Latent classes of heroin and cocaine users predict unique HIV/HCV risk factors

Background: Patterns of heroin and cocaine use vary and may be associated with unique risk factors for bloodborne infections. Methods: Latent class analysis identified sub-populations of 552 heroin and cocaine users in Baltimore, Maryland. Using latent class regression, these classes were analyzed for associations with demographic characteristics, risky behaviors, Hepatitis C, and HIV. Results: Three classes were found: Crack/Nasal-Heroin users (43.5%), Polysubstance users (34.8%), and Heroin Injectors (21.8%). Compared to Polysubstance users, Crack/Nasal-Heroin users were almost 7 times more likely to identify as Black (OR = 6.97, 95% CI = 4.35-11.2). Sharing needles was over 2.5 times more likely among Polysubstance users than among Heroin Injectors (OR = 2.66, 95% CI = 1.49-4.75). Crack/Nasal-Heroin users were 2.5 times more likely than Polysubstance users to exchange drugs for sex (OR = 2.50, 95% CI = 1.22-5.13). Crack/Nasal-Heroin users were less likely than Heroin Injectors to have Hepatitis C (OR = 0.10, 95% CI = 0.06-0.18), but no significant differences were found for HIV. Conclusions: Subpopulations of cocaine and heroin users differed in demographic classifications, HIV-risk behaviors, and Hepatitis C infection. All subpopulations included substantial numbers of HIV-positive individuals. Findings provide further evidence that non-injection drug users face significant infectious disease risk.