New Study on PrEP and Sexual Risk Behavior
Do people start having “riskier sex” when they begin taking PrEP to avoid HIV infection? Apparently not, according to a report in the December 18 edition of PLoS ONE.
Although daily Truvada PrEP has been shown to significantly reduce HIV acquisition risk in clinical trials, concern has remained that people who already use condoms for HIV prevention will stop using this effective tool when they start using PrEP; should they then use PrEP inconsistently, they could be at higher risk for HIV. The large iPrEx trial of daily PrEP found no such “risk compensation” reported by study volunteers, but a recent follow-up study looked beyond these self-reported data.
“After the initial iPrEx study, there was concern that self-reported behavior may not tell the whole story,” said iPrEx principal investigator Robert Grant in a press release from the University of California at San Francisco. In follow-up research, Grant and colleagues assessed PrEP users’ sexual behavior with unique approach: “Here, we not only gathered behavioral data, but we also tested each participant for both HIV and syphilis—allowing us to map over time how reported changes in overall behavior correlated with actual changes in infection rates.”
The result? “If risk compensation were occurring, those who believed they were receiving Truvada and that it was effective would be more likely to increase their sexual risk behavior,” explained Julia Marcus, first author of the PLoS ONE article, in the same press release. “However, our results revealed the opposite: rates of both HIV and syphilis infections went down, and there was no increase in sexual risk behavior.”
To learn more about the study, and what it means for real-world use of PrEP, see Liz Highleyman’s summary of the article, excerpted below and available in full at HIVandHepatitis.com. And for answers to your questions about PrEP and where it fits in the HIV prevention toolkit, visit PrEPfacts.org.
By Liz Highleyman
December 23, 2013
Using Truvada (tenofovir/emtricitabine) for pre-exposure prophylaxis (PrEP) to prevent HIV infection was not associated with an increase in sex without condoms and it appears to promote active engagement in risk reduction, according to a report in the December 18, 2013, edition of PLoS ONE.
…Julia Marcus and Robert Grant from the Gladstone Institute of Virology and Immunology and colleagues aimed to determine whether people who used PrEP in the study appeared to be having more risky sex. Self-reported sexual risk behavior decreased overall in iPrEx, but this may be affected by reporting bias, they noted as background. This analysis, therefore, looked at biomarkers of sexual risk behavior.
Sexual practices were assessed at study entry and then quarterly thereafter. At 12 weeks, participants were asked whether they thought they had been randomly assigned to Truvada or placebo and how effective they thought PrEP would be. Among participants with at least 1 follow-up assessment, sexual behavior, prevalence of syphilis, and HIV infection were compared according to perceived treatment assignment, actual treatment assignment, and perceived PrEP efficacy.
- Overall, both acute HIV infection and syphilis incidence decreased during follow-up.
- Participants who thought they were receiving Truvada reported receptive anal intercourse with more partners prior to starting PrEP compared with those who thought they were receiving placebo (12.8 vs 7.7, respectively).
- Believing one had been assigned to take Truvada was not associated with an increase in receptive anal intercourse without a condom.
- People who thought they were assigned to Truvada also did not report a decrease in sex without condoms after stopping their study drug.
- In the placebo arm, there were trends toward lower HIV incidence among participants who believed they were receiving Truvada (incidence rate ratio [IRR] 0.8; p=0.26) and who thought Truvada was highly effective (IRR 0.5; p=0.12).
- Younger men, transgender women, and participants who reported depression were more likely to have anal sex without condoms.
“There was no evidence of sexual risk compensation in iPrEx,” the study authors concluded….