Polysubstance Use Profiles and HIV Viremia in a South African Cohort of Female Sex Workers: A Latent Class Analysis

Abstract

Background: Given intersecting social and structural factors, female sex workers (FSW) exhibit elevated risk of HIV and substance use. However, there is limited study of how distinct substance use typologies influence HIV treatment outcomes among FSW. Setting: A cross-sectional survey with objective viral load assessments of 1,391 FSW enrolled into a treatment optimization-focused trial in Durban, South Africa (2018-2020). Methods: We used latent class analysis to uncover discrete patterns in past-month self-reported use of the following substances: heavy alcohol use, cannabis, cocaine, crack, ecstasy, methamphetamine, heroin, and whoonga. We used Wald tests to identify multilevel predictors of latent class membership and multivariable mixture modeling to quantify associations of substance use classes with HIV viremia (>50 RNA copies/mL). Results: Substance use (87%) and HIV viremia (62%) were highly prevalent. LCA uncovered three polysubstance use profiles: Heavy Alcohol Use Only (∼54%); Cannabis, Heavy Alcohol, & Crack Use (∼28%); and Whoonga & Crack Use (∼18%). Whoonga & Crack Use was associated with social and structural adversities, including homelessness, outdoor/public sex work, HIV stigma, and violence. Relative to Heavy Alcohol Use Only, HIV viremia was significantly higher in the Whoonga & Crack Use class (adjusted odds ratio [adjOR] 1.97, 95% confidence interval [95%CI] 1.13-3.43) but not in the Cannabis, Heavy Alcohol, & Crack Use class (adjOR 1.17, 95%CI 0.74-1.86). Conclusion: HIV viremia differed significantly across identified polysubstance use profiles among South African FSW. Integrating drug treatment and harm reduction services into HIV treatment programs is key to improving virologic outcomes in marginalized communities.