Rates of bacterial sexually transmitted infections (STIs) and substance use–related harms have risen sharply in the United States, yet little is known about whether drug treatment affects STI risk among people who use drugs. We analyzed prospective data from 2142 participants who reported illicit drug use at baseline in Project AWARE recruited from 9 STI clinics nationwide. We examined associations between self-reported drug treatment in the past 6 months at baseline and biologically confirmed incident STI at 6-month follow-up, overall and by gender, using inverse probability of treatment weighting to estimate average treatment effects (ATE) and average treatment effects among the treated (ATT). At baseline, 14% reported drug treatment. In unadjusted models, drug treatment was associated with higher STI risk (RR = 1.43, 95% CI: 1.09, 1.88), driven by laboratory-identified infections. After weighting, the ATE was attenuated (RR = 1.37, 95% CI: 0.91, 2.07) and the ATT was null. Gender-stratified analyses suggested elevated STI risk among women in unadjusted models, but weighted estimates were nonsignificant, although clinically diagnosed STIs were less common among women in drug treatment. Findings indicate complex, gender-specific relationships between drug treatment and STI risk and underscore the need for integrated, gender-responsive STI prevention within drug treatment settings.
Drug treatment and incident sexually transmitted infections among people who use drugs: A prospective analysis of gender differences
American Journal of Epidemiology [Epub 2026 Jun 1]. doi: 10.1093/aje/kwag111.