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THE INFLUENCE OF SYMPTOM SEVERITY ON MINOR
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A'ITENTION-DEFICIT/HYPERACTIVITY DISORDER

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TARA MICHELLE BRINKMAN

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5/08 KzlProjIAocauProsICIRC/DateDded

THE INFLUENCE OF SYMPTOM SEVERITY ON MINOR UNINENTIONAL
INJURIES AMONG CHILDREN WITH ATTENTION-DEFICIT/HYPERACTIVITY
DISORDER
By

Tara Michelle Brinkman

A DISSERTATION

Submitted to
Michigan State University
in partial fulﬁllment Of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
School Psychology

2009

ABSTRACT
THE INFLUENCE OF SYMPTOM SEVERITY ON MINOR UNINENTIONAL
INJURIES AMONG CHILDREN WITH ATTENTION-DEFICIT/HYPERACTIVITY
DISORDER
By
Tara Michelle Brinkman
The current study explored the understudied phenomenon of minor unintentional

injuries in a sample of children considered to be at-risk for such injuries. Using between
group analysis of covariance, results revealed no differences in minor unintentional injury
among children treated with extended release methylphenidate (N=9) and those treated
with extended release mixed amphetamine salts (N=10). For the entire sample (N=31),
linear regression procedures indicated that weekly measures of hyperactivity and
attention problems were associated with the number of injuries experienced during each
respective week of the study. However, results from hierarchical linear regression
revealed that symptoms associated with ADHD were not predictive of minor injury after
controlling for the presence of comorbid symptoms associated with conduct disorder.
Symptoms of conduct disorder accounted for nearly half of the variance in minor injuries
experienced by children with ADHD in this study. Finally, the relationships between
minor and severe injuries and other demographic variables were examined utilizing
logistic regression procedures. Results indicated that the number of parent-report minor
unintentional injuries experienced since birth, number of children living in the household.

and child age were each related to the likelihood that a child had experienced a medically

attended injury.

Cepyright by
TARA MICHELLE BRINKMAN
2009

ACKNOWEDGEMENTS

I would like to acknowledge several individuals who have been instrumental in
my development as a researcher and who have played an integral role in facilitating the
completion of my dissertation. First, I would like to thank my advisor and dissertation
committee chair, Dr. John Carlson, for the countless hours he devoted to assisting with
the conceptualization, development, and execution of this research project. I am grateful
for his guidance and unwavering support and encouragement. I also would like to thank
the members of my dissertation committee, Drs. Jean Baker, Sara Bolt, John Kosciulek,
and Jed Magen for their time, ﬂexibility, careful readings of my writing, and insightful
contributions to this project. Extreme gratitude is expressed to Dr. Richard Segool and
the staff at Pioneer Valley Pediatrics who diligently assisted with participant recruitment.
Appreciation is given to Kristyn Wong who served as a research assistant and contributed
to data collection and entry efforts. Finally, I would like to thank my colleagues, family,
and friends for their support and gracious tolerance of the demands associated with
graduate education/training and dissertation research.

This research project was partially funded by the Michigan State University
Graduate Student Dissertation Completion Fellowship and the School Psychology
Program Student Research Award. Additional support was provided by the Leadership
Training Grant Fellowship from the US. Department of Education, Ofﬁce of Special

Education Programs.

iv

TABLE OF CONTENTS

LIST OF TABLES ............................................................................................................ vii
CHAPTER 1

INTRODUCTION ............................................................................................................... 1

Current Study ........................................................................................................... 3

Signiﬁcance of Study ............................................................................................... 4
CHAPTER 2

LITERATURE REVIEW .................................................................................................... 6

Unintentional Injury ................................................................................................. 6

Nonfatal and Minor Injuries ......................................................................... 8

Injury Prevention ......................................................................................... 9

Risk Factors ............................................................................................... 1 1

Protective Factors ....................................................................................... 14

Attention-Deﬁcit/Hyperactivity Disorder .............................................................. 15

Unintentional Injury ................................................................................... 16

Driving Safety ............................................................................................ 20

Pedestrian Safety ........................................................................................ 23

Injury Risk ................................................................................................. 23

Stimulant Medication and Unintentional Injury .................................................... 27

Current Study ......................................................................................................... 34

Research Questions ................................................................................................ 35
CHAPTER 3

METHOD .......................................................................................................................... 37

Participants ............................................................................................................. 37

Materials ................................................................................................................ 38

Demographic Information Questionnaire .................................................. 38

Vanderbilt ADHD Parent Rating Scale ..................................................... 38

Child Behavior Checklist — Parent ............................................................. 39

Behavior Assessment System for Children — Monitor .............................. 40

Minor Injury Severity Scale ....................................................................... 40

Injury History Questionnaire ..................................................................... 41

Procedures .............................................................................................................. 41

Research Design & Data Analysis ......................................................................... 42
CHAPTER 4

RESULTS .......................................................................................................................... 46

Descriptive Statistics .............................................................................................. 46

Clinical Symptoms ................................................................................................. 46

Unintentional Injuries ............................................................................................ 47

Relationships among Clinical Symptoms and Unintentional Injuries ................... 47

Research Question 1: Medication Treatment ......................................................... 49

Research Question 2: ADHD Symptom Severity .................................................. 51

Research Question 3: Comorbid Symptoms .......................................................... 54
Research Question 4: Unintentional Injuries ......................................................... 55
CHAPTER 5
DISCUSSION .................................................................................................................... 58
Unintentional Injuries ............................................................................................ 58
Medication Treatment ............................................................................................ 6O
ADHD Symptomatology and Unintentional Injuries ............................................ 63
Comorbid Symptomatology and Unintentional Injuries ........................................ 66
Medically Attended Unintentional Injuries ........................................................... 68
Conclusions ............................................................................................................ 70
Clinical Implications .............................................................................................. 72
Future Research ..................................................................................................... 74
Limitations ............................................................................................................. 76
APPENDICIES .................................................................................................................. 78
Appendix A: Table 1. Demographic Characteristics ............................................. 79
Appendix B: Table 2. Medication Treatment ........................................................ 80
Appendix C: Table 3. Clinical Symptoms: CBCL ................................................. 81
Appendix D: Table 4. Clinical Symptoms: BASC-Monitor .................................. 82
Appendix B: Table 5. Correlations among behavioral ratings of ADHD and
comorbid symptoms ...................................................................................... 83
Appendix F: Table 6. Relationship between weekly ADHD symptom
severity and unintentional injuries: Regression models ................................ 84
Appendix G: Table 7. Correlation matrix: parent-reported injuries ...................... 85
Appendix H: Table 8. Logistic regression predicting the likelihood of a
medically attended injury since birth ........................................................... 86
REFERENCES .................................................................................................................. 87

vi

LIST OF TABLES

Table 1. Demographic Characteristics ............................................................................... 79
Table 2. Medication Treatment .......................................................................................... 80
Table 3. Clinical Symptoms: CBCL .................................................................................. 81
Table 4. Clinical Symptoms: BASC-Monitor .................................................................... 82
Table 5. Correlations among behavioral ratings of ADHD and comorbid symptoms ....... 83
Table 6. Relationship between weekly ADHD symptom severity and unintentional
injuries: Regression models ................................................................................. 84
Table 7. Correlation matrix: parent-reported injuries ........................................................ 85

Table 8. Logistic regression predicting the likelihood of a medically attended injury
since birth ............................................................................................................. 86

vii

Chapter 1
INTRODUCTION

Unintentional injury is the leading cause of death and disability for children and
adolescents in the United States (Centers for Disease Control and Prevention, 2004). In
2002, over 1 1,000 children aged 1 to 18 died from unintentional injuries (Anderson &
Smith, 2005). This resulted in approximately 220 deaths per week or 31 deaths every
day. Fatal and nonfatal unintentional injuries impart an economic cost of billions of
dollars each year (Danesco, Miller, & Spicer, 2000). As such, these injuries pose a
signiﬁcant public health concern and the government has identified the reduction of
injury as a major focus within Healthy People 2010 (United States Department of Health
and Human Services, 2005).

The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) has
identiﬁed accidental injury as an associated feature of attention—deﬁcit/hyperactivity
disorder (ADHD; APA, 2000). Additionally, research suggests that children with ADHD
are at increased risk for incurring unintentional injuries (DiScala, Lescohier, Barthel, &
Li, 1998; Schwebel, Speltz, Jones, & Bardina, 2002). These injuries result in greater
health care service utilization and costs for children with ADHD relative to their typically
developing peers (Leibson, Katusic, Barbaresi, Ransom, & O’Brien, 2001; Ray et al.,
2006). Despite the recognition of the need for unique injury prevention efforts targeted
toward children with ADHD (Farmer & Peterson, 1995), research focusing on such
efforts is virtually nonexistent.

Research and theory lend preliminary support for the role of stimulant medication

as a possible mechanism by which to moderate rates of unintentional injury among

children with ADHD (Lage & Hwang, 2004; Rapport, Chung, Shore, & Isaacs, 2001).
Stimulant medication is the most commonly utilized treatment for ADHD and following
such treatment the majority of children with ADHD evidence a reduction in symptoms
associated with the disorder (Pelham et a1, 2000; MTA, 1999). A conceptual model of
ADHD also suggests that stimulant medication treatment which impacts the core features
of ADHD (i.e., inattention, hyperactivity-impulsivity) should subsequently have a trickle
down effect on the associated features of the disorder, such as unintentional injury
(Rapport et al., 2001). It is clear, however, that the treatment effects of stimulant
medication are generally not great enough to normalize behavior (Pelham et al., 2000).

Limited research has directly explored the impact of stimulant use on rates of
unintentional injury among children with ADHD. Preliminary data suggest that stimulant
medication treatment may mitigate the risk for medically attended unintentional injuries
among children with ADHD. For example, following stimulant treatment children with
ADHD had signiﬁcantly fewer emergency department visits and costs when compared to
periods off stimulants (Leibson et al., 2006). Moreover, children treated with extended
release stimulant medication were less likely to experience a medically attended accident
or injury compared to those treated with immediate release stimulant medication (Lage &
Hwang, 2004).

No research has examined the relationship between stimulant medication
treatment and minor unintentional injuries among children with ADHD. Several
researchers have articulated the importance of studying minor unintentional injuries as a
proxy for more serious injury (Morrongiello, Ondejko, & Littlejohn, 2004; Peterson,

Brown, Bartelstone, & Kern, 1996). The prospective study of serious injuries is difﬁcult

and would require extremely large numbers of participants. Minor unintentional injuries;
however, are relatively common and have been reliably measured and systematically
studied (Peterson, Saldana, & Heiblum, 1996).

Research has explored the role of hyperactive and inattentive behaviors as
potential mediating/moderating variables for injury risk among children (Schwebel et al.,
2004; Spinks, Nagle, Macpherson, Bain, & McClure, 2008). While there is substantial
evidence to suggest that such behavior patterns are related to increased injury risk among
typically developing children (Schwebel & Barton, 2006), data regarding the relationship
between the symptoms of hyperactivity and inattention and injury risk among children
with a diagnosis of ADHD have been mixed (Bryne et al., 2003; DuPaul et al., 2001;
Pastor & Reuben, 2001 ). Yet, researchers in the area of pediatric unintentional injury
have hypothesized that children with externalizing behavior disorders are at increased
risk of injury not because of hyperactive or inattentive behaviors, but instead because of
their oppositional, deﬁant and disruptive behavior (Davidson et al., 1988; Schwebel et al.,
2007). Limited research; however, has explored the relationship between the core
symptoms of ADHD in addition to the symptoms of comorbid externalizing behavior
disorders on unintentional injury risk among children with a diagnosis of ADHD.
Current Study

The current study will investigate the relationship between psychostimulant
medication treatment and minor unintentional injuries among children with ADHD.
Speciﬁcally, the study will examine the inﬂuence of two different psychostimulant
medication treatments commonly prescribed to target the core symptoms of hyperactivity

and inattention in children with ADHD to determine the differential impact of such

treatment patterns on unintentional injury. Unintentional injury is the leading cause of
morbidity and mortality for children and adolescents, and children with ADHD have been
identiﬁed as being at increased risk for incurring unintentional injuries. Stimulant
medication treatment has consistently been demonstrated to effectively reduce the core
symptoms of ADHD, such as hyperactivity and inattention, yet limited research has
explored the impact of stimulant medication treatment on unintentional injury. The
primary research questions center on investigating (a) the relationship between
psychostimulant medication treatments and minor unintentional injuries among children
with ADHD, (b) the risk for unintentional injury based on severity of ADHD symptoms
and the presence of comorbid symptoms, and (c) the relationship between minor and
severe injury among children with ADHD.
' Significance of Study

This study will explore an understudied phenomenon of minor unintentional
injuries in a population that is considered to be at-risk for such injuries. This project will
contribute to the existing knowledge base through an exploration of the relationship
between psychopharrnacological treatments and rates of minor unintentional injury
among children with ADHD. In addition, weekly monitoring of hyperactivity and
inattention will permit for an examination of the extent to which symptom severity is
predictive of injury. Assessment of symptoms of comorbid disorders will allow for an
understanding of the impact of associated disruptive behaviors on injury risk. Given the
focus on unintentional injury, ADHD, and medication treatment, this project has
signiﬁcant public health implications. The prevalence of ADHD suggests that this

disorder impacts 3 large number of children and families. Further, the economic burden

of managing the medical needs of these children is substantially greater than for typically
developing children. Finally, as the leading cause of disability and death in children,
unintentional injuries pose a major public health concern and warrant scientiﬁc inquiry.
Understanding the impact of symptom severity and medication treatment on rates of
unintentional injury among children with ADHD may have large-scale implications

related to injury prevention efforts and costs associated with injury treatment.

Chapter 2
LITERATURE REVIEW

Unintentional injuries are the leading cause of morbidity and mortality for
children and adolescents in the United States (Centers for Disease Control and
Prevention, 2004; Guyer et al., 1999). Research has indicated that children with ADHD
are at increased risk for incurring such injuries (DiScala et al., 1998; Schwebel et al.,
2002). A conceptual model of ADHD along with preliminary research lend support for
the role of stimulant medication as a means by which to mitigate injury risk within this
population (Lage & Hwang, 2004; Rapport et al., 2001); however, additional research
investigating the extent to which stimulant medication might serve as a protective factor
is needed. This literature review will begin by deﬁning unintentional injury and
highlighting the prevalence and signiﬁcance of this phenomenon. This will be followed
by a brief review of traditional approaches toward injury prevention. Risk and protective
factors associated with childhood unintentional injury will be reviewed. The second part
of this review will provide a critical analysis of the literature focusing on unintentional
injuries among children with ADHD. Finally, this review will present the theory and
research reported within the literature to date regarding the use of stimulant medication in
relation to unintentional injuries. The purpose of the current study is described and
research questions are presented.
Unintentional Injury

Injury has been deﬁned as bodily damage resulting from exposure to physical or
chemical agents (Roberts, Brown, Boles, & Mashunkashey, 2004; Roberts, Brown,

Boles, Mashunkashey, & Mayes, 2003). The most common unintentional injuries among

children and adolescents result from motor vehicle crashes, ﬁres, falls, drownings,
bicycle crashes, suffocations, and poisonings (Centers for Disease Control and
Prevention, 2004). Outside of the scientiﬁc community, a term frequently utilized to
describe unintentional injury is “accident.” However, utilization of the term
unintentional rather than accidental reﬂects a change in the understanding of injury.
Unintentional injury was traditionally conceptualized as a result of carelessness or chance
(Kronenfeld & Glik, 1995). Given this understanding and the presumed unpredictability
of injuries, they were largely viewed as unpreventable and described as accidents.
However, injury is now recognized as an event that can be subjected to scientiﬁc study
and whose occurrence can be understood in a manner similar to that of other diseases
(Roberts et al., 2004). Research has identiﬁed speciﬁc factors that place children at
increased risk for injury. For example, boys are consistently reported to experience more
injuries than are girls (Bijur, Golding, Haslum, & Kurzon, 1988; Bradbury, Janike, Riley,
& Finney; 1999), and limited parental supervision is associated with increased injury risk
among toddlers (Morrongiello, Corbett, McCourt, & Johnston, 2006). Importantly,
unintentional injury is now widely recognized as an event that can be prevented.
Advances in medical knowledge and technologies have resulted in the reduction
of morbidity and mortality rates by infectious diseases. This has led to emergence of
unintentional injury as the leading cause of death and disability for children and
adolescents in the United States (Kronenfeld & Glik, 1995). In 2002, unintentional injury
accounted for nearly 40% of deaths among children ages 5-14 (Centers for Disease
Control and Prevention, 2004). Among this age range, unintentional injury accounted for

more than twice as many deaths as the second leading cause of death, malignant

neoplasms (Centers for Disease Control and Prevention, 2004). The leading cause of
death by unintentional injury for children, adolescents, and adults is motor vehicle trafﬁc
incidents (Centers for Disease Control and Prevention, 2004).

