Background: AIDS (Acquired immune deficiency syndrome) is a global public health issue affecting millions of individuals. HIV (Human immunodeficiency virus) infected individuals commonly acquire hepatitis B and C viral infections through shared transmission routes. In order to evaluate the effect of hepatitis co-infection on HIV infected individual, the objectives of our study were ; 1) to investigate the geographic distribution of HIV-hepatitis co-infection, 2) to estimate the prevalence of hepatitis co-infection and associated factors, and 3) to estimate the mortality and identify factors associated with mortality; among HIV-hepatitis co-infected individuals residing in Michigan during the years 2006 to 2009.Methods : We conducted a retrospective cohort study from January 1, 2006 to December 31, 2009 using data from the Michigan Department of Community Health. HIV infected individuals were matched to hepatitis B and C cases for the same time period by establishing a record linkage. Spatial, logistic and survival regression analyses were performed on the data to evaluate the objectives of the study.Results : The Bernoulli cluster analysis of HIV-hepatitis B or C co-infection identified a most likely cluster with a significant relative risk (RR = 1.75) in the northeast Lower and Upper peninsulas. Poisson cluster analysis identified a most likely cluster with a significant RR of 2.93 in the northwest Lower Peninsula. Multivariable logistic regression analysis revealed a significant association between co-infection and being male and of Black race (Odds Ratio (OR) =2.0, 95% Confidence Interval (CI): 1.2-3.6) and male and of Other race (OR=3.5, 95% CI: 1.7-7.0) as compared to White race. Co-infection was associated with risk categories of blood products, IDU (Injecting drug user) and MSM/IDU (Males having sex with males) and two interactions; sex and current HIV status and current HIV status and age at HIV diagnosis. The final Cox regression model indicated a decreased survival; among individuals of Other (Hazards Ratio (HR) =2.2, 95% CI: 1.4-3.2) and Black (HR=1.3, 95% CI: 1.1-1.6) races compared to White race, and IDU, MSM/IDU, individuals with undetermined risk, heterosexual practices, and older age at HIV diagnosis in addition to an interaction between current HIV status and co-infection status.Conclusions: This study identified localized clusters of HIV-hepatitis co-infection in counties outside of Michigan's urban areas where HIV is more prevalent. Overlapping counties indicate ‘`hotspots'’ for co-infection in the Upper Peninsula and upper portion of the Lower Peninsula. The relatively high prevalence of co-infections and mortality suggests the existence of a continuing public health problem. Our study aimed to address the changing epidemiology of HIV-hepatitis co-infections in order to implement preventive measures and interventions to reduce prevalence and mortality among the HIV infected individuals.
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