Social norms, social networks, and HIV risk behavior among injection drug users.

Social network structure and norms are linked to HIV risk behavior. However little is known about the gradient of norm of HIV risk that exists among social networks. We examined the association between injection risk network structure and HIV risk norms among 818 injection drug users (IDUs). IDUs were categorized into four distinct groups based on their risk behaviors with their drug networks: no network members with whom they shared cookers or needles, only cooker-sharing member, one needle-sharing member, and multiple needle-sharing members. The riskiest group, networks of multiple needle sharers, was more likely to endorse both risky needle-sharing and sex norms. Networks of only cooker sharers were less likely to endorse high-risk norms, as compared to the networks with no sharing. There were also differences based on gender. Future HIV prevention interventions for IDUs should target both injection and sex risk norms, particularly among IDUs in the multiple needle-sharing networks.