Gladstone Institute of Virology and Immunology, San Francisco, California, United States of America ; University of California, Berkeley, California, United States of America.
University of California San Francisco, San Francisco, California, United States of America.
PLoS One. 2013 Dec 18;8(12):e81997. doi: 10.1371/journal.pone.0081997. eCollection 2013.
Preexposure prophylaxis (PrEP) with emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) reduced HIV acquisition in the iPrEx trial among men who have sex with men and transgender women. Self-reported sexual risk behavior decreased overall, but may be affected by reporting bias. We evaluated potential risk compensation using biomarkers of sexual risk behavior.
Sexual practices were assessed at baseline and quarterly thereafter; perceived treatment assignment and PrEP efficacy beliefs were assessed at 12 weeks. Among participants with ≥1 follow-up behavioral assessment, sexual behavior, syphilis, and HIV infection were compared by perceived treatment assignment, actual treatment assignment, and perceived PrEP efficacy.
Overall, acute HIV infection and syphilis decreased during follow-up. Compared with participants believing they were receiving placebo, participants believing they were receiving FTC/TDF reported more receptive anal intercourse partners prior to initiating drug (12.8 vs. 7.7, P = 0.04). Belief in receiving FTC/TDF was not associated with an increase in receptive anal intercourse with no condom (ncRAI) from baseline through follow-up (risk ratio [RR] 0.9, 95% confidence interval [CI]: 0.6-1.4; P = 0.75), nor with a decrease after stopping study drug (RR 0.8, 95% CI: 0.5-1.3; P = 0.46). In the placebo arm, there were trends toward lower HIV incidence among participants believing they were receiving FTC/TDF (incidence rate ratio [IRR] 0.8, 95% CI: 0.4-1.8; P = 0.26) and also believing it was highly effective (IRR 0.5, 95% CI: 0.1-1.7; P = 0.12).
There was no evidence of sexual risk compensation in iPrEx. Participants believing they were receiving FTC/TDF had more partners prior to initiating drug, suggesting that risk behavior was not a consequence of PrEP use.
在 iPrEx 试验中，恩曲他滨/替诺福韦二吡呋酯（FTC/TDF）的暴露前预防（PrEP）降低了男男性行为者和跨性别女性的 HIV 感染率。总的来说，自我报告的性风险行为有所减少，但可能受到报告偏倚的影响。我们使用性行为生物标志物评估了潜在的风险补偿。
在基线和此后每季度评估性行为；在 12 周时评估感知治疗分配和 PrEP 疗效信念。在至少有 1 次随访行为评估的参与者中，根据感知治疗分配、实际治疗分配和感知 PrEP 疗效比较性行为、梅毒和 HIV 感染。
总的来说，在随访期间，急性 HIV 感染和梅毒感染有所减少。与认为自己接受安慰剂的参与者相比，认为自己接受 FTC/TDF 的参与者在开始用药前报告了更多的接受肛交的性伴侣（12.8 对 7.7，P=0.04）。相信接受 FTC/TDF 治疗与基线至随访期间无保护肛交（ncRAI）的增加无关（风险比 [RR]0.9，95%置信区间 [CI]：0.6-1.4；P=0.75），也与停药后减少无关（RR 0.8，95%CI：0.5-1.3；P=0.46）。在安慰剂组中，认为自己接受 FTC/TDF 治疗的参与者的 HIV 发病率有下降趋势（发病率比 [IRR]0.8，95%CI：0.4-1.8；P=0.26），也认为其非常有效（IRR 0.5，95%CI：0.1-1.7；P=0.12）。
iPrEx 中没有性行为风险补偿的证据。认为自己接受 FTC/TDF 治疗的参与者在开始用药前有更多的性伴侣，这表明风险行为不是 PrEP 使用的结果。
