Taking Truvada (emtricitabine/tenofovir) as pre-exposure prophylaxis (PrEP) did not lead HIV-negative people in a large study to take increased sexual risks, although there are caveats to these findings, Reuters reports. Approved in 2012 as an HIV prevention tool that can reduce the risk of transmission by more than 90 percent if used correctly, the antiretroviral has remained controversial, and sparsely used, in no small part because of concerns that it will lead to what is known as risk compensation. This phenomenon takes place when an individual responds to an intervention that lowers the risk of a harm by in turn exposing him or herself to greater risk of that harm—in this case, by having more unprotected sex or having sex with greater numbers of partners, for example. Such increased risk-taking could in theory negate the benefit of PrEP and also lead to the spread of other sexually transmitted infections (STIs).

Researchers at the Gladstone Institutes, an affiliate of the University of California, San Francisco, built upon their three-year 2010 Global iPrEx clinical study of Truvada as PrEP. Publishing their findings in PLOS ONE, they re-examined data of the nