A Cohort Study of Syringe Exchangers and Nonexchangers in San Francisco

This paper presents a cohort study of injection drug users (n=229) who did and did not use syringe exchange in San Francisco in 1993. Participants were interviewed at baseline, six months (49%), and 12 months (57%). At baseline, exchangers were less likely than nonexchangers to share syringes (21% vs. 37%), have multiple sharing partners (7% vs. 19%), and reuse their syringes (73% vs. 90%). These differences persisted in multivariate analysis adjusting for gender, age, race, education, and injection frequency. For the subset of participants who provided data at all three time points (n=101), rates of syringe sharing, syringe reuse, and indirect sharing decreased over time for both exchangers and nonexchangers. Nonetheless, levels of indirect sharing remained high among exchangers in this study (>45%) and decreased significantly less than nonexchanger levels over time. The implications of these Findings for syringe exchange programs and research are discussed.