TRENDS IN REPORTED SEXUAL BEHAVIOR AND Y-CHROMOSOMAL DNA DETECTION AMONG FEMALE SEX WORKERS IN THE SENEGAL PrEP DEMONSTRATION PROJECT.

Background Preexposure prophylaxis (PrEP) can reduce HIV acquisition among female sex workers (FSWs). However, changes in condomless sex frequency after PrEP initiation could reduce PrEP effectiveness when PrEP adherence is suboptimal as well as increase the risk of acquiring other sexually transmitted infections. Objective measures of condomless sex may be more accurate for determining changes in sexual behavior than self-reported measures. Methods We longitudinally measured self-reported condom use, number of clients, and presence of Y-chromosomal DNA (Yc-DNA) in vaginal swabs among 267 FSWs accessing PrEP at 4 clinics in Senegal between 2015 and 2016. We assessed trends in sexual behavior over time since PrEP initiation using generalized estimating equations and evaluated predictors of Yc-DNA detection. Results We found no increase in self-reported condomless sex with clients (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.89-1.00), main partners (OR, 0.99; 95% CI, 0.96-1.02), or Yc-DNA detection (OR, 0.99; 95% CI, 0.90-1.08) over time since initiation. Y-chromosomal DNA was detected in 34 (22%) of 154 swabs tested and in 15 (26%) of 58 swabs from FSW reporting consistent condom use among both clients and main partners. Self-reported condom use with clients or main partners did not predict Yc-DNA detection. Conclusions In a FSW PrEP demonstration project in Senegal, we found no evidence of risk compensation among FSWs on PrEP as measured by self-reported behavior or through Yc-DNA detection. Y-chromosomal DNA detection was frequently detected among FSWs reporting consistent condom use, highlighting limitations of self-reported sexual behavioral measures.