Nonfatal and Minor Injuries. As nonfatal unintentional injuries have the potential
to be extremely serious and occur more frequently than fatal injuries such events also
warrant attention. For each injury related childhood death, there are approximately 18
hospitalizations, 233 emergency department visits, and a much larger number of home-
treated injuries (Grossman, 2000). The leading cause of hospital attended nonfatal injury
is unintentional falls (Centers for Disease Control and Prevention, 2004). Minor injuries
are typically conceptualized as events which do not require medical attention or
treatment. Several researchers have identiﬁed the utility of studying minor unintentional
injury as a proxy for more serious injury especially given their potential for serious injury
(Damashek & Peterson, 2002; Morrongiello et al., 2004; Peterson et al., 1996). As Pless,
Taylor, and Arsenault (1995) articulated, prospective studies are almost impossible when
studying serious unintentional injuries. Over 35,000 children would have to be followed
for 1 year to yield 100 serious injuries (Pless, Taylor, & Arsenault, 1995). Medically
attended injuries are low-base rate events and it is unclear as to whether these injuries are
consistently more serious than non-medically attended injuries as the decision to seek
medical care may be related to factors other than actual injury severity (Peterson, DiLillo,
Lewis, & Sher, 2002). Minor unintentional injuries are relatively common and have been
reliably measured and systematically studied (Peterson et al., 1996). The relationship
between minor and more severe injuries also has been reported within the literature.

Children who experience multiple minor injuries have been reported to be more likely to

sustain more severe injuries (Alkon et al., 1994) and a signiﬁcant positive correlation (r =
.67) has been reported between serious injuries and later occurring minor injuries among
toddlers (Morrongiello et al., 2004). Moreover, Jaquess and Finney (1994) found that
children, aged 3 to 11, who received medical attention for an injury were more likely to
have home treated injuries in the subsequent year.

When considered together, fatal and nonfatal unintentional injuries impart an
estimated economic cost of $347 billion each year (Danesco et al., 2000). This estimate
includes injury treatment, future lost wages, and diminished quality of life. Additionally,
each year there are approximately 7 million emergency department visits and 10 million
primary care visits related to injury treatment (Ballesteros, Schneiber, Gilchrist,
Holmgreen, & Annest, 2003). Given the scope of the problem comprehensive approaches
toward injury prevention and a thorough understanding of factors that place children at
risk and protect them from incurring injuries are critical.

Injury Prevention. Injury prevention efforts are typically conceptualized as either
passive or active. Passive prevention requires no action by individuals whereas active
prevention requires the individual to engage in a speciﬁed behavior in order to receive the
preventive beneﬁt (Roberts et al., 2004). Passive prevention efforts often consist of
changes to existing products which stem from legal mandates or structural changes to the
environment (Damashek & Peterson, 2002; Roberts et al., 2004). The installation of
airbags in cars is an example of passive prevention. In some instances passive prevention
efforts are not entirely passive and require individual action. For example, the passage of
a law requiring medicines to be packaged in childproof containers is passive prevention,

yet it necessitates that adults replace the caps correctly after use, thus requiring some

action (Roberts et al., 2004). Most injury prevention advocates encourage passive
prevention efforts such that the preventive beneﬁts are shared by everyone regardless of
individual action or inaction (Roberts et al., 2004). Active prevention can be illustrated
by car seat belts or bicycle helmets. While these products are designed to prevent
automobile and bicycle related injuries, individuals are required to engage in some
behavioral action to attain preventive beneﬁts.

Five levels of injury prevention and intervention have been articulated by
Damashek and Peterson (2002). National and state level initiatives consist of media
campaigns to educate caregivers about safety or federal laws that mandate safety changes
in products or behavior. For example, some states have legal mandates regarding the use
of bicycle helmets. A second level of intervention occurs at the community level.
Interventions at this level include local laws or community injury prevention programs.

F amily-level initiatives may focus on individual families or groups of families. These
interventions may center on educating parents who in turn teach their children safety
skills in the home. Finally, caregiver and child level initiatives are typically in the form
of education or behavioral training. Behavioral interventions may focus on rewarding
children for safety belt use while educational practices may involve health practitioners
distributing pamphlets to parents (Damashek & Peterson, 2002).

The use of behavioral rewards and educational training are among the most
common components of childhood injury prevention programs described in the literature.
While a detailed discussion of individual prevention programs is beyond the scope of this
literature review, such approaches have been effectively implemented to increase the use

of seat belts, safety seats, and bicycle helmets (Hall, Cross, Howat, Stevenson, & Shaw,

lO

2004; Khambalia, MacArthur, & Parkin, 2005; Roberts, Alexander, & Knapp, 1990;
Roberts & Fanurik, 1986). These programs also have yielded increases in safe behavior
on playgrounds and improvements in teacher and child knowledge related to safe
behavior (Heck, Collins, & Peterson, 2001; Schwebel, Summerlin, Bounds, &
Morrongiello, 2006). It is more difﬁcult; however, to determine the extent to which these
injury prevention programs actually reduce rates of unintentional injury. Further, it is
unclear as to whether these programs are sufﬁcient to meet the needs of children who
may be at increased risk for experiencing unintentional injuries.

Risk Factors. Research has identiﬁed several factors that appear to consistently
place children at increased risk for incurring unintentional injuries. These risk factors are
typically conceptualized as characteristics of the child, primary caregiver, or
environment. One of the most robust ﬁndings within the unintentional injury literature
indicates that males are at signiﬁcantly increased risk for experiencing injuries than are
females (Bijur et al., 1988; Danesco et al., 2000; Hambidge, Davidson, Gonzales, &
Steiner, 2002; Scheit et al., 1995). A review of 8 years of National Health Survey data
for individuals under the age of 21 revealed that males were signiﬁcantly more likely to
experience medically attended nonfatal and fatal injuries than were females. Moreover,
the fatal injury rate for males was more than twice that for females (Danesco et al., 2000).
Among children and adolescents, males also have been reported to have more nonfatal
injury-related primary care visits than females (Hambidge et al., 2002).

With respect to race, injury risk appears to vary with respect to injury severity.
Utilizing data from a national sample of over 3,000 children, Danesco and colleagues

(1998) reported that white children had higher nonfatal injury rates than non-white

ll

children while black children had higher rates of fatal injury compared to white children
(Danesco et al., 1998). Partial support for this ﬁnding emerged from a recent study by
Dal Santo, Goodman, Glick, and Jackson (2004) who reported that white children were at
almost three times the risk of experiencing a nonfatal injury than were non-white
preschoolers. Others have also reported that non-white preschoolers are at greater risk
for incurring fatal injuries than are white preschoolers (Kennedy & Lipsitt, 1998;
Morrongiello & Rennie, 1998).

Among typically deveIOping children, indices of vigilance performance have been
associated with unintentional injuries among young children. Bennett-Murphy, Murphy,
and Rose (2001) reported that vigilance indicators of response bias and perceptual
sensitivity were predictive of parent-reported minor unintentional injuries among
preschool-aged children (n = 28), with these two variables accounting for nearly half of
the variability in unintentional injuries. These ﬁndings suggest that children who were
less vigilant were injured more often than those who maintained high vigilance. In a
case-control study of injured children, aged 5-15, Pless and colleagues (1995) compared
286 children who had received medical attention for involvement in trafﬁc accidents as a
bicyclist or pedestrian. Children in the control group (n = 562) experienced injuries
where their behavior was not a contributing factor to the injury, for example, as a
passenger in a car. The study found that children who had been injured in part due to
their own behavior made more errors of omission and commission on a continuous
performance task of attention, suggesting that these children were less attentive and more

impulsive than controls, respectively. Additionally, children whose behavior contributed

12

to their injury had greater hyperactivity scores as rated by parent and teacher on a
standardized behavior rating scale (Pless et al., 1995).

Several early studies reported that hyperactivity and aggressive behavior were
important risk factors for childhood injury (Bijur, Stewart, Brown, & Butler, 1986;
Langley, McGee, Silva, & Williams, 1983; Meyer, Roelofs, Bluestone, & Redmond,
1963). A critical review of this literature; however, revealed several methodological
limitations. Davidson (1987) indicated that these studies utilized poor measures of
behavior, lacked appropriate control groups, and were largely retrospective in nature.
Results from those studies which prospectively measured injury among children with
behavioral difﬁculties revealed an association between antisocial behavior (e. g.,
aggression, management difﬁculties) and injury. The relationship between hyperactivity
and injury was reported as limited.

Following this review, Davidson and colleagues further reported that children
with discipline and conduct problems were at increased risk for medically attended
injuries while hyperactivity and lack of concentration were not associated with injury
(Davidson, Hughes, & O’Connor, 1988; Davidson, Taylor, Sandberg, & Thorley, 1992).
More recently, utilizing both retrospective and prospective design methodologies,
Schwebel and colleagues (2004) found that hyperactivity was a strong predictor for
parent-reported medically attended injuries among 5-year-olds and children from 3 to 36
months of age. Among the 5-year-olds (n > 10,000) studied retrospectively, the odds
ratio for hyperactivity was 28.39, suggesting that hyperactive children were over 2,800%
more likely to experience an injury than their nonhyperactive peers (Schwebel et al.,

2004). Additionally, Spinks and colleagues (2008) investigated the association between

13

hyperactivity, aggression, and childhood injury among children aged 5 to 12 years. Using
select items from the Child Behavior Checklist and parent-reported injuries, their results
indicated that children with elevated hyperactivity scores had an increased risk for all
injuries including medically treated injuries. No signiﬁcant association between
aggression and childhood injury was reported.

In considering the ﬁndings of the aforementioned studies, it is important to note
that the results do not generalize to children with diagnosed externalizing behavior
disorders. These studies only examined injuries among children who were identiﬁed as
having externalizing behavior difﬁculties, such as hyperactivity or oppositionality, oﬁen
at subclinical levels. As such, it is unclear if these patterns of risk would hold true for
children with actual clinical diagnoses. However, there does appear to be a clinical
perception that children with externalizing behavior difﬁculties are especially liable for
incurring injuries (Byrne, Bawden, Beattie, & Wolfe, 2003). Given the core features of
these disorders (e. g., impulsivity, inattention, oppositionality) this association is
intuitively appealing. One might expect that a child who is not attending to his
environment or who deﬁes safety instructions from an adult may be more prone to
experience an injury. As will be reviewed later, empirical data regarding the relationship
between these clinical disorders, their core behavioral features, and unintentional injury
have been somewhat mixed.

Protective Factors. The literature within the child injury ﬁeld is replete with
studies focusing on injury risk, yet limited attention has been paid to factors that may
serve to protect children from injury (Schwebel, Brezausek, Ramey, & Ramey, 2004).

Models of developmental psychopathology support the need to identify both risk and

14

protective factors to better understand the development of psychological disorders and
the same theoretical approach may serve to enhance our understanding of childhood
unintentional injury. As described earlier, Schwebel and colleagues (2004) reported that
hyperactivity was a strong predictor for early childhood injury. In this same study,
interactions between child and parent characteristics served to protect children from
injury. Speciﬁcally, among 5-year-old children, those with hyperactive behavior patterns
whose parents reported having adequate time resources experienced fewer injuries than
children whose parents did not report adequate time resources. This indicates that
children without hyperactive behaviors were at increased risk for injury, relative to
hyperactive children, if their parents did not have adequate time to spend with them. This
ﬁnding suggests that aspect of parenting, such as having sufﬁcient time to spend with
children, might mitigate injury risk among children who are generally believed to be at
increased risk for injury (Schwebel et al., 2004). In order to fully understand injury risk
for children, a thorough conceptualization of both risk and protective factors is necessary
and additional research exploring how these factors might mitigate injury risk is
warranted.
Attention—Deﬁcit/Hyperactivity Disorder

Attention-deﬁcit/hyperactivity disorder (ADHD) is one of three externalizing
behavior disorders recognized by the American Psychiatric Association (APA; American
Psychiatric Association, 2000). This disorder is associated with signiﬁcant impairments
in inattention and/or hyperactivity-impulsivity as well as difﬁculties related to academics,
peer relations, and psychological comorbidities (Barkley, 2003). Prevalence rates of

ADHD are estimated between 3 and 7 percent among school-aged children (APA, 2000).

15

The male-to-female ratio is estimated to be between 2:1 to 9:1 depending on the subtype
and setting (APA, 2000). Nearly half of children with ADHD also present with comorbid
Oppositional Deﬁant Disorder (ODD) or Conduct Disorder (CD) (APA, 2000). A
signiﬁcant portion of children identiﬁed as having ADHD continue to meet diagnostic
criteria for the disorder in adolescence and adulthood (Barkley, 2003).

Unintentional Injury. The Diagnostic and Statistical Manual of Mental Disorders
(DSM-lV—TR) identiﬁes accidental injury as an associated feature of attention-
deﬁcit/hyperactivity disorder (APA, 2000). Early research reported that children with
attention-deﬁcit disorder (ADD; as identiﬁed within the DSM-III) were more likely to
experience physical injuries necessitating sutures, hospitalizations or medical procedures
than were controls (Jensen, Shervette, Xenakis, & Bain, 1988). Children with ADD were
also reported as more likely to experience burns (Szatmari, Offord, & Boyle, 1989), bone
fractures (Szatmari et al., 1989), and unintentional poisonings (Stewart, Thach, &
Friedin, 1970) or ingestion of poisonous substances (Jensen et al., 1988). As reported by
Barkley (2003), data from Shelton and colleagues (1998) indicated that more than four
times as many children with ADHD as control children were reported to experience an
accident related to their impulsive behavior (Shelton et al., 1998).

Several recent studies have systematically explored the relationship between
unintentional injury and children with ADHD. DiScala and colleagues (1998) examined
differences in hospital admitted injuries to children aged 5 to 14 identiﬁed with either
preinjury ADHD or no preinjury conditions. They reported that children with ADHD
were more likely to be injured as pedestrians, bicyclists, and to sustain more head injuries

and injuries to multiple body regions relative to children with no preinjury condition.

