Long-term effects of syringe exchange on risk behavior and HIV prevention.

The purpose of this study was to assess stability of population-level injection risk behavior over time among participants in a syringe exchange program and compare factors affecting syringe sharing at two points in time. Participants of the Tacoma Syringe Exchange Program were interviewed in 1997 and 2001 using audio computer assisted self-interviewing technology. In each wave of data collection, a random cross section of participants was recruited and interviewed, with no attempt made to follow respondents over time. Rates of injection risk behavior remained stable across the 4-year period, despite increases in factors associated with syringe sharing. Homelessness, rates of depression symptoms, and injection of amphetamines all increased from 1997 to 2001. The central factors associated with syringe sharing in both 1997 and 2001 were depression symptoms and the interaction of younger age with amphetamine injection. The data indicate that the exchange has been able to stabilize risk among a high-risk population for a substantial period of time. This study confirms previous findings that SEPs can play a significant role in the prevention of HIV in marginal and impoverished communities in the United States.