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 wer e interviewed at baseline, six months (49%), and 12 months (57%). At baseli ne, exchangers were less likely than nonexchangers to share syringes (21% v s. 37%), have multiple sharing partners (7% vs, 19%), and reuse their syrin ges (73% vs. 90%). These differences persisted in multivariate analysis adj usting for gender, age, race, education, and injection frequency. For the s ubset of participants who provided data at all three time points (n=101), r ates 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.