360 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 182 Table 82. Unweighted Odds Ratios of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 13: possible 330-450, assumed 390 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 183 Table 83. Unweighted Odds Ratio Confidence Intervals of Problem and Experience Pairs Within 330-450 Days of First Using Heroin. Data from United States National Surveys on Drug Use and Health, 2002-2016. NSDUH Downloadable Public Use Datasets. Lag-time interval 12: possible 330-450, assumed 390 days. Odds ratios produced from generalized linear model logistic regression, rounded to the tenths place. Analysis-weighted 95% confidence intervals use Taylor Series Linearization for calculus-based variance estimation. 184 APPENDIX C MANUSCRIPT 2 185 Table 84. MPlus Code to Evaluate Measurement Equivalence for Heroin Use Disorder Among Newly Incident Heroin Users. Variable: Names are age2 irsex year recher lagtime pe1 pe2 pe3 pe4 pe5 pe6 pe7 pe8 pe9 pe10 pe11 pe12 pe13 pe14 pe15 pe16 pe17 pe18 pe19 pe20 vestryr verepyr nanal_wt c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 opioid; Missing are all (-9999) ; Usevariables are c1-c10 opioid vestryr verepyr nanal_wt; Categorical are c1-c10; Grouping is opioid (1=twelve 2 = life 3 = never); Weight = nanal_wt; Stratification = vestryr; Cluster = verepyr; ANALYSIS: ESTIMATOR IS WLSMV; !DIFFTEST is deriv_.dat; Type = complex; MODEL: !Latent variable HUD - the * after y1 asks Mplus to estimate that loading !the (L1-L10) names each loading so that we can constrain them equal for women; HUD BY c1* c2 c3 c4 c5 c6 c7 c8 c9 c10 (L1-L10); HUD@1; !variance of latent variable = 1 [HUD@0]; !mean of latent variable = 0 {c1-c10@1}; !fixed for each item = 1 scale factor !thresholds [c1$1] (T1); [c2$1] (T2); [c3$1] (T3); [c4$1] (T4); [c5$1] (T5); [c6$1] (T6); [c7$1] (T7); [c8$1] (T8); [c9$1] (T9); [c10$1] (T10); Code citation: Dr. Ahnalee Brincks, 2018. Code adapted for weighted vs. unweighted analyses, comparisons across sex, and various model constraints. 186 Table 84 (cont’d). Model life: !Removing the (L1-L10) here frees the loadings to be different from males HUD BY c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 (L1-L10); !HUD*; !asks Mplus to estimate the variance of HUD [HUD@0]; !fixes mean of HUD = 0 {c1-c10@1}; !fixed for each item = 1 scale factor - required !thresholds [c1$1] (T1); [c2$1] (T2); [c3$1] (T3); [c4$1] (T4); [c5$1] (T5); [c6$1] (T6); [c7$1] (T7); [c8$1] (T8); [c9$1] (T9); [c10$1] (T10); Model twelve: !Removing the (L1-L10) here frees the loadings to be different from males HUD BY c1 c2 c3 c4 c5 c6 c7 c8 c9 c10 (L1-L10); !HUD*; !asks Mplus to estimate the variance of HUD [HUD@0]; !fixes mean of HUD = 0 {c1-c10@1}; !fixed for each item = 1 scale factor - required !thresholds [c1$1] (T1); [c2$1] (T2); [c3$1] (T3); [c4$1] (T4); [c5$1] (T5); [c6$1] (T6); [c7$1] (T7); [c8$1] (T8); [c9$1] (T9); [c10$1] (T10); Output: modindices(3.84); stdy; residual; Code citation: Dr. Ahnalee Brincks, 2018. Code adapted for weighted vs. unweighted analyses, comparisons across sex, and various model constraints. 187 APPENDIX D MANUSCRIPT 3 188 Table 85. Stata Code Used to Yield Case Crossover Discordant Pair Odds Ratios Displayed within Manuscript 3. set seed 618 *Outcome egen mystim = group(irstmyfu stimmfu) egen mystimnm = group(irstmnmyfu stmnmmfu) egen mycoc = group(ircocyfu cocmfu) *Exposure egen myher = group(irheryfu hermfu) *Time gen time=. replace time=mystim-myher gen time2=. replace time2=mystimnm-myher gen time3=. replace time3=mycoc-myher *2 Month Window gen cco=. replace cco=1 if (time<=2 & time>=1 | time2<=2 & time2>=1 | time3<=2 & time3>=1 ) replace cco=0 if (time<=4 & time>=3 | time2<=4 & time2>=3 | time3<=4 & time3>=3) replace cco=. if herflag==0 *Weights gen double vestryr=vestr*10000 gen verepyr=verep*10000+year gen nanal_wt=analwt_c/15 svyset verepyr [pweight=nanal_wt], strata(vestryr) singleunit(centered) *Cross Tabs *Unweighted Estimates foreach y of numlist 2002(1)2016 { * 0 case control 10 (case/control) *2002-2016 estimation… *Meta-Analyses replace luwest = log(uwest) replace lulb = log(uwlb) replace luub = log(uwub) metan luwest lulb luub if luwest>0, eform random lcols(year) //Weighted Estimates svy: tab cco foreach y of numlist 2002(1)2016 { * 0 case control 10 (case/control) *2002-2016 estimation… replace lwest = log(west) replace lwlb = log(wlb) replace lwub = log(wub) metan lwest lwlb lwub if lwest>0, eform random lcols(year) Code adapted from James C. 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