Drug sharing among heroin networks: implications for HIV and hepatitis B and C prevention.

Qualitative and quantitative findings from the baseline survey of a longitudinal, socially-focused blood-borne disease intervention study among 611 heroin IDU in Denver indicate that high risk injection practices-the sharing of contaminated drug solution in particular-often occur as a consequence of how heroin is obtained, the quantity obtained and the setting where it is injected. Contamination occurs if a contaminated syringe is used to liquefy and apportion the shared drug. In our cohort of 304 heroin injecting networks there was at least one member who, when asked to describe their last injection, reported dividing the drug as a liquid (82%), using a reservoir of water that syringes had been rinsed in to mix drugs (67%), using a common cooker (86%)-a proxy for drug sharing-and beating a shared cotton filter (58%). In contrast, only 22% reported syringe sharing. Variables associated with various injection practices included location of the last injection episode, quantity of drug injected, dope sickness, and years injecting. When compared to those who injected in a safe setting, those in an unsafe location had almost three times the odds (OR = 2.9; 95% CI: 1.9, 4.6) of being part of an injection episode where there was cooker sharing; and the smaller the quantity of heroin (< or =1/4 gram v. > 1/4 gram) present at the episode, the greater the odds that cooker sharing occurred (OR = 1.8; 95% CI: 1.2, 2.6). Use of a used, unbleached syringe to prepare shared drugs had twice the odds of occurring in "unsafe" v. safe settings (OR = 2.2; 95% CI: 1.3, 4.0) and in episodes in which a participant was dopesick (OR = 2.1; 95% CI: 1.2, 3.6). In summary, risky injection practices occur within an injection process that is, in part, a response to a structurally imposed risk environment. Lessening the blood-borne disease risks embedded within this process requires interventions designed to mitigate the environmental factors that influence it, including syringe accessibility, law enforcement strategies and the settings where IDU inject drugs.