The dynamic relationship between social norms and behaviors: the results of an HIV prevention network intervention for injection drug users

Aims Social norms are a key source of influence on health behaviors. This study examined changes in social norms and relationships between HIV injection risk behaviors and social norms among injection drug users (IDUs) involved in an experimental intervention. Design Randomized clinical trial. Setting An HIV Prevention Trials Network study, Philadelphia, USA. Participants IDUs, called indexes, and their social network members, who were drug or sex partners, were recruited for an HIV prevention intervention and followed for up to 30 months (n = 652). Indexes were randomized into a peer education intervention or control condition. Measurements Outcomes of injection-related HIV risk behaviors (sharing needles, sharing cookers, sharing cotton, front-/back-loading) were measured every 6 months and the social norms of these four risk behaviors were assessed every 12 months. Findings There was a statistically significant intervention effect on all four social norms of injection behaviors, with participants in the intervention reporting less risky social norms compared with controls (changes in mean score: needles, −0.24, P = 0.007; cookers, −0.33, P = .004; cottons, −0.28, P = .0165; front-/back-loading, −0.23, P = .002). There was also a statistically significant bidirectional association with social norms predicting injection risk behaviors at the next assessment and risk behaviors predicting social norms at the subsequent visit. Conclusions Through social network interventions it is feasible to change both injection risk behaviors and associated social norms. However, it is critical that social network interventions focus on publically highlighting behavior changes, as changing social norms without awareness of behaviors change may lead to relapse of risk behaviors.