Brief Report: Anal Intercourse, HIV-1 Risk, and Efficacy in a Trial of a Dapivirine Vaginal Ring for HIV-1 Prevention.

OBJECTIVES:To describe receptive anal intercourse (RAI) behaviors and correlates in a cohort of sub-Saharan African women, evaluate the association of RAI with HIV-1 risk, and evaluate whether the HIV-1 prevention efficacy of a dapivirine vaginal ring differs among women who reported RAI. DESIGN:Secondary analysis of the MTN-020/ASPIRE trial, a randomized, double-blind, placebo-controlled trial evaluating a dapivirine vaginal ring for HIV-1 prevention. METHODS:At enrollment and month 3, women reported RAI in the prior 3 months in audio computer-assisted self-interviews. We evaluated associations between RAI and participant characteristics with χ and t-tests adjusted for study site. Cox proportional hazards models stratified by study site tested the association of RAI with HIV-1 acquisition and effect modification by RAI. RESULTS:Eighteen percent of women reported any RAI at enrollment and/or month 3, with a median of 2 (interquartile range: 1-4) RAI acts in the prior 3 months, accounting for 1.5% of total sex acts. RAI prevalence was higher among women with lower educational attainment and those reporting transactional sex. In adjusted models, RAI was not associated with HIV-1 acquisition (aHR: 0.93, 95% CI: 0.57 to 1.54). The ring reduced HIV-1 risk by 27% (95% CI: -5 to 49) among women reporting no RAI and by 18% (95% CI: -57 to 57) among women reporting any RAI (interaction P-value = 0.77). CONCLUSIONS:RAI was modestly infrequent and was not associated with reduced HIV-1 protection from the ring, suggesting that, in populations with rates of RAI similar to this cohort, RAI may not appreciably reduce the population-level impact of the dapivirine vaginal ring.