Objective: To determine factors associated with syringe and injection supply sharing among injection drug users (IDUs) in a community with an illegal underground syringe exchange program (SEP).
Methods: From 1992 to 1995, semiannual cross-sectional samples of IDUs were recruited in Oakland, California. To account for multiple observations from the same individual, we used general estimating equations with logit transformations to determine factors associated with sharing syringes and other injection supplies.
Results: 1304 IDUs were interviewed; 684 (53%) returned for more than one interview. 2830 interviews were available for analysis. SEP use increased and syringe and supply sharing declined from 1992 to 1995 among study participants. In multivariate analysis, SEP users were less likely to share syringes than non-SEP users (adjusted odds ratio [AOR] = 0.57; 95% confidence interval [CI] = 0.46-0.72). SEP use was not significantly associated with the sharing of injection supplies (AOR = 0.85; 95% CI = 0.68-1.07). Syringe sharing and injection supply sharing were significantly less likely to occur among African American and HIV-positive IDUs.
Conclusions: These data suggest that illegal SEPs can be effective HIV prevention programs. Lower rates of syringe-based risk behaviors among African American and HIV-positive IDUs are encouraging.