16

Further, children with preinjury ADHD were more severely injured and were more
frequently admitted to the intensive care unit (DiScala et al., 1998). Others also have
reported that children with premorbid ADHD are disproportionately represented among
children with closed head injuries (Gerring et al., 1998). The premorbid prevalence of
ADHD among children aged 4 to 19 years with moderate to severe closed head injuries
was reported at .20 compared with a prevalence of .045 in a reference population. These
authors further reported that 77% of children with premorbid ADHD were not receiving
mental health treatment at the time of their injury (Gern'ng et al., 1998).

While these ﬁndings appear to support an association between ADHD and injury,
speciﬁcally head injury, such a conclusion is tenuous for several reasons. First, both of
these studies identiﬁed the presence of premorbid ADHD through interviews with parents
and children following the occurrence of an injury. Such retrospective reports of
behavior may introduce bias in that the perception of a child’s behavior can be inﬂuenced
by an injury to that child (Davidson, 1987). Head injuries also have the potential to alter
a child’s behavior and thus post-injury behavior could inﬂuence ratings of premorbid
behavior (Davidson, 1987). Additionally, these studies did not control for comorbid
psychiatric conditions such as ODD or CD. As such, the inﬂuence of these comorbid
conditions is unclear as is the heterogeneity of the samples employed.

Two recent studies examined the speciﬁc relationship between ADHD and burn
injuries (Mangus, Bergman, Zieger, & Coleman, 2004; Thomas, Ayoub, Rosenberg,
Robert, & Meyer, 2004). Both studies utilized retrospective chart reviews to assess
differences in burn rates among children with and without ADHD. While neither study

found a higher prevalence of burn injuries among children and adolescents with ADHD,

l7

some differences between the groups did emerge. Mangus and colleagues (2004)
reported that children with ADHD were more likely to experience a thermal rather than a
ﬂame burn, had more extensive burn injuries, and were less likely to be discharged home
than children without ADHD. Thomas and colleagues (2004) reported that impulsive
behavior contributed to the burn injury in approximately half of the 21 cases of children
with ADHD. Additionally, in 9 of these 21 cases, children with ADHD were not taking
their prescribed stimulant medication on the day of the injury (Thomas et al., 2004).
Injury episodes are important reasons that parents seek medical care for their
children in emergency departments, outpatient clinics, and primary care ofﬁces. As such,
patterns of health care service utilization among children with ADHD can provide
important information regarding the association between these disorders and
unintentional injury. Pastor and Reuben (2006) examined the rates of medically attended
nonfatal injuries among children with and without ADHD. They reported that children
and adolescents aged 6 through 17 years with ADHD were more than twice as likely to
experience a medically attended injury when compared to children without ADHD.
Annual injury rates for children with ADHD were 204 episodes per 1000 children
compared with 115 episodes per 1000 among children without ADHD. Individuals with
ADHD also have been reported to be 1.7 times more likely to have an accident claim than
controls (Swensen et al., 2004). The presence of one or more psychiatric comorbidities
increased the likelihood of an accident claim among adolescents (Swensen et al., 2004).
Additionally, a population-based cohort study utilizing school and medical records
revealed that children with ADHD had more hospital inpatient, hospital outpatient, and

emergency department admissions than children without ADHD (Leibson et al., 2001).

18

Children with ADHD also had medical costs that were more than double those of
children without ADHD (Leibson etal., 2001). Taken together these ﬁndings provide
additional support for the association between ADHD and increased risk for injury and
associated medical service utilization. However, it is important to note that a clinical
diagnosis of ADHD was not veriﬁed and the possible confounding inﬂuence of comorbid
psychiatric conditions was not explored in all of these studies.

Research also has explored the relationship between preschoolers with ADHD
and unintentional injury (Byrne et al., 2003; DuPaul, McGoey, Eckert, & VanBrakle,
2001; Lahey et al., 1998). In a study designed to examine the validity of DSM-IV
ADHD diagnostic criteria, Lahey and colleagues (1998) reported that children aged 4
through 6 years who met criteria for ADHD Hyperactive-Impulsive type (ADHD-HI)
were signiﬁcantly more likely than controls to have experienced an unintentional injury.
When children with comorbid ODD and CD were dropped from the statistical analyses,
children who met criteria for ADHD Combined type (ADHD-C) also had signiﬁcantly
more parent reported injuries than control children. No differences in injury rates were
observed between children with ADHD Inattentive type (ADHD-PI) and controls.
Findings from subsequent studies, however, have not supported these results. While
Byrne et a1. (2003) found that preschoolers with ADHD were reported by their parents to
engage in more behaviors that placed them at-risk for injury, these children did not
actually sustain more injuries than control children. Additionally, DuPaul and colleagues
(2001) found no differences in the number injuries between 3 through 5 year old children

with ADHD and normal controls.

19

Possible rationale for these discrepant ﬁndings center on how injury was
measured or diagnostic process. For example, while the later studies reviewed children’s
medical records to assess injury, it is unclear if Lahey and colleagues (1998)
supplemented parent reported injuries with a review of medical charts. Further, it is
unclear whether Lahey et al. (1998) measured minor home-treated or medically attended
injuries. In contrast to minor injuries, medically attended injuries are low base rate
events and young children may not have experienced enough of these injuries to result in
statistically signiﬁcant group differences. Small sample sizes also may have limited the
power to detect statistical signiﬁcance in the studies conducted by DuPaul et al. (2001)
and Byrne et al. (2003). Speciﬁcally, DuPaul and colleagues (2001) reported that injury
data were only available for approximately half of their sample (n = 47). While the group
differences did not reach statistical signiﬁcance the effect size for number of injuries was
rather large (1.20), thus indicating practical signiﬁcance (DuPaul et al., 2001).

Driving Safety. Given that motor vehicle collisions account for a large number of
unintentional injuries among children and adolescents, the relationship between ADHD
and driving related outcomes has been investigated. In a series of longitudinal studies,
adolescents and young adults with ADHD were reported to be 2 to 4 times more likely to
experience a motor vehicle collision and more than 3 times more likely to incur
associated injuries. These individuals were also more likely to be at-fault in motor
vehicle crashes than were individuals without ADHD (Barkley, Guevremont,
Anastopoulos, DuPaul, & Shelton, 1993; Barkley, Murphy, & Kwansik, 1996).
Additionally, adolescents and young adults with ADHD were more likely to have

received trafﬁc citations, especially for speeding, as well as to have their licenses

20

suspended. Teenagers with greater comorbid ODD and CD symptoms were found to be
at the greatest risk for negative driving outcomes (Barkley et al., 1993). Speciﬁcally,
symptoms associated with ODD and CD accounted for a signiﬁcant amount of variance
in all of the negative driving outcomes whereas symptoms exclusively associated with
ADHD did not. As such, Barkley and colleagues (1993) concluded that negative driving
outcomes may be a function of the degree of antisocial symptoms rather than the degree
of ADHD.

Research has further reported that individuals with ADHD perform more poorly
on computer-simulated driving tests compared to those without ADHD (Barkley et al.,
1996). During these driving tasks, adolescents and young adults with ADHD
experienced more crashes, scrapes, and erratic steering than the control group. Yet, no
group differences were reported with respect to driving knowledge (Barkley et al., 1996).
An important consideration of these early studies is that they did not examine the impact
of comorbid substance abuse disorder. Research indicates that adolescents and young
adults with ADHD who currently exhibit or have previously experienced coexisting
conduct problems are at increased risk for substance abuse difﬁculties compared to those
without the disorder (Barkely, 2003). The presence of such difﬁculties may inﬂuence
driving outcomes for this population. In one study, twenty percent of individuals with
ADHD had received a trafﬁc citation for drunk driving compared to 0% of those in the
control group (Barkley et al., 1996). While this ﬁnding did not reach statistical
signiﬁcance its clinical importance cannot be ignored.

In a longitudinal study, Nada-Raja and colleagues (1997) further explored the

extent to which inattentive and hyperactive symptoms of ADHD at age 15 were

21

associated with driving offenses among adolescents, aged 15 to 18. They reported that
driving offenses among males were associated with signiﬁcant ADHD symptomatology
or the presence of conduct disorder. Signiﬁcant ADHD symptomatology was deﬁned as
a score of at least 1.5 standard deviation above the mean on the DSM-III total ADHD
symptom scale. Males with ADHD were signiﬁcantly more likely than males with other
disorders or no disorder to drive a car within 2 hours of consuming alcohol, although a
higher proportion of males with conduct disorder received actual alcohol related trafﬁc
citations. Among females, driving offenses and motor vehicle crashes were more
frequently noted among those who scored high on the ADHD symptom scale rather than
those who met criteria for conduct or oppositional disorder. While the authors concluded
that risky driving behavior cannot be explained entirely by the presence of ADHD (Nada-
Raja et al., 1997), these ﬁndings do support the importance of assessing symptom
severity when studying the relationship between ADHD and injury risk.

Woodward, Fergusson, and Horwood (2000) conducted a longitudinal study to
examine the associations between attentional difﬁculties at age 13 and driving outcomes
at age 21. They reported that an increased level of attention problems in adolescence
resulted in a subsequent increased risk for motor vehicle collisions involving injury,
drunk driving, and illegal driving behavior such as driving without a license. After
controlling for confounding factors, including the presence of adolescent conduct
problems, the association between attentional problems and injury-related motor vehicle
collisions remained signiﬁcant. The risks related to drunk driving; however, were no

longer statistically signiﬁcant (Woodward et al., 2000).

22

Pedestrian Safety. As pedestrian related injuries have been reported to occur
more frequently among children with ADHD than children without the disorder (DiScala
et al., 1998), research also has examined road-crossing behaviors among adolescents with
ADHD (Clancy, Rucklidge, & Owen, 2006). Results from a virtual reality hazardous
road-crossing task indicated that adolescents with ADHD (n = 24) evidenced twice as
many collisions with oncoming vehicles when compared to controls (n = 25). Further,
nearly half of the road crossings made by adolescents with ADHD resulted in low
margins of safety indicating a substantial risk for injury within a trafﬁc environment
relative to their peers. Although not examined statistically, the authors hypothesized that
inattention was a critical variable in predicting pedestrian safety (Clancy et al., 2006).
While 50% of the ADHD group had at least one other comorbid diagnosis, the inﬂuence
of these disorders was not explored within this study. Further, participants with ADHD
who were being treated with short-acting stimulant medication (n = 18) did not take their
medication on the day of testing (Clancy et al., 2006).

Injury Risk. Research has not clearly delineated the underlying or associated
features of ADHD that are responsible for the apparent increased injury risk among
children with this condition. Given the array of neuropsychological deﬁcits evident
among children in this population, it is likely that impairments in executive functioning
may play a role in injury liability. The failure to delay or inhibit responses and
difﬁculties with effortful attention are often cited as fundamental deﬁcits among children
with ADHD (Barkley, 2003; Stefanatos & Baron, 2007). Deﬁcient inhibitory control has
been linked to problems with working memory, self-regulation, internalization of speech,

and reconstitution (behavioral analysis and synthesis) (Barkley, 2003). Further,

23

disinhibition has been identiﬁed as fundamental in controlling responses to everyday
environmental events, including those that may pose a safety threat (Barkley, 1997).

Although children with ADHD appear to have increased injury liability, limited
research has investigated the extent to which these children may differ in their ability to
recognize hazardous situations, understand the consequences of engaging in risky
behavior, or identify strategies for preventing injury. In a study designed to explore these
aspects of safety knowledge, Farmer and Peterson (1995) reported that school-aged boys
with ADHD were able to identify risky behaviors and safety hazards in a manner
comparable to their typically developing peers. These children did, however, anticipate
less severe consequences of engaging in risky behavior and generated fewer methods of
preventing injuries than typically developing children. Moreover, boys with ADHD
knew fewer safety rules for risky situations than boys without ADHD (Farmer &
Peterson, 1995). Conversely, Mori and Peterson (1995) reported that school-aged boys
rated as highly impulsive and overactive did not differ from boys with low impulsivity
and overactivity ratings with respect to injury safety or prevention knowledge. Although,
participants in the later study evidenced symptoms consistent with ADHD they were not
identiﬁed as meeting diagnostic criteria for the disorder.

As research has indicated that poor parental supervision is a risk factor for
unintentional injury among typically developing children (Morrongiello et al., 2006),
Schwebel, Hodgens, and Sterling (2006) examined the role of parental supervision with
respect to increased risk for injury among children with behavior disorders. Twenty-nine
clinic-referred children were observed interacting with their mothers in a “hazard room”

which contained items that appeared dangerous but were altered to be safe. Results

24

indicated that the strongest correlate of children’s injury history (r = .51) was maternal
ignoring of behavior in the hazard room. Additionally, dangerous behavior exhibited by
children in the hazard room was most closely correlated to maternal ignoring of behavior.
Children with ODD/CD symptomatology were more likely to engage in dangerous
behavior in the hazard room than were children with only ADHD (Schwebel et al., 2006).

The presence of comorbid diagnoses also appears to place children with ADHD at
increased risk for unintentional injury. The most common comorbid disorders diagnosed
with ADHD-C are ODD and CD. The DSM-IV also identiﬁes increased risk for physical
injury as an associated feature of CD (APA, 2000). Among clinic referred children with
ADHD, over 50% will meet criteria for ODD by late childhood or early adolescence
(Barkley, 2003). Oppositional deﬁant disorder has been identiﬁed as a precursor of CD
and prevalence estimates indicate that up to half of adolescents with ADHD present with
co-occurring CD (Barkley, 2003). Thus, the developmental trajectory of ADHD suggests
that a substantial percent of these children may eventually meet diagnostic criteria for
ODD and/or CD and ADHD has been identiﬁed as one of the most reliable predicators of
the later emergence of these externalizing disorders (Stefanatos & Baron, 2007). As
such, research has explored the relationship between these clinical disorders and
unintentional injury risk.

Consistent with previous ﬁndings (Davidson, 1987), recent research has
suggested that oppositional behaviors rather than the core features of ADHD are
responsible for increased rates of unintentional injury. Schwebel, Speltz, Jones, and
Bardin (2002) conducted a two-year prospective longitudinal study to examine the

relationship between injuries among preschool-aged boys with ODD and the presence of

25

comorbid ADHD. Parents reported medically attended injuries at one and two-years
following a clinical diagnosis. Results indicated that boys with ODD had twice the
number of injuries than a matched comparison group. The presence of comorbid ADHD
in children with ODD did not increase risk for injury.

A similar pattern for injury risk emerged from a study by Schwebel and
colleagues (2007) which examined unintentional injury risk in children with externalizing
behavior disorders. They reported that among children with clinical diagnoses of ADHD,
symptoms of ODD and CD were related to injury incidence but symptoms of ADHD
were not. Observed rule violations and intentional aggression toward others were the
symptoms which predicted injury occurrence. It is important to note; however, that the
children were observed during a 6-week treatment camp for children with ADHD. As
such, the ongoing treatment regimen may have inﬂuenced the relationship between
ADHD symptoms and injury risk in this study (Schwebel, Tavares, Lucas, Bowling, &
Hodgens, 2007).

