Adolescent girls and young women (AGYW) in South Africa experience contextual barriers to HIV risk reduction including incomplete schooling, unintended pregnancy, substance use, and gender-based violence. A cluster randomised trial in Cape Town allocated 24 Black and Coloured communities to a gender-focused HIV risk-reduction intervention or HIV testing, with 500 AGYW total enrolled. We evaluated intervention efficacy by comparing mean differences overall, by community population group (Black and Coloured) and among those with structural barriers based on neighbourhood, education, and employment (n = 406). Both arms reported reductions in alcohol, cannabis, and condomless sex, with no intervention efficacy overall. Among AGYW with barriers, intervention participants reported fewer days of methamphetamine use at 6 months (t(210) = 2·08, p = ·04). In population group analysis, we found intervention effects on alcohol and sexual communication. Intervention participants in Black communities had fewer days of alcohol use at 12 months (t(136) = 2·10, p = ·04). Sexual discussion (t(147) = -2·47, p = ·02) and condom negotiation (t(146) = -2·51, p = ·01) increased for intervention participants at 12 months in Coloured communities. Gender-focused interventions must address population group differences and intersecting barriers to decrease substance use and increase education, skills, and sexual health protection.
Keywords: Sexual negotiation; condom use; education; heavy alcohol use; methamphetamine use.