Socio-behavioral and geographic correlates of prevalent hepatitis C virus infection among young injection drug users in metropolitan Baltimore and Chicago.

BACKGROUND: Hepatitis C virus (HCV) infection prevalence among young injection drug users (IDUs) differs substantially between cities in the United States (U.S.).

METHODS: Between 2002 and 2004, IDUs aged 15-30 were recruited for the Third Collaborative Injection Drug User Study in five U.S. cities using respondent-driven methods. Our cross-sectional study examined correlates and geographic distribution of prevalent HCV infection (HCV+) from the Baltimore (n=736) and Chicago (n=586) study sites. We evaluated baseline socio-demographic and behavioral data collected from computer-assisted self-interviews and serological antibody testing for human immunodeficiency virus (HIV) and hepatitis A, B, and C.

RESULTS: HCV prevalence was 53.0% in Baltimore and 13.7% in Chicago (p<0.0001). Baltimore compared to Chicago participants were significantly (p<0.05) more likely to be older, co-infected with HIV and other hepatitis viruses, reside in an urban area, inject primarily cocaine, inject in public settings, inject with used syringes and paraphernalia, and have been injecting longer; they were less likely to utilize syringe exchange programs. However, after accounting for socio-demographic and behavioral risk factors in multivariable logistic regression, city was the strongest predictor of HCV prevalence (Baltimore versus Chicago adjusted odds ratio=3.5 [95% confidence interval, 2.2-5.6]). Geospatial analyses showed that almost half of all HCV+ participants in Baltimore resided within a 5-mile urban area, while Chicago participants were dispersed across the metropolitan area.

CONCLUSIONS: The disparate HCV prevalence between the two cities is only partially explained by individual-level factors. Future studies should examine the network configurations and injection partners' characteristics of young IDUs.