Still others have reported differential risk for injury based on psychiatric
diagnosis (Rowe, Maughan, & Goodman, 2004). After controlling for psychosocial risk
factors and comorbid psychopathology, children and adolescents with ODD were 2.3
times more likely to experience burns and 3.9 times more likely to experience a
poisoning than children without ODD. Children with ADHD were found to be at
increased risk for experiencing a fracture relative to children without ADHD. Conduct
disorder was not independently associated with any speciﬁc type of injury. The authors
concluded that ODD and ADHD rather than CD are the externalizing behavior disorders

associated with unintentional injury (Rowe et al., 2004). Thus, it is clear that controlling

26

for or assessing the impact of comorbid diagnoses is critical when examining the
relationship between ADHD and unintentional injuries.
Stimulant Medication and Unintentional Injury

The American Academy of Pediatrics (2001) recommends a target outcome of
ADHD treatment as increased safety in the community (e.g., riding bicycles, crossing
streets). This recommendation makes sense given the wealth of empirical literature
indicating that children with ADHD incur more unintentional injuries and greater medical
expenses than those without ADHD (Chan, Zhan, & Homer, 2002; Leibson et al., 2001).
Stimulant medication is the most commonly utilized treatment for children with ADHD
and methylphenidate hydrochloride (MPH) is the most frequently prescribed stimulant
(Habel, Schaefer, & Levine, 2005; Olfson, Gameroff, Marcus, & Jensen, 2003). The
trade names for MPH include Concetta, Metadate, and Ritalin. Rowland, Lesesne and
Abramowitz (2002) reported that over 1.5 million children were taking methylphenidate.
Data from 2005 indicate that amphetamine mixes accounted for 32% of medication use
while methylphenidate accounted for 47% of the ADHD medication use in 2005.
Atomoxetine accounted for nearly 17% of ADHD medication use during the same year
(Castle et al., 2007). The short-term efﬁcacy and safety of MPH treatment in children
and adolescents has been well established (MTA Cooperative Group, 1999) and
approximately 70-80% of children respond positively to stimulant medication (Pelham et
al., 2000). While MPH has been documented to improve core (i.e., inattention,
hyperactivity/impulsivity) as well as peripheral features (e.g., academic achievement)
associated with ADHD, the effects are often not great enough to normalize behavior

(Pelham et al., 2000).

27

Methylphenidate is typically considered the “gold standard” stimulant medication
treatment for ADHD, however, other psychostimulant medications including
Amphetamine (Adderall), Dextroampehtarnine (DEX; Dexedrine), and Pemoline (PEM;
Cylert) are commonly prescribed to manage symptoms of ADHD. While these
medications have not been studied as thoroughly or rigorously as MPH, research suggests
that these stimulants are comparable with MPH with respect to managing symptoms of
inattention, hyperactivity, and impulsivity in children with ADHD (Pliszka, 2007). In a
review of ADHD treatment studies, Brown and colleagues (2005) reported no clear
differences among MPH, DEX, and PEM. A limited number of controlled trials
examining of Adderall have been conducted (Manos et al., 1999; Pelham et al., 1999;
Pliszka, Browne, Olvera, & Wynne, 2000), yet these studies consistently reported that
both medications were superior to placebo and were comparable in managing symptoms
of ADHD. Speciﬁcally, Pliszka and colleagues (2000) reported that both Adderall and
methylphenidate were superior to placebo in reducing inattention and oppositional
symptoms while Adderall produced signiﬁcantly more improvements in teacher ratings
of behavior.

Trends in medication treatment for ADHD over the past several years have
reﬂected an increase in the use of extended release medication formulations relative to
immediate release or short-acting formulations (Castle, Aubert, Verbrugge, Khalid, &
Epstein, 2007). Pharmacy claims data from 2005 revealed that among children and
adolescents extended release formulations accounted for 68% of stimulant medication
usage. While similar treatment effects sizes have been reported for long-acting (.95) and

short-acting (.91) stimulant medications there are differences between these medication

28

formulations that warrant consideration. The treatment effects of immediate release
formulations typically last 2 to 4 hours and these medications are taken 2 to 4 times daily
while the effects of extended release formulations last up to 12 hours with such
medications being administered only once daily (The Medical Letter, 2006). These
differences may inﬂuence treatment adherence (Lage & Hwang, 2004; Swanson, 2003)
and may be related to a phenomenon known as the rebound effect (Carlson & Kelly,
2003). Stimulant rebound is considered to be the behavioral deterioration that occurs in
children with ADHD after medication wears off. Behaviors such as tearfulness,
irritability, and hyperactivity during this state are worse than in the unmedicated state
(Carlson & Kelly, 2003). This phenomenon has been most critically evaluated among
children treated with short-acting stimulant medications (Johnston, Pelham, Hoza, &
Sturges, 1988; Carlson & Kelly, 2003) with some research suggesting the presence of
behavioral deterioration in approximately 30% of children taking short-acting stimulants
(Carlson & Kelly, 2003). However, recent data suggest that this effect may also be
present following treatment with long-acting or extended release stimulant medications
(Cox et al., 2008). Given the relationship between children’s behavior and unintentional
injury risk, consideration of the potential for a rebound effect is justiﬁed when examining
the relationship between stimulant medication treatment and unintentional injury among
children with ADHD.

A conceptual model articulated by Rapport and colleagues (2001), outlines the
underlying components of ADHD and suggests that biological inﬂuences create
individual differences with respect to neurobiological system functioning. These

neurobiological systems are responsible for the core features of ADHD which include

29

hyperactivity, impulsivity, and inattention. This model further indicates that the
peripheral features of ADHD, as outlined in the DSM-IV (e.g., accidental injury,
academic difﬁculty) are a consequence of dysfunction associated with the core features of
ADHD. Therefore, treatments that target the neurobiological substrates, such as
stimulant medication, would impact the core features of ADHD and subsequently have a
trickle—down effect on the peripheral features, which are postulated to be derived from the
core features. As such, stimulant medication should have an effect on the rates of
unintentional injury experienced by children with ADHD.

Despite a theoretical rationale centering on the use of stimulants to reduce rates of
unintentional injury, limited research has directly explored the relationship between
stimulant medication use and unintentional injury among children with ADHD. Lage and
Hwang (2004) reported that among children with ADHD, those treated with extended
release MPH were signiﬁcantly less likely to experience a medically attended accident or
injury than those treated with immediate release MPH. In addition, extended release
MPH was associated with fewer emergency room visits and general practitioner visits. In
subsequent research, Kemner and Lage (2006) reported that children with ADHD
initiated on extended release MPH treatment were signiﬁcantly less likely to visit an
emergency room and had fewer visits to the emergency room than children initiated on
the immediate release formulation of MPH. Kemner and Lage (2006) also reported that
children whose treatment was initiated with the extended release MPH formulation had a
signiﬁcantly longer duration of medication treatment and were less likely to switch to
another ADHD medication than children who received the immediate release

formulation. Several limitations were apparent with these studies, however. The study

30

was retrospective in nature and utilized an administrative health care database.
Dependence on such data precludes conﬁrmation of an ADHD diagnosis or comorbid
conditions, directly linking speciﬁc medications to diagnoses, or determining how
effective a given medication is for a speciﬁc child (Rappley et al., 1999). Data from
medical databases are also likely to have varying levels of accuracy. Further, it is unclear
how injuries and accidents were deﬁned and measured. The authors indicated that
accidents and injuries were associated with claims for outpatient visits or hospitalizations.
As noted by Peterson and colleagues (2002), the deﬁnition of an injury that requires
medical treatment is subjective. Caregivers may opt to seek medical treatment for a
variety of reasons (e. g., child distress, medical insurance) which may ultimately result in
the inclusion of very minor injuries or the exclusion of severe injuries.

Research also has explored the relationship between stimulant treatment and
emergency department use and costs among children with ADHD (Leibson et al., 2006).
The ﬁndings revealed that while receiving stimulants, children with ADHD had
signiﬁcantly fewer emergency department visits and costs when compared to periods
during which they were not receiving stimulants. Moreover, the proportion of time on
stimulants was inversely associated with emergency department costs and visits.
Extended stimulant treatment was associated with decreased emergency department visits
and costs for children with ADHD (Leibson et al., 2006). Although fewer emergency
room visits may be associated with fewer injuries, rates of injuries were not directly
measured in this study. In addition, this study did not measure stimulant medication

treatment compliance/integrity or control for the use of additional medications.

31

Others have explored rates of unintentional injury and medical service utilization
among children treated with MPH for presumed ADHD (Brehaut, Miller, Raina, &
McGrail, 2003; Miller, Brehaut, Raina, McGrail, & Armstrong, 2004). These reports
indicated that children treated with MPH evidenced greater odds of experiencing an
injury resulting in hospital admission than those who were not treated with MPH.
Speciﬁcally, children treated with MPH were at increased risk for numerous injuries such
as fractures, poisoning, and concussions and were more likely to be injured by way of
falls, motor vehicle collisions, and pedestrian incidents (Brehaut et al., 2003). While
research has reported that MPH may reduce unintentional injuries among children with
ADHD, data from these studies suggest that stimulant medication treatment may not
“normalize” rates of injury among children with ADHD. This ﬁnding is consistent with
research on the effectiveness of stimulant medication among children with ADHD
(Pelham et al., 2000). Although these studies yield useful preliminary data they are
limited in the fact that MPH treatment may not be an accurate proxy for ADHD.
Stimulant medication is also utilized in the treatment of other child psychiatric disorders
such as autism and depression (Aman, Lam, & Van Bourgondien, 2005; Jerrell &
Shugart, 2004). Further, interpretation of the ﬁndings is hindered by the inability to
account for the impact of comorbid behavior disorders, such as ODD.

More recently, Marcus, Wan, Zhang, & Olfson (2008) reported on risk factors for
injury among children and adolescents who initiated stimulant treatment for ADHD.
They reported a higher injury risk for adolescents than children, males than females, and
for whites than minorities. Injury risk was also signiﬁcantly higher for patients

prescribed anxiolytics/hypnotics, mood stabilizers, and or antidepressants than for

32

patients not prescribed these medications and for patients treated for a comorbid mood
disorder than for patients without a mood disorder. The authors also reported a
nonsigniﬁcant trend toward an inverse relationship between stimulant medication
adherence and risk of injury. The results of this study are limited primarily by the fact
that the data were derived through medical and pharmacy claim records which may have
varying levels of accuracy. Additionally, the influence of comorbid externalizing
behavior disorders was not examined.

Other researchers have examined the impact of stimulant medication on driving
performance among adolescents and young adults with ADHD. Extended release MPH
has been reported to be superior to placebo, extended release mixed amphetamine salts
(Adderall), and immediate release MPH with respect to improving driving performance
on a driving simulator (Cox, Merkel, Kovatchev, & Seward, 2000; Cox, Merkel, Moore,
Thorndike, Muller et al., 2006; Cox, Merkel, Penberthy, Kovatchev, & Hankin, 2004).
Relative to placebo, individuals treated with MPH demonstrated less time driving off-
road, fewer instances of speeding, less erratic speed control, and less inappropriate use of
breaks on a driving simulator (Cox et al., 2006). Individuals treated with Adderall did
not demonstrate such improvements relative to placebo (Cox et al., 2006). Additionally,
extended release MPH has been shown to yield improved evening driving performance
on a computer simulator relative to immediate release MPH (Cox et al., 2004). Data also
suggest that during late evening hours, simulator and on-road driving performance
variance is signiﬁcantly greater during Adderall treatment conditions compared to long-
acting MPH treatment conditions (Cox et al., 2008). These ﬁndings have practical

implications given that a signiﬁcant percentage of motor vehicle crashes among

33

adolescents and young adults occur during the evening hours (National Safety Council,
2004). Finally, under real-life driving conditions individuals treated with controlled
release MPH evidenced fewer driving errors resulting from inattention (e. g., attending to
trafﬁc signals) relative to no medication conditions (Cox, Humphrey, Merkel, Penberthy,
& Kovatchev, 2004).

While these improvements in driving performance are postulated to reduce the
number of unintentional injuries as a result of motor vehicle crashes involving this
population, rates of injury resulting from motor vehicle crashes have not been
systematically studied in response to stimulant medication treatment.

Although a dearth of data exist regarding the relationship between stimulant
medication treatment and injuries in children with ADHD, preliminary data and a
theoretical understanding of the effects of stimulant medication indicate that future
research is warranted. In addition, research should continue to explore the differential
effects of extended release and immediate release stimulant medications on unintentional
injury as this information may ultimately impact the prescribing practices of service
providers and inform medication choices made by parents of children with ADHD.
Current Study

No research has examined the relationship between stimulant medication
treatment and minor unintentional injuries in children with ADHD, yet preliminary data
suggest that stimulant medication may serve to mitigate risk related to severe or
medically attended injuries. As noted previously, researchers have identiﬁed the utility
of studying minor injuries as a proxy for more serious medically attended injuries in

children. This study will explore the relationship between psychostimulant medication

34

treatment and minor unintentional injuries among children with ADHD. The inﬂuence of
symptom severity and the presence of comorbid symptoms on injury occurrence also will
be examined.

Research Questions

The following research questions will be addressed in the current study:

1. Are there differences in injury rates among children treated with extended release
methylphenidate and children treated with extended release mixed amphetamine salts?

Given the Conceptual model of ADHD (Rapport et al., 2001), stimulant
medication treatment which impacts the core symptoms of ADHD also should have an
effect on the peripheral features, such as unintentional injury. Research on the treatment
effectiveness of extended release methylphenidate and mixed amphetamine salts has
suggested that these drugs are equivalent in reducing the core symptoms of inattention
and hyperactivity among children with ADHD (Plizska et al., 2000). Given the proposed
relationship between these behavioral characteristics and unintentional injury, it is
hypothesized that there will be no difference in injury rates among children treated with
extended release methylphenidate and mixed amphetamine salts.

2. Does symptom severity predict minor unintentional injury among children with
ADHD?

Although limited research has investigated the impact of ADHD symptom
severity on injury, Nada-Raja and colleagues (1997) reported that increased symptom
severity predicted negative driving outcomes for adolescents. Moreover, Schwebel and
colleagues (2005) indicated that hyperactivity was a strong predictor of injury among

young children. It is therefore hypothesized that children with increased ADHD

35

symptom severity (i.e., hyperactivity, inattention) will experience a greater number of
minor unintentional injuries.

3. Does the presence of symptoms ofcomorbid externalizing behavior disorders predict
minor unintentional injury among children with ADHD?

Several studies have revealed that the presence of comorbid ODD and/or CD
symptoms is associated with increased injury risk among children and adolescents with
ADHD (Schwebel et al., 2002; Rowe et al., 2004). As such, it is hypothesized that
children who have elevated scores on the ODD and/or CD scales of the Child Behavior
Checklist will incur more injuries than children who do not exhibit signiﬁcant comorbid
symptomatology.

4. What is the relationship between minor and severe unintentionally injuries among
children with ADHD?

A positive association between minor and severe injuries has been reported
among typically developing children within the literature (Morrongiello et al., 2004).
Moreover, J aquess and F inney (1994) reported that the occurrence of a severe injury was
associated with subsequent minor injuries. It is hypothesized that the nature of this
relationship will hold true for children with ADHD. Speciﬁcally, it is hypothesized that
children who experience a medically attended injury will be more likely to incur

subsequent minor injuries.

36

Chapter 3

METHOD
Participants

The participants in the current study included 31 parents of school-aged children
between the ages of 5 and 12. Participants were recruited from Michigan and Connecticut
and are from predominately middle-class suburban communities. The demographic
characteristics of the sample reﬂected national service utilization data which suggest that
Caucasians are more likely to utilize stimulant medication than minority children (Cox,
Motheral, Hendersen, & Mager, 2003). Further, this study also revealed a male-to-female
ratio similar to the 3:1 ratio reported within current literature (Strine et al., 2006).

