Baseline prevalence of different substances.

Adolescent girls and young women (AGYW) in sub-Saharan Africa are at substantial risk of HIV acquisition and could benefit from oral pre-exposure prophylaxis (PrEP) for HIV prevention. Substance use may result in poor adherence, diminishing PrEP effectiveness. The effects of substance use on PrEP adherence in AGYW within the African context have not been extensively studied. We sought to determine the prevalence of substance use and its association with PrEP adherence in AGYW enrolled in an HIV prevention trial. The HIV Prevention Trials Network (HPTN) 082 study enrolled healthy, HIV-negative, sexually active young women (16–25 years) from Cape Town, Johannesburg, South Africa, and Harare, Zimbabwe, between October 2016–2018. Participants were offered oral PrEP. Data on hazardous drinking was collected using the AUDIT-C questionnaire and defined as having an AUDIT-C score ≥3. Data on substance use was collected using the abridged ASSIST questionnaire, with responses categorized as 0 (never used a substance) and 1 (ever substance use). Tenofovir-diphosphate (TFV-DP) levels in dried blood spots at weeks 13, 26, and 52 were used to measure PrEP adherence. Low adherence was defined as TFV-DP concentration