Selective risk taking among needle exchange participants: implications for supplemental interventions.

OBJECTIVES: This study characterized social network context of HIV risk behavior among injection drug users who participated in a needle exchange program.
METHODS: Interviews were conducted with 1184 injection drug users at the Baltimore Needle Exchange Program enrolled in an evaluation cohort. Analysis consisted of multiple logistic regression with statistical adjustment for the interdependence of observations.
RESULTS: Of the 203 (17.1%) injection drug users who reported using a syringe after someone else, 78.3% reported sharing with close friends, and the adjusted odds ratio of any sharing and sharing with close friends was 30.9. Injection drug users were more likely to report sharing with a strong-tie close friend (adjusted odds ratio = 1.52) and less likely to report sharing with other close friends if those friends were weak ties and new to their network. Friendship ties were not stable, with fewer than 30% of the friends being repeat nominations.
CONCLUSIONS: These data show that many injection drug users engage in selective risk taking that may minimize their disease risk exposure in the short term. The turnover in networks, however, suggests that programs need to emphasize the importance of exclusive use.