To be included in the study children were required to have a current diagnosis for
one of the three subtypes of ADHD (e. g., predominately inattentive, predominately
hyperactive-impulsive, combined type) as determined by parent report of a clinical
diagnosis and/or parent behavioral rating scales. Children who were treated
pharrnacologically must have received a consistent dosage level and formulation of
stimulant medication for no less than 4 weeks prior to beginning the study in order to
establish a stable pattern of treatment. Participants were excluded if their children were
receiving any type of psychopharmacological treatment not indicated as a ﬁrst-line
treatment of ADHD (e. g., antidepressants). Given that the purpose of several research
questions was to examine the relationship between symptom severity and unintentional
injury, children with a diagnosis of ADHD who were not treated phannacologically were
permitted to enroll in the study. However, data for these children were only included in
analyses which did not examine the impact of medication treatment on injury. Finally, in

order to participate in the proposed study, parents were also required to indicate intent to

37

maintain the treatment utilized at the beginning of the study (e. g., medication, no
medication) for the duration of the study. From the larger sample, two secondary groups
of participants were identiﬁed: parents of children with ADHD who were receiving
extended release methylphenidate treatment (N = 9) and parents of children with ADHD
who were treated with extended release mixed amphetamine salts (N = 10). To be
included in the subgroup analysis children could not be taking multiple medications
concurrently (e. g., extended release in conjunction with immediate release formulation)
or a medication not classiﬁed as a long-acting psychostimulant (e. g., Strattera).
Psychostimulants classiﬁed as extended release mixed amphetamine salts included
Adderall XR. Psychostimulants classiﬁed as extended release methylphenidate included
Concerta, Metadate ER, Focalin XR, and Ritalin LA. Due to initial recruitment
difﬁculties institutional review board approval was obtained to provide participants who
enrolled in the study after February 2008 with a $25 stipend for participation.

Materials

Parents completed the following measures:

Demographic Information Questionnaire. An investigator developed
questionnaire was utilized to obtain information regarding child age, sex, ethnicity,
psychiatric diagnoses, and medication treatment regimen (i.e., dosage and formulation).
Data regarding parental education, parental employment status, and family composition
was also collected.

Vanderbilt A DHD Parent Rating Scale (VADPRS). The VADPRS is a 55-item
measure that includes all 18 DSM-IV criteria for ADHD. The scale also includes criteria

for ODD and CD as well as items that screen for anxiety and depression. Each item

38

related to psychopathology is rated on a 4-point scale (i.e., never, occasionally, often,
very often). The VADPRS also contains a performance scale related to academic
performance and relationships. These items are rated on a 5-point scale (i.e., excellent,
above average, average, somewhat of a problem, problematic). The psychometric
properties of the VADPRS have been reported in one study within the literature
(Wolraich et al., 2003). Internal consistency alpha coefﬁcients were reported as >90 for
parent ratings within a clinical sample of over 200 children. A concurrent validity
coefﬁcient of .79 was reported with the Diagnostic Interview Schedule for Children- IV
(DISC-IV), which has well-established reliability and validity (Shaffer, Fisher, Lucas,
Dulcan, & Schwab-Stone, 2000). Additionally, internal consistency reliabilities of the
DISC-IV and VADPRS were .93 or higher (Wolraich et al., 2003).

Child Behavior Checklist — Parent (CBCL). The Behavior Problems Scale of the
CBCL (Achenbach & Rescorla, 2001) consists of 1 13 items which are rated on a 3-point
scale (i.e., not true, somewhat or sometimes true, and very or often true). Scores fall in
clinical, borderline, or normal range. This scale includes a total problems behavior index
comprised of two broad-band factors, Extemalizing and Intemalizing Syndromes. The
Extemalizing factor includes problem behaviors such as hyperactivity and aggression,
whereas the Intemalizing domain includes anxious and depressive behaviors. The CBCL
also has DSM-oriented scales which include oppositional deﬁant problems, conduct
problems, attention-deﬁcit/hyperactivity problems, affective problems, and anxiety
problems which will be used to assist in identifying children with comorbid psychiatric
conditions. Recent data indicate that the CBCL is a useful measure to screen for

comorbid disorders among children with ADHD (Biederman, Monuteaux, Kendrick,

39

Klein, & Faraone, 2005). The CBCL is probably the most researched behavior rating
scale for children and has adequate to excellent psychometric characteristics (Lengua,
Sadowski, Friedrich, & Fisher, 2001). Test-retest alpha coefﬁcients range from .82 to
.97, indicating high reliability. Further, the CBCL accurately differentiates between
clinically-referred and non-referred children. A computer scoring program was used to
generate behavioral proﬁles for each of the participants. Data was entered into the
program on two occasions to ensure reliable data entry.

Behavior Assessment System for C hildren-Monitor for ADHD - Parent (BASC-
Monitor). The BASC-Monitor is a norm-referenced rating scale used to measure attention
problems, hyperactivity, internalizing problems, and adaptive skills (Kamphaus &
Reynolds, 2001). The form is ideal for repeated use during treatment evaluation. The
rating form uses a simple four point response scale for each behavior, ranging from
"Never" to "Almost Always." Internal reliability alpha coefﬁcients range from .67 to .85
while test-retest reliabilities range from .60 to .90. Validity has been demonstrated
through high correlations between the BASC-Monitor and the CBCL. The BASC-
Monitor also has been found to differentiate between ADHD subgroups and non-ADHD
children. A computer scoring program was used to generate behavioral proﬁles for each
of the participants. Data was entered into the program on two occasions to ensure
reliable data entry.

Minor Injury Severity Scale (MISS). The MISS allows for objective assessment of
injuries which do not necessitate medical intervention. This measure is sensitive to minor
injuries and categorizes injuries into 22 types (e. g., cut, bruise/bump, burn). Injuries are

rated on a 7—point severity scale to quantify tissue damage. For the purposes of this study

40

severity ratings will not be determined. The measure is an accepted and widely-cited
instrument for studying minor unintentional injury. The MISS has demonstrated
adequate reliability and stability (Peterson et al., 1996). Test-retest reliability was
reported at .99 and intercoder reliability was reported at .71. Divergent validity data on
the MISS indicates that measured tissue damage is related to but not the same as injury
outcomes such as pain, fear, and disability.

Injury History Questionnaire (IHQ). This measure provides an index of the
frequency during the past several months with which the child has sustained moderate to
severe injuries, which include medically attended injuries. The higher the score the more
frequently the child had sustained non-minor injuries. Reliability and validity data have
not been reported within the literature; however, this instrument has emerged as a useful
tool in the study of unintentional injury (see Morrongiello et al., 2006; Morrongiello et
al,2004)

Procedures

Participants were recruited from medical clinics and schools via public outreach
efforts. Over 200 letters describing the study were mailed to physicians, psychiatrists,
psychologists, and school counselors throughout multiple states (Michigan, Ohio,
Connecticut, and North Carolina). Informational ﬂyers were included with these letters
for distribution to patients by medical and/or mental health providers. An e-mail
describing the study with the informational ﬂyer attached was distributed to over 100
school psychologists registered with the Michigan Association for School Psychologists.
Additionally, informational ﬂyers were posted in libraries throughout central Michigan.

Upon recruitment, informed consent was obtained and an ADHD diagnosis was

41

conﬁrmed through parent report of physician diagnosis and completion of the VADPRS
by telephone interview. To assess for symptoms associated with comorbidity, the CBCL
was administered prior to beginning bi-weekly data collection. Participants were enrolled
in one 4-week interval of data collection over a nine month period. Data collection
across the year served to control for potential seasonal variation in injury rates. The
BASC-Monitor for ADHD was administered weekly during the 4-week interval to
measure levels of inattention and hyperactivity. Reported injuries were coded and
quantiﬁed through the use of minor unintentional injury rating scales. These logs were
completed through bi-weekly phone calls to parents during the 4-week interval. Parents
also completed an Injury History Questionnaire upon study enrollment to report the
frequency with which the child sustained moderate to severe injuries in the previous 3
months. Prior research indicates that parents accurately recollect childhood injury
information for more serious injuries (Pless & Pless, 1995), but their recollection for
minor injuries is poorer (Peterson, Harbeck, & Moreno, 1993). For these reasons it was
appropriate for severe injuries to be reported using 3 month recall measures while minor
injuries were reported bi-weekly. Integrity of medication treatment was monitored
weekly throughout the study. Parents reported on the number of days the child took
medication each week as prescribed well as the dose and formulation of the medication.
Research Design & Data Analysis

The design of the present study afforded the opportunity to glean a clearer
understanding of the relationship between different formulations of psychostimulant
medications and minor unintentional injury as well as the relationship between symptom

severity and minor unintentional injury among children with ADHD. Unintentional

42

injuries in school-aged children with ADHD treated with extended release
methylphenidate and children treated with extended release mixed amphetamine salts
were compared using a between subjects, non-equivalent control group design. Analysis
of covariance (ANCOVA) was used to test the differences related to minor unintentional
injuries between the two groups. This speciﬁc method of data analysis was selected as
the use of covariates statistically reduces the error variance, and therefore increases the
relative effect size. Further, this statistical technique can increase the power of a
treatment effect in between subjects designs with small sample sizes (Algina & Olenjnik,
2003). Additionally, Stevens (1996) recommends the use of two or three carefully chosen
covariates to reduce error variance with small sample sizes. The analysis in this study
employed three covariates related to ADHD symptom severity as well as the presence of
symptoms associated with comorbid externalizing behaviors disorders (i.e., ODD and
CD). This analysis allowed for the investigation of the impact of these covariates on
rates of minor injury among the groups. The dependent measure, minor unintentional
injuries was entered as a continuous variable.

Prediction models using linear regression analysis were examined for minor
unintentional injuries. Prior to examining the prediction models, group differences in
minor injuries and potential predictor variables were examined using the Mann-Whitney
U Test. This is a non-parametric alternative to the t—test for independent samples, and is
often employed when variables are nonnorrnally distributed. The two groups were
compared on several characteristics including gender, age, parental education, injury
history, scores on the attention-deﬁcit/hyperactivity problems, conduct problems, and

oppositional deﬁant problems DSM-oriented scales from the CBCL, and mean weekly

43

hyperactivity and attention problem scores from the BASC-Monitor. An alpha level of
.01 was used for all between group analyses to control for inﬂated experiment-wise Type
1 error.

To investigate the association between ADHD symptom severity and minor
unintentional injury, four separate linear regression analyses were conducted to examine
the relationship between weekly levels of hyperactivity and attention problems as
measured by the BASC-Monitor and the number of unintentional injuries reported during
each respective week. For each of the separate regression analyses, the total number of
weekly unintentional injuries was entered as a continuous dependent variable. Weekly
hyperactivity and attention problem scores were entered as independent variables using
backward deletion procedures.

Hierarchical linear regression was utilized to examine the contribution of multiple
predictor variables on minor unintentional injury. In the ﬁrst step of the model, the
presence of comorbid symptoms associated with conduct disorder was examined using
scores from the CBCL. Next, ADHD symptom severity (i.e., inattention, hyperactivity)
as measured by the CBCL, was entered into the model. Finally, the contribution of
severe injury history as measured via parent report of a medically attended injury on the
IHQ was examined.

Bijur, Golding, and Haslum (1988) recommend that risk ratios be calculated for
low base-rate events such as unintentional injury in order to more adequately reﬂect their
relationship with predictor variables. An odds ratio which provides an estimate of
relative risk was calculated. To this end, logistic regression analysis was performed to

predict the presence or absence of a medically attended injury. A lifetime history of

44

medically attended injury was utilized as only 3 children experienced an injury serious
enough to warrant medical attention during the course of the study and all children
experienced at least one minor injury throughout the course of the study. Age, ethnicity,
number of children living in the household, and number of minor unintentional injuries

experienced since birth were entered as independent variables in the regression model.

45

Chapter 4

RESULTS

Descriptive Statistics

Thirty-three parents of children diagnosed with attention-dcﬁcit/hyperactivity
disorder (ADHD) participated in the study. Data are only reported for 31 children as one
participant was identiﬁed as an extreme outlier in terms of the number of weekly minor
unintentional injuries reported and another was identiﬁed as an outlier with respect to
consistently extreme weekly hyperactivity scores. Table 1 displays the demographic
characteristics of children in the sample, including age, gender, ethnicity, parental
education, and household type. Twenty-eight of the children were reported to be taking
medication for the management of ADHD symptoms while 3 children were not taking
medication. Table 2 provides a breakdown of the types of medication prescribed. The
duration of medication treatment prior to study enrollment ranged from 1 to 60 months
(M = 26.67, SD = 19.89).

Clinical Symptoms. Descriptive statistics concerning the clinical features of
children as reported by their parents are presented in Tables 3 and 4. Mean scores along
with standard deviations are provided for the scales comprising the Child Behavior
Checklist (CBCL) and Behavior Assessment System for Children-Monitor for ADHD
(BASC-Monitor). Based on data derived from the Vanderbilt ADHD Rating Scales
(VADPRS) upon study enrollment, 10 children met criteria for ADHD predominately
inattentive type, 1 child met criteria for ADHD predominately hyperactive type, 4 met
criteria for ADHD combined type, and 5 children met criteria for Oppositional Deﬁant

Disorder. Sixteen children did not meet criteria for any of the ADHD diagnostic

46

categories based on scores from the VADPRS. The average total ADHD symptom score
was 7.96 with a standard deviation of 3.87. The mean performance score was 2.91 with a
standard deviation of .607. Table 5 displays the correlations among scores on the
behavioral rating scales utilized to measure symptom severity and the presence of
comorbid symptoms.

Unintentional Injuries. As a part of descriptive analyses, the ecological aspects of
injuries children experienced were also considered. The number of injuries each child
incurred within the 4-week period ranged from 3 to 62 injuries, with a mean of 5.5 (SD =
4.2) injuries per week. The mean number of injuries experienced during the course of
entire the study was 22 (SD = 16.8, Median = 16). Children experienced an average of
7.2 injuries during the ﬁrst week, 4.6 during the second week, 5.1 during the third week,
and 5.2 during the fourth week of the study. The most commonly reported minor injures
were bruises and bumps followed by scrapes and scratches. Based on the Injury History
Questionnaire, children experienced an average of 11.3 minor injuries and 3.5 moderate
injuries within the past 3 months. The average number of lifetime medically attended
injuries ranged from O to 20, with a mean of 2.8. Only 1 child had ever been hospitalized
because of an injury. The most common injuries reported to have been experienced by
children since birth included cuts and falls from moving objects. During the course of the
study, 3 children were reported to receive medical attention for an injury.

Relationships among Clinical Symptoms and Unintentional Injuries.

