Methadone maintenance and needle/syringe sharing.

Drug users who inject drugs while in treatment share needles/syringes less often than users not in treatment. This relationship may reflect treatment processes, such as cognitive or normative change, by which treatment clients are influenced to lower their HIV infection risk. However, reduced needle/syringe sharing among treatment clients may instead be simply a collateral result of reduced injection frequency. In this sample of injection drug users, those who continued to inject while in methadone maintenance treatment reported less sharing than users not in methadone maintenance. This relationship persisted after injection frequency and drug-user background characteristics were controlled. Efforts to identify explanatory treatment processes were, however, not successful.