Visual inspection of histograms, normal Q-Q plots, and detrended normal Q-Q

plots as well as the Kolmorgorov-Smimov statistical test of normality revealed that the

injury data were non-normally distributed. Correlation coefﬁcients were calculated using

47

Spearman’s rho, a non-parametric alternative to the Pearson product-moment correlation
coefficient, to examine relationships between clinical symptom scores derived from the
behavior ratings scales and number of parent-reported injuries. There were several strong
positive correlations between the number of minor unintentional injuries experienced
during the study and parent-reported clinical symptoms. Signiﬁcant correlations emerged

among total number of minor unintentional injuries and the CBCL conduct problems

DSM-oriented scale (rS .744, p = .002); CBCL attention-deﬁcit/hyperactivity problems

DSM-oriented scale (rS .639 , p < .001 ); CBCL oppositional deﬁant DSM-oriented
scale (r5 = .648, p < .001); CBCL attention problems (r5 = .705, p < .001); CBCL somatic
problems (rS = .596, p = .001); CBCL rule breaking behavior (r5 = .659, p < .001); CBCL
aggressive behavior (rs = .676, p < .001); VADPRS total ADHD symptoms (rs = .403, p =
.015); BASC-Monitor mean weekly hyperactivity (rS = .437, p = .014); and, the BASC—
Monitor mean weekly attention problems (rS = .383, p = .033).

Several signiﬁcant correlations were found between number of unintentional
injuries as measured by the Injury History Questionnaire and clinical symptom scores.
The number of minor injuries since birth was positively correlated with the CBCL
conduct problems DSM-oriented scale (rS = .372, p = .047); CBCL attention-
deﬁcit/hyperactivity problems DSM-oriented scale (rs = .455, p = .010); CBCL attention
problems scale (rs = .673, p < .001); and the VADPRS total ADHD symptom (rs = .370, p
= .041). No statistically signiﬁcant correlations were found among minor injuries in the
previous 3 months and clinical symptom scores. Moderate injuries since birth were

signiﬁcantly correlated with the CBCL attention-deﬁcit/hyperactivity problems DSM-

oriented scale (rS = .367, p = .043) and the CBCL attention problems scale (rs = .538, p =

48

.002). Moderate injuries experienced in the past 3 months were signiﬁcantly correlated
with CBCL somatic problems scale (rs = .416, p = .025) and the CBCL attention
problems scale (rs = .362, p = .047). There was a moderate positive correlation between
the number of medically attended injuries experienced since birth and the CBCL somatic
problems scale (r8 = .407, p = .029). No statistically signiﬁcant relationships were found
between the number of medically attended injuries experienced during the previous 3
months and any of the clinical symptom scores.
Research Question 1: Medication Treatment

Employing a subgroup analysis of the 28 children treated with medication, this
research question examined differences in injury rates among children treated with
extended release methylphenidate (N = 9) and children treated with extended release
mixed amphetamine salts (N = 10). A one way between subjects analysis of covariance
(ANCOVA) was used to test the differences related to minor unintentional injuries
between the two groups. The analysis employed three covariates: the CBCL ADHD
problems DSM-oriented scale, CBCL oppositional deﬁant problems DSM-oriented scale,
and CBCL conduct problems DSM-oriented scale. The dependent measure, minor
unintentional injuries was entered as a continuous variable. Preliminary checks were
conducted to ensure that there was no violation of the assumptions of normality, linearity,
homogeneity of variances, homogeneity of regression slopes, and reliable measurement
of the covariates. Given the nonnormal distribution of minor unintentional injury, a
square root transformation was employed on the dependent variable. Visual examination
of the histogram, normal and detrended normal Q-Q plots as well as the Kolmorgorov-

Smimov statistical test of normality indicated that the transformation was successful and

49

yielded normal distributions for the minor unintentional injury variable. After adjusting
for scores of ADHD symptom severity and comorbid symptom severity, there was no
signiﬁcant difference between the two medication treatment groups in the number of
minor unintentional injuries reported F (1,13) = .58, p = .46, partial eta square = .041.

The adjusted mean injury score for the medication group treated with extended release
methylphenidate was 4.37 compared with an adjusted mean injury score of 3.83 for the
group of children treated with extended release mixed amphetamine salts. There was a
signiﬁcant relationship between the scores on the CBCL conduct problems DSM-oriented
scale and minor unintentional injuries, p = .041, partial eta square = .285.

Using the Mann-Whitney U Test, a non-pararr’retric alternative to the t-test for
independent samples, these groups of children were compared on several characteristics
including gender, age, parental education, injury history, scores on the attention-
deﬁcit/hyperactivity problems, conduct problems, and oppositional deﬁant problems
DSM-oriented scales from the CBCL, and mean weekly hyperactivity and attention
problem scores from the BASC-Monitor. Results indicated that no signiﬁcant differences
emerged between the groups on any of the above characteristics. Given sample size of 19
for this analysis, the power to detect signiﬁcant between group differences with an effect
size of .25 was less than .20.

Medication treatment integrity was also assessed throughout the course of the
study. Fifty-seven percent (N = 16) of children took their medication as prescribed
during each week of the study. Twenty-nine percent (N = 8) took their medication as
prescribed on a daily basis for 3 of the 4 weeks. Fourteen percent (N = 4) took their

medication as prescribed during 2 weeks or fewer across the 4 week period. No

50

statistical differences were found in number of injuries incurred by children based on
level of medication treatment integrity. No relationship was found between length of
medication treatment prior to study enrollment and number of parent-reported minor

unintentional injuries. '

Research Question 2: ADHD Symptom Severity

The second research question of this study examined the relationship between
ADHD symptom severity and minor unintentional injuries. Four separate linear
regression analyses were conducted to examine the relationship between weekly levels of
hyperactivity and attention problems as measured by the BASC-Monitor and the number
of unintentional injuries reported during each respective week. For example,
hyperactivity and attention problem scores from week 1 were regressed on total number
of minor unintentional injuries reported in week 1. For each of the separate regression
analyses the total number of unintentional injuries was entered as a continuous dependent
variable. Standardized T-scores based on age and gender norms for hyperactivity and
attention problems derived from the BASC-Monitor were entered as independent
variables using backward deletion procedures.

Preliminary analyses were conducted to ensure no violation of the assumptions of
normality, linearity, multicollinearity, and homoscedasticity. Examination of the data
revealed that several of the continuous variables were non-normally distributed. For each
of these variables a square root transformation was employed. Visual examination of
histograms, normal and detrended normal Q-Q plots as well as the Kolmorgorov-Smirnov

statistical test of normality indicated that the transformations were successful and yielded

normal distributions for each of the variables.

51

Since age and gender are factors known to inﬂuence injury, a preliminary analysis
was conducted to determine whether these variables should be controlled for in the
regression models. Age was collapsed into two groups, with children ages 5 to 8
comprising the ﬁrst group and children ages 9 to 12 comprising the second group. Results
revealed that there was no relationship between age, gender, and injury in this study, so
these variables were excluded from the regression analyses.

Signiﬁcant regression models are presented in Table 6. The regression model for
unintentional injuries incurred during week 1 was nonsigniﬁcant. Neither level of
hyperactivity or attention problems were signiﬁcant predictors of the number of injuries
reported. For week 2, attention problems signiﬁcantly predicted injuries following
removal of hyperactivity from the initial model, F (1, 29) = 4.97, p = .034. In the ﬁnal
model attention problems accounted for 15% of the variability in injuries. The model
including both hyperactivity and attention problems as predictors of injury for week 3
was signiﬁcant, F (2, 28) = 4.92, p = .015. Together these variables accounted for 26%
of the variance in the model; however, neither measure was independently statistically
signiﬁcant. Following removal of attention problems from the model, hyperactivity
contributed signiﬁcantly to the model F (1, 29) = 7.63, p = .010, accounting for 21% of
the variance. Injuries reported in week 4 were also signiﬁcantly predicted by measured
levels of hyperactivity and attention problems, F (2, 28) = 4.28, p = .024, with these
variables accounting for 23% of the variance in this regression model. Again neither
measure was independently statistically signiﬁcant when both were included in the

model. Following deletion of hyperactivity from the regression model, attention

52

problems contributed signiﬁcantly to the model, F (l, 29) = 8.04, p = .008, accounting for
22% of the variance.

Mean ADHD symptom scores across the four week study period were calculated
and regressed on mean number of weekly injuries reported. Consistent with the previous
models, hyperactivity and attention scores were entered into the regression model using
backward deletion procedures. The initial model including both hyperactivity and
attention problems as predictor variables approached signiﬁcance, F (2, 28) = 3.11, p =
.060. Removal of attention problems from the model, yielded a signiﬁcant ﬁnal model, F
(1, 29) = 5.62, p = .025, with hyperactivity accounting for 16% of the variability in
injuries.

Additionally, a regression analysis was conducted to determine if parent-reported
ADHD symptoms at the beginning of the study predicted the occurrence of minor injuries
throughout the duration of the study. The initial model which included three predictor
variables, CBCL attention problems syndrome scale, CBCL ADHD problems DSM-
oriented scale, and the VADPRS total ADHD symptom score, was statistically
signiﬁcant, F (3, 27) = 4.57, p = .010. Only in the ﬁnal model, which included the CBCL
ADHD problems DSM-oriented scale, did a single measure signiﬁcantly predict minor
injuries, F (1, 29) = 14.31, p = .001. The ﬁnal model accounted for 33% of the variance
among minor unintentional injuries.

Finally a one-way between group analysis of covariance (ANCOVA) was
conducted to examine differences in the number of minor unintentional injuries among
children who met criteria for one of the three subtypes of ADHD based on the VADPRS

(N = 15) upon study enrollment and those who did not meet such criteria (N = 16). After

53

 

adjusting for scores on the CBCL conduct problems DSM-oriented scale, there was no
signiﬁcant difference between the children who met VADPRS diagnostic criteria (M =
24.58, SD = 16.77) in the number of minor unintentional injuries reported F (1, 26) =
.001, p = .978. There was a signiﬁcant relationship between scores on the CBCL conduct
problems DSM-oriented scale and minor unintentional injuries, p < .0001 , partial eta
square = .285.
Research Question 3 .' Comorbid Symptoms

This research question examined the inﬂuence of comorbid symptoms on rates of
unintentional injuries experienced by children during the course of the study. A
regression analysis was utilized to assess the impact of comorbid symptoms associated
with externalizing behavior disorders as measured by the CBCL on childhood injuries.
Speciﬁcally, the conduct problems DSM—oriented scale score and oppositional deﬁant
problems DSM-oriented scale score were entered as continuous independent variables.
An examination of tolerance and the variable inﬂation factor indicated potential problems
with multicollinearity when rule-breaking behavior and aggressive-behavior syndrome
scale scores were included in the model, thus those variables were omitted from the
model. The regression model including conduct problems and oppositional deﬁant
problems was signiﬁcant, F (2, 26) = 14.05, p < .001, accounting for 52% of the variance
in injuries. However, only the conduct problems scale contributed signiﬁcantly to the
model (beta = .579, p = .016), indicating that children with elevated conduct problems
were more likely to experience subsequent minor injuries.

Hierarchical multiple regression was used to assess the ability of the CBCL

attention-deﬁcit/hyperactivity problems DSM-oriented scale to predict injuries after

54

controlling for the inﬂuence of the CBCL conduct problems DSM-oriented scale. The
conduct problems scale was entered at Step 1, explaining 50% of the variance (beta =
.706), F (1, 27) = 26.86, p < .001. After entry of attention problems scale at Step 2, the
total variance explained by the model as a whole was 51%, F (2, 26) = 13.38, p < .001.
The attention-deﬁcit/hyperactivity problems DSM-oriented scale (beta = .133) explained
less than an additional 1% variance in injuries, after controlling for conduct problems, R-
square change = .008. In the ﬁnal model, only the conduct problems DSM-oriented scale
was statistically signiﬁcant (beta = .610) in terms of predicting the occurrence of minor
unintentional injuries.
Research Question 4: Unintentional Injuries

The ﬁnal research question examined the relationships between minor, moderate,
and medically attended unintentional injuries. Relationships between parent-reported
injuries based on the Minor Injury Severity Scale and the Injury History Questionnaire
were computed and correlations among the variables are presented in Table 7. Given the
nonnormal distribution of the injury history variables, correlations were calculated using
Spearman’s rho non-parametric alternative.

The relationship between injuries was also explored using regression analyses.
Given that a normal distribution is an underlying assumption of regression analyses,
injury history variables were transformed using logarithmic transformations (Log10).
While these transformations improved the distribution of the minor and moderate injury
history variables, the large number of participants who had not experienced a medically
attended injury limited the utility of statistical transformation for these variables. As such,

medically attended injury history variables were excluded from the following regression

55

analysis. Employing a backward elimination procedure, minor and moderate injury
history variables were regressed on minor unintentional injuries. The only signiﬁcant
predictor of minor injuries was the number of parent-reported minor injuries experienced
since birth, F (1, 20) = 4.63, p = .044. The total variance explained by the ﬁnal model,
which included only one predictor, was 18%. Parent-reported moderate injuries and
minor injuries over the past 3 months failed to contribute signiﬁcantly to the ﬁnal model
that predicted minor unintentional injuries.

To examine whether or not a history of minor injuries was able to predict
unintentional injuries after controlling for the presence of conduct problems, hierarchical
multiple regression was utilized. The conduct problems scale was entered at Step 1,
explaining 50% of the variance, F (1, 27) = 26.86, p < .001. After entry of minor injury
history at Step 2, the total variance explained by the model as a whole was 56%, F (2, 26)
= 16.50, p < .001. The minor injury history measure explained an additional 6% variance
in injuries, after controlling for conduct problems, R-square change = .061. In the ﬁnal
model only the conduct problems DSM-oriented scale was signiﬁcant and recorded a
higher beta value (beta = .635, p < .001) than the history of minor injuries (beta = .265, p
= .070).

Binary logistic regression was performed to assess the impact of a number of
factors on the likelihood that children had ever experienced a medically attended injury.
A total of 31 observations were included in the analysis, with 8 observations included in
the “1” category and 23 included in the “0” category. The model contained four
independent variables (age, ethnicity, number of children living in the household, and

number of minor unintentional injuries experienced since birth). The full model

56

containing all predictors was statistically signiﬁcant, )8 (4, N = 31) = 14.94, p = .005,
indicating that the model was able to distinguish between children who had and had not
experience a medically attended injury. An examination of regression diagnostics
indicated that there were no outliers or inﬂuential data points. The Hosmer and
Lemeshow goodness-of-ﬁt test was nonsigniﬁcant. The model as a whole explained
between 38.2% and 56.2% of the variance in injury occurrence, and correctly classiﬁed
87.1% of the cases. The strength of the prediction was .38 according to Cox’s and
Snell’s R2. As shown in Table 8, three of the independent variables made a unique
statistically signiﬁcant contribution to the model (number of children living in household,
child age, and number of minor injuries experienced since birth) while ethnicity
approached statistical signiﬁcance. Parents who reported fewer children living in the
household were likely to have a child who had experienced a medically attended injury as
compared to those who reported households with a greater number of children (OR =

.198, 95% CI = 057—690.).

57

Chapter 5
DISCUSSION

This study examined differences in minor unintentional injuries among children
with attention-deﬁcit/hyperactivity disorder (ADHD) who were treated with long-acting
methylphenidate and extended release mixed amphetamine salts. Further, this study
explored the extent to which severity of hyperactivity and inattention symptoms placed
children at risk for incurring minor unintentional injuries. The impact of symptoms of
comorbid externalizing behavior disorders on injury was also investigated. Finally, the
relationship between minor and medically attended injuries among children diagnosed
with ADHD was examined. This study offers a unique contribution to the literature
considering psychopathology and injury because it only included children diagnosed with
ADHD, and those children were followed prospectively for 4 weeks to track injury
occurrences and behavior disorder symptoms.
Unintentional Injuries

Results on the ecology of injuries among this sample paralleled results from
research with disordered (Schwebel et al., 2007) and non-disordered children
(Morrongiello et al., 2004; Schwebel et al., 2002). In the current study, children
experienced bumps and bruises most often followed by scrapes and scratches. This is
consistent with results reported by Schwebel and colleagues (2007) who examined
unintentional injuries in children with externalizing behavior disorders and reported that
these children most frequently experienced bumps and bruises (53% of injuries) followed

by cuts and scrapes (32% of injuries).

58

A difference between this study and previous research centers on the frequency of
injury. The rate of injury in this study was high with parents reporting an average of 5.5
minor unintentional injuries per week. This rate is signiﬁcantly higher than the average
(2.18) number of injuries Schwebel et al. (2007) reported among behavior disordered
children across a 6-week period. A potential rationale for this large discrepancy centers
on how injuries were measured. The current study focused speciﬁcally on parent-reported
minor unintentional injuries while Schwebel and colleagues (2007) utilized observations
from camp counselors who coded injuries requiring adult attention or those which leﬁ
tissue damage lasting at least 10 minutes. Children may be more likely to report minor
injuries to their parents than unfamiliar camp counselors and parents may be more likely
than camp counselors to observe minor tissue damage for their individual child. The
children enrolled in the study conducted by Schwebel and colleagues (2007) were
attending a summer camp for children with ADHD and thus injury rates may have been
inﬂuenced by ongoing behavioral treatment regimens utilized as a part of the structured
camp protocol. Moreover, poor adult supervision has been associated with injury risk and
the level of close supervision provided at camp would likely inﬂuence injury rate.
Finally, an elevated frequency in injury rate observed in the current study may also stem
from response bias or self-selection of participants. Given the expansive recruitment
process, yet limited number of participants enrolled in the study, it is plausible that
parents chose to participate in the study because their children had a history signiﬁcant

for injuries or because they experienced injuries on a regular basis.

59

Medication Treatment

A discussion of between group differences with respect to medication treatment
must be qualiﬁed by fact that given the small sample the power to detect statistical
signiﬁcance in the current study was less than .20. Thus, interpretive conclusions are
limited as it is unclear if there was sufﬁcient power to detect group differences if they
were present in the current sample. No signiﬁcant relationships between medication
treatment patterns and unintentional injuries emerged from the current study.
Speciﬁcally, no differences in the number of parent-reported unintentional injuries were
evident among children treated with extended release methylphenidate and children
treated with extended release mixed amphetamine salts. Yet, it is important to note that
the frequency of minor injuries was high in both groups. While no previous research has
examined the differential impact of these speciﬁc medications on injury occurrence, data
from research on adolescent driving performance do seem to suggest that these
medications have a differential impact on negative driving outcomes (Cox et al., 2006;
Cox et al., 2008). Speciﬁcally, both simulated and on—road driving performance was
compromised among adolescents during extended release mixed amphetamine salts
compared to long-acting methylphenidate conditions. Importantly, these studies only
reported differential medication effects in the late evening. Children in the current study
would likely be sleeping at those times and would not be engaged in behavior that placed
them at-risk for experiencing injury. Therefore, the differential medication impact on
behavior observed in the late evening may be irrelevant when considering injury rates in

the current study. Additionally, the studies by Cox and colleagues (2006; 2008) focused

60

on driving performance and thus examined a behavior believed to place adolescents at-
risk for incurring unintentional injury rather than reporting on actual injury occurrences.
In the current study, children treated with methylphenidate and mixed
amphetamine salts did not differ with respect to parent-reported ADHD symptom
severity. This ﬁnding matches results from recent studies demonstrating equivalent
effectiveness of different drugs in managing the behavioral symptoms of ADHD (Pliska
et al., 2000). The majority of children in the current study were treated with extended
release or long-acting rather than immediate release or short-acting medications. This is
consistent with reported trends in the medication management of ADHD which highlight
an increase in prescription rates of long-acting or extended release medications (Castle et
al., 2007). This shift in prescribing patterns may be related to increased treatment
adherence associated with long-acting medications (Lage & Hwang, 2004; Swanson,
2003) and/or an observed rebound effect which has been investigated in children with
ADHD treated immediate release or short-acting medications (Johnston et al., 1988;
Carlson, Kelly, et al., 2003). This phenomenon involves the worsening of ADHD
symptoms beyond baseline as medication wears off (e. g., between doses) and has been
implicated in poor driving outcomes for adolescents with ADHD who are treated with
short-acting stimulant medication (Cox et al., 2004). However, recent data have also
revealed potential rebound effects following the use of extended release mixed
amphetamine salts (Cox et al., 2008; McGough et al., 2003; Swanson et al., 2004). Given
the recent shift in prescribing patterns resulting in an increased use of long-acting
medications for the treatment of ADHD symptoms future research on rebound effects is

warranted as it relates to behaviors placing children at increased risk for injury.

61

The current study reported no relationship between duration of medication
treatment and minor unintentional injury. Previous research has reported a relationship
between medication treatment length and medically attended injuries (Leibson et al.,
2006). Speciﬁcally, the proportion of time on stimulant medication was inversely
associated with emergency department visits such that extended stimulant medication
treatment was associated with decreased emergency department visits for children with
ADHD (Leibson et al., 2006). A similar pattern may not have emerged from the current
study for several reasons. In the current study parents reported the length of time their
children had been receiving medication for the treatment of ADHD symptoms and not the
length of time the child had been on the current medication treatment regimen. Leibson et
al. (2006) only included children treated with stimulant medication and reported on
medically attended injuries while the current study included children treated with
different medication regimens and examined the frequency of minor rather than
medically attended injuries. It may be that stimulant medication serves to mitigate risk for
medically attended but not minor injuries and additional research is necessary.

Compliance with medication treatment regimens was also unrelated to the
occurrence of injury in the current study. This may have been inﬂuenced by the fact that
the majority of parents reported relatively high levels of medication treatment integrity.
Previous research has suggested that children were more likely to incur injuries during
periods of time when they were not taking their medication (Thomas et al., 2004) or
receiving any form of treatment (Gering et al., 1998). In the current study, treatment
integrity was assessed on a weekly basis which precluded the examination of a direct

relationship between daily treatment compliance and injury occurrence. Consistent with

62

high levels of parent-reported treatment integrity, weekly monitoring of ADHD
symptoms revealed that levels of symptom severity were relatively stable and just below
the at-risk range. Therefore, it appears that the approaches utilized for the management
of the symptoms of ADHD among children in this sample resulted in consistent effects
across the 4-week period but did not result in a reduction of behavioral symptoms to a
normalized level. This parallels data from previous literature that stimulant medication
treatment effectively targets the core features of ADHD but does not result in a
normalization of behavior (Pelham et al., 2000) which may suggest the need for close
monitoring and titration of medication to achieve optimal treatment effects.
ADHD Symptomatology and Unintentional Injuries

The current study identiﬁed an association between parent-reported weekly
ADHD symptoms and minor unintentional injuries among children. For 3 of the 4 weeks
of the study, weekly injuries experienced by children were predicted by symptoms of
hyperactivity and/or attention problems. This is consistent with the theoretical
understanding of increased injury risk among children with ADHD which is thought to be
mediated through inattention, impulsivity, and hyperactivity that are the central clinical
features of the disorder (Pless, Taylor, & Arsenault, 1995). Speciﬁcally, increased
symptoms of hyperactivity predicted injuries during the third week of the study while
increased attention problems predicted injuries during the second and fourth weeks. It is
important to note that during the second and third weeks of the study, regression models
including both hyperactivity and attention problems as predictors reached statistical
signiﬁcance. However, neither factor independently contributed signiﬁcantly to the

models prior to the removal of the other factor. This suggests that the shared variance

63

among hyperactivity and attention problems may also be related to the occurrence of
minor unintentional injuries. When average symptom severity scores across the 4 weeks
were examined, measured levels of hyperactivity predicted the average number of weekly
injuries experienced by children.

One possible explanation as to why neither hyperactivity nor attention problems
predicted injuries during the ﬁrst week of the study centers on parent reporting of injury
data. Parents reported greater numbers of injuries during the ﬁrst week of the study than
they did during each of the subsequent weeks. This trend may have been inﬂuenced by
the fact that during the ﬁrst data collection period, parents were asked to report on the
number of minor injuries their children had experienced since birth and over the past 3
months in addition to the number of minor injuries experienced over the past 2 to 3 days.
Therefore, recall of injury may have been inﬂuenced by recall involving multiple periods
of time. Whereas each subsequent data collection point required parents to recall injuries
during a distinct 2 to 3 day period, the onset of which was marked by the end of a
previous reporting period.

The results of this study are consistent with recent literature supporting a
relationship between the behavioral symptoms associated with ADHD and childhood
unintentional injuries (Schwebel et al., 2004; Spinks et al., 2007). Speciﬁcally, Spinks
and colleagues (2007) reported that children with high hyperactivity scores were at
increased risk of all injuries in addition to medically attended injuries, and Schwebel and
colleagues (2004) found that hyperactivity was a strong predictor for parent-reported
medically attended injuries among young children. Additionally, others have reported

associations between vigilance deﬁcits and inattention and injury risk among children

64

(Bennett—Murphy et al., 2001; Pless et al., 1995). A notable distinction between these
studies and the current study; however, centers on the samples employed. While the
former studies included children who did not have a clinical diagnosis of ADHD, the
current study included children whose parents reported a diagnosis of ADHD. Thus,
hyperactivity and attention deﬁcits may have a differential impact on injury risk among
children with and without ADHD or children with clinical versus subclinical levels of
symptom severity.

Studies which have examined the relationship between ADHD and injury risk
have reported mixed results. For example, Bryne and colleagues (2003) reported that
preschoolers with an ADHD diagnosis did not sustain more injuries than control children
and DuPaul et al. (2001) found no differences in the number of injuries between 3
through 5 year old children with ADHD and normal controls. Conversely, Lahey and
colleagues (1998) reported that children aged 4 through 6 years who met criteria for
ADHD hyperactive-impulsive type or combined type were signiﬁcantly more likely than
controls to have experienced an unintentional injury. While the results from Lahey et al.
(1998) appear to point to the inﬂuence of symptoms hyperactivity-impulsivity on injury
risk among children with ADHD, the former studies only examined differences in
injuries between children with an ADHD diagnosis and controls and did not speciﬁcally
explore the impact of ADHD symptomatology on injury risk. As such, the relationship
between the behavioral symptoms of ADHD and injury risk among children with ADHD
has been poorly understood from an empirical basis. The current study contributes to the

existing literature by reporting that among children with an ADHD diagnosis, elevated

65

symptom severity appears to be a salient predictor of minor unintentional injuries when
the presence of comorbid symptoms is not considered.
Comorbid Symptomatology and Unintentional Injuries

While there is substantial evidence that hyperactive and inattentive behavior
patterns are related to increased injury risk among typically developing children
(Schwebel & Barton, 2006), researchers in the area of pediatric unintentional injury have
hypothesized that children with externalizing behavior disorders are at increased risk of
injury not because of hyperactive or inattentive symptoms, but instead because of their
oppositional, deﬁant and disruptive behavior (Davidson et al., 1988; Schwebel et al.,
2007). The results of the current study provide partial support for this hypothesis in that
symptoms associated with ADHD did not predict the occurrence of minor unintentional
injuries after controlling for the presence of comorbid symptoms associated with conduct
disorder (CD). However, inconsistent with the aforementioned hypothesis, symptoms of
oppositional deﬁant disorder (ODD) did not contribute to injury risk in the current study.
Symptoms of CD reported by parents at the beginning of the study accounted for half of
the variance in minor injuries experienced by children during the 4-week study period.

This ﬁnding, which illuminates the importance of examining comorbid behaviors,
is consistent with those from two recent studies which explored injury risk among
children with a clinical diagnosis of ADHD who also had diagnoses or symptoms of
comorbid externalizing behavior disorders (Schwebel et al., 2007; Schwebel et al., 2006).
Among a sample of children with ADHD, Schwebel and colleagues (2007) reported that
symptoms of ODD and CD rather than symptoms of ADHD were signiﬁcantly related to

injuries. The researchers developed an ODD/CD composite which was comprised of

66

behaviors related to violations of rules, intentional aggression, noncompliance, and
intentional property destruction. Only intentional aggression and violations of rules were
signiﬁcantly related to injury occurrence. Given this methodological approach, it remains
unclear how symptoms of ODD and CD are differentially related to injury occurrence.
The current study reported that symptoms speciﬁcally related to CD and not necessarily
ODD as measured by a standardized behavior rating scale predicted injury in children
diagnosed with ADHD.

Schwebel and colleagues (2006) reported that young children with ODD were at
increased risk for injury relative to children with ODD and comorbid ADHD, suggesting
that the presence of ADHD did not increase injury risk. These researchers did not;
however, examine the inﬂuence of symptoms of CD on injury risk among children with
ADHD. Exploratory analyses in the current study revealed that symptoms of ODD also
predicted injury occurrence above and beyond ADHD symptoms; however, this was only
true when symptoms of CD were not included in the analysis. When symptoms
associated with CD were included in the regression model, symptoms of ODD and
ADHD no longer signiﬁcantly predicted injury. While the current study provides
additional support for the hypothesis that comorbid disruptive behaviors inﬂuence injury
occurrence among children with ADHD, it also extends the previous literature in
recognizing the unique contribution of symptoms associated with CD (e. g., aggression
toward others, serious violations of rules) rather than ODD (e.g., refusing to go along
with adult requests, deliberately annoying others).

One reason children with disruptive patterns of behavior may experience greater

frequency of injury is because they intentionally violate rules and defy authority.

67

Schwebel and Gaines (2007) outlined an argument suggesting that children who are only
hyperactive or inattentive may place themselves in potentially dangerous situations. But,
if these children are appropriately supervised by an adult who warns the child to stop
behaving in a dangerous manner, an injury may be averted. If the child has comorbid
deﬁant and disruptive behavior problems; however, he or she may not heed the warning
to stop a dangerous behavior and may suffer an injury (Schwebel and Gaines, 2007).
Consistent with the argument, results from this study suggest that symptoms such as
hyperactivity and poor attentional capacity were not the factors that placed children with
ADHD at increased risk for injury. Rather children who had symptoms of comorbid
behavior disorders were shown to experience more injuries.
Medically Attended Unintentional Injuries

The ﬁnal aspect of this study considered the relationships between minor and
medically attended unintentional injuries as well as demographic factors related to the
occurrence of a medically attended injury. Several positive correlations were reported
between child injury history variables and minor injuries experienced during the study.
The total number of minor injuries experienced since birth was positively correlated with
all other injury measures, with the exception of recent medically attended injuries. In
general these ﬁndings are consistent with previous research among typically developing
children which has reported a positive association between minor and severe injuries
(Morrongiello et al., 2004). No relationships were found between medically attended
injuries experienced during the previous 3 months and any other injury variable. This
may be due to the extremely low number of children who had experienced a medically

attended injury during the 3 month interval. This is consistent with injury morbidity and

68

mortality statistics which suggest that medically attended injuries are relatively low base
rate events (Peterson et al., 1996; Pless et al., 1995).

When considering injury history variables, the only type of previous injury to
predict minor injuries experienced during the 4-week study period was parent-reported
minor injuries since birth. Among typically developing children, Jaquess and Finney
(1994) reported that the occurrence of a severe injury was associated with subsequent
minor injuries and it was hypothesized that the nature of this relationship would hold true
for children with ADHD; however, this relationship was not found within the current
sample. It is possible that the occurrence of a medically attended injury in a child with
ADHD resulted in the initiation or alteration of treatment regimen which may have
inﬂuenced the occurrence of subsequent injuries.

Binary logistic regression results did suggest a relationship between the number
of minor injuries experienced since birth and the likelihood of children having
experienced a medically attended injury. The odds that a child had ever experienced a
medically attended injury increased slightly for each additional minor injury reported.
This ﬁnding makes sense given that minor injuries have the potential to be serious.
Therefore, children who experience more minor injuries may be increasingly likely to
have one of these injury episodes result in the need for medical attention. The likelihood
that a child had ever experienced a medically attended injury was greater for children
who were younger in age. This result may seem unexpected given that older children
simply by nature of their age have had more time to experience injury. However, this
ﬁnding is consistent with literature suggesting that young children are at increased risk

for injury relative to their older counterparts. Additionally, this ﬁnding suggests that

69

children diagnosed with ADHD at a young age may be especially vulnerable for
experiencing a medically attended injury. The number of children living in the household
was the variable most strongly associated with the likelihood of children having
experienced a medically attended injury. This variable was inversely related to injury
such that as the number of children living in the household decreased the likelihood of a
child having experienced a medically attended injury increased. Given that poor parental
supervision, which is often associated with an increased number of children in the
household, is a risk factor for childhood injury (Morrongiello et a1, 2006; Schwebel et al.,
2006), one might have anticipated a ﬁnding in the opposite direction. However, it is
important to note the household size was assessed after the occurrence of the medically
attended injury. Therefore, household size may indirectly be inﬂuenced by the
occurrence of a medically attended injury rather than the number of children in the
household inﬂuencing the likelihood that a child had a history of a medically attended
injury.
Conclusions

The results from this study seem to support ﬁndings from the literature that
children with ADHD have higher levels of injury compared to other children their age.
While a control group was not employed in the current study, the number of weekly
injuries reported in this study was greater than the average number of injuries reported
among a group of children with ADHD during a summer camp (Schwebel et al., 2007).
The design of the study by Schwebel and colleagues (2007) permitted a comparison of
injury rate among their sample and injury rates reported in the literature among typically

developing children. Speciﬁcally, the injury rate among the children with ADHD was

70

comparable or slightly higher than that of nondisordered children who were engaged in
high—contact athletic activities (Schwebel et al., 2007). This suggests that the children
enrolled in the current study demonstrated higher rates of injury than what would be
expected to be observed among nondisordered children.

Although the literature on unintentional injury has suggested an association
between disruptive behaviors and injury risk among children with ADHD, this claim has
been largely unsubstantiated empirically. Findings from the current study parallel those
from two recent studies (Schwebel et al., 2006; Schwebel et al., 2007) and suggest that
symptoms of comorbid externalizing behavior disorders are associated with increased
injury risk among children with ADHD. However, the majority of previous research has
examined the relationships between injury and clinical diagnoses. This study extends the
current line of research through its examination of the association between symptom
severity and injury. While previous literature and theory have implicated the role of
disruptive behaviors commonly associated with diagnoses of CD and ODD with injury
risk, this study suggests that symptoms of CD (e.g., aggression toward others, serious
violations of rules) are the strongest predictor of the occurrence of minor unintentional
injuries among children with ADHD. While the behavioral symptoms of hyperactivity
and inattention predicted the occurrence of weekly minor injuries in the current study,
symptoms of ADHD were not predictive of minor unintentional injuries after controlling
for the presence of behaviors associated with CD. Although hyperactivity and inattention
have consistently been associated with injury risk among typically developing children, it
seems to be the associated disruptive behaviors often present in children with ADHD that

make this group of children increasingly likely to experience injury.

71

The results of this study cautiously support that no differences in injury existed
among children with ADHD treated with extended release methylphenidate and extended
release mixed amphetamine salts. Moreover, no differences in ADHD or comorbid
symptom severity were found between these treatment groups. Previous literature has
supported the later ﬁnding in demonstrating similar treatment effects of these different
psychostimulants in reducing ADHD symptom severity (Plizska et al., 2001). However,
data from this study provide a preliminary indication of the equivalence of these different
extended release psychostimulants on injury rate. Observed group differences, especially
with such a small sample size, would be concerning and have substantial implications for
treatment.

Clinical Implications

Several implications related to the prevention of childhood unintentional injuries
can be gleaned from the results of this study. Perhaps most importantly is the need for
close supervision and monitoring of children with ADHD who also exhibit deﬁant,
destructive, and disruptive patterns of behavior. The results of this study suggest that
children with ADHD who also exhibit comorbid behavioral difﬁculties are more likely to
incur minor unintentional injuries than children with ADHD who do not have associated
behavioral difﬁculties. While this study did not speciﬁcally examine the relationship
between supervision and injury, previous research has reported that among typically
developing children poor parental supervision is related to increased injury risk
(Morrongiello et al., 2006), and among hyperactive children parental supervision has
been identiﬁed as a protective factor for injury risk. Among children with ADHD poor

parental supervision has been associated with increased risk taking behaviors especially

72

for children with ADHD who also presented with symptoms of ODD and CD (Schwebel
et al., 2006). Taken together, these ﬁndings indicate that close supervision and
monitoring of children with ADHD and comorbid behavioral difﬁculties are essential as
these children are not only more likely to engage in risky behavior under conditions of
poor supervision but also are at increased risk for experiencing unintentional injury. In
light of the clinical signiﬁcance of the frequency of minor injuries during a given week,
children with ADHD without clinical diagnoses of ODD and CD warrant close
monitoring. Strategies such as titrating medications or the implementation of parent
training programs as a means to successfully reduce symptoms of associated behavioral
disorders will be important in order to effectively mitigate injury risk among children
with ADHD. Medication treatment and behavioral parent training have been identiﬁed as
evidenced-based interventions for the treatment of childhood behavior disorders and the
targeted use of such treatments may serve to reduce injury in this at-risk population
(APA, 2007).

Additionally, injury prevention programs and efforts should be targeted toward
children with ADHD who also exhibit deﬁant and disruptive patterns of behavior. In
order for targeted prevention efforts to be implemented, the results of this study speak to
the importance of monitoring symptom severity among children with ADHD who are and
are not treated pharmacologically. In order for symptom monitoring to inform injury
prevention efforts, such monitoring will need to involve measuring not only symptoms of
ADHD but also symptoms of associated behavioral disorders. This will likely necessitate
open lines of communication between physicians, parents, and school personnel.

Effective school-based medication monitoring involves several important steps and

73

school psychologists are often well positioned to contribute to these practices (Carlson,
2008; DuPaul and Carlson, 2005). Speciﬁc areas of functioning to assess must be
identiﬁed and the use of objective, psychometrically sound measures such as behavioral
rating scales and direct observations are critical (DuPaul & Carlson). When monitoring
medication effectiveness it is imperative to simultaneously monitor medication side
effects as these may have deleterious effects on child behavior (Carlson). School
psychologists are uniquely positioned to collect, interpret, and share data about symptom
severity and medication effects with families and physicians and decisions made as a
result of these practices may serve to reduce injury risk among children with ADHD.

Moreover, schools provide an ideal context for the implementation of universal
and targeted injury prevention programs. School-based prevention programs have the
potential to reach a large number of children in a cost-effective manner. Schwebel and
colleagues (2006) demonstrated that school-based programs are effective in reducing
risky playground behaviors among young children by increasing supervision and
monitoring of school staff. The basic line of reasoning holds that the reduction of
dangerous behavior should subsequently reduce injury risk. Importantly, school-based
programs have the beneﬁt of reaching children who are identiﬁed as at-risk in addition to
children who may not exhibit the prototypic behavioral proﬁle of an at-risk child, yet
may be an increased risk for injury because of other variables (e. g., deﬁcits in executive
functioning, physical disability).
Future Research

The results of this study support recent data which have identiﬁed the role of

associated behavioral difﬁculties as an important mechanism of injury risk among

74

children with ADHD (Schwebel et al., 2007). It will be important for researchers to
continue to delineate the contribution of multiple behavioral symptoms among clinical
samples on pediatric unintentional injury risk. Moreover, future research should examine
the extent to which injury risk among children with externalizing behavior disorders is
mediated by deﬁcits in executive functioning, which are consistently linked with the core
behavioral features of ADHD (Stefanatos & Baron, 2007).

Theoretical and empirical works have provided support for the idea that stimulant
medication treatment may mitigate unintentional injury risk among children with ADHD
(Rapport et al., 2001; Lage & Hwang, 2004). Speciﬁcally, stimulant medication treatment
has been implicated in reducing risk of medically attended injuries (Lage & Hwang,
2004; Pastor & Reuben, 2006) among children with ADHD relative to children with
ADHD who were not treated pharmacologically. The extent to which medication
treatment may normalize rates of injury occurrence among children with ADHD relative
to typically developing children remains unclear. Given the increased utilization of
extended release medications (Castle, 2007), future research examining the differential
impact of different extended release medication formulations on injury risk is warranted.
Although the current study did not report differences between two commonly prescribed
extended release medications, additional research comparing the effects of extended
release methylphenidate and extended release mixed amphetamine salts is necessary
given the consistent differences reported within the adolescent driving literature (Cox et
al., 2006; 2008). Previous research has demonstrated differences between immediate
release and extended release psychostimulant medications with respect to the occurrence

of medically attended injuries (Kemner & Lage, 2006; Lage & Hwang, 2004). It will be

75

important for future research to examine the differential impact of short-acting and long-
acting medications on minor injury risk among children with ADHD. Finally, with
respect to medication treatment, research should continue to explore the role of the
rebound effect and how such behavioral deterioration may be related to injury occurrence
in children treated pharmacologically for ADHD.
Limitations

Given the nature of the study design, a major limitation of the current study
centered on lack of random assignment to medication treatment condition. More
importantly, between group analyses were limited with respect to sample size. The power
to detect group differences was extremely low and it is unclear if group differences failed
to emerge because there were actually no group differences in injury rates or if there was
simply insufﬁcient power to detect such differences. As such, these ﬁndings cannot be
considered conclusive for this sample of participants or generalized beyond the current
sample. Another limitation centers on the identiﬁcation of children with ADHD.
Participants were included in the study per parent report of a physician diagnosis of
ADHD or if they met diagnostic criteria based scores derived from a standardized rating
scale. As such, many children did not evidence clinically signiﬁcant symptoms upon
study enrollment. This suggests that the medication treatments might have been working
effectively to reduce the core behavioral symptoms of ADHD as children with elevated
symptoms may have been in need of a medication adjustment. It is unclear how this may
have inﬂuenced injury occurrence across the 4 week study period. However, this does
suggest the need to monitor injury rates both before and after the initiation of medication

treatment to more clearly delineate the role of medication in mitigating injury risk among

76

children with ADHD. Future medication trials should measure injury occurrence as a
peripheral symptom that would be ideal to have altered by medication or any alternative
intervention for ADHD.

Additionally, this study relied exclusively on parent report which is limited
primarily in terms of reliability. One possible alternative to parent report of minor injury
centers on monitoring of injury by professional caregivers such as camp counselors or
school nurses. Schwebel and colleagues (2007) utilized reports from summer camp
counselors to record the occurrence of minor injuries. The current study utilized bi-
weekly phone calls to monitor injury, but others have had parents report injury through
the completion of daily phone calls or daily injury logs (Bennett-Murphy et al, 2001;
Peterson et al., 2002). This study also relied on parent reports of symptom severity.
Alternative methods of corroborating such data include direct observations in classrooms
or home settings as well as the use of reports from other individuals such as school
teachers. Finally, this study did not include systematic measures of parental supervision
which has been associated with injury risk among children with externalizing behavior
disorders. Previous studies have attempted to measure this variable through direction
observations of parent-child interactions in clinical settings (Schwebel et al., 2004) or
homes (Morrongiello et al., 2004) as well as through parent report of amount and quality

of supervision provided (Morrongiello et al., 2006).

77

APPENDICIES

78

APPENDIX A

Table 1. Demographic characteristics (N = 31)

 

 

Variable N (%)
Child Gender

Male 24 (77.4)

Female 7 (22.6)
Child Ethnicity

Caucasian 27 (87.1)

African-American 1 (3.2)

Other 3 (9.7)
Child Age

5-8 years 11 (35.5)

9-12 years 20 (64.5)
Parent Education

High School (GED) 9 (29.0)

Some College 9 (29.0)

College Graduate 8 (25.8)

Post-Graduate 5 (16.1)
Parent Martial Status

Married 20 (64.5)

Single 2 (6.5)

Divorced 4 (12.9)

Widowed 2 (6.5)

Living with partner 3 (12.9)

 

79

APPENDIX B

Table 2. Medication Treatment (N = 28)

 

 

Medication N (%)

Drug Name
Adderall 10 (32.3)
Concerta 7 (22.6)
Focalin 2 (6.5)
Daytrana 2 (6.5)
Ritalin 3 (9.7)
Metadate 1 (3.2)
Strattera 2 (6.5)
Vyvanse 1 (3.2)
Tenex l (3.2)

 

80

APPENDIX C

Table 3. Clinical symptoms: CBCL (N = 31)

 

 

Scale Mean (SD)
Anxious/depressed 62.29 (8.17)
Withdrawn/depressed 60.35 (8.56)
Somatic complaints 59.13 (7.52)
Social problems* 62.48 (8.41)
Thought Problems* 64.31 (7.41)
Attention problems 67.90 (9.46)
Rule-breaking behavior* 59.83 (8.65)
Aggressive behavior 61.61 (9.21)
Intemalizing problems 61.32 (9.08)

Extemalizing problems

60.10 (10.89)

Total problems 63.45 (9.13)
Affective problems 63.45 (8.46)
Anxiety problems 60.39 (7.20)
Somatic problems 59.66 (9.16)
Attention-deﬁcit/hyperactivity problems: DSM- 65.45 (8.02)
oriented

Oppositional deﬁant problems: DSM-oriented 59.81 (7.08)
Conduct problems: DSM-oriented* 61.72 (9.33)

 

* Scores based on age and gender norms, (M=50, SD=10)

** Composite score not available for children under 6 years of age (N = 29)

81

APPENDIX D

Table 4. Clinical symptoms: BASC-Monitor* (N = 31)

 

 

Scale Mean (SD)

Hyperactivity 58.96 (1 1.18)
Week 1 59.48 (11.58)
Week 2 59.22 (12.14)
Week 3 57.55 (12.49)
Week 4 59.58 (12.58)

Attention problems 59.70 (9.75)
Week 1 57.45 (10.48)
Week2 61.61 (11.71)
Week 3 59.74 (9.79)
Week 4 59.58 (12.58)

 

* Scores based on age and gender norms, (M=50, SD=10)

82

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83

APPENDIX F

Table 6. Relationship between weekly ADHD symptom severity and unintentional

injuries: Regression Models

 

 

Dependent Variable Predictor Excluded R2 Beta p-value
Variable

Week 2 Injuries Attention Problems .146 .383 .034
Hyperactivity .038 .884

Week 3 Injuries Hyperactivity .208 .456 .010
Attention .265 .173
Problems

Week 4 Injuries Attention Problems .217 .466 .008
Hyperactivity .162 .43 8

Mean Injuries Mean Hyperactivity .162 .403 .025
Mean Attention .184 .421
Problems

 

84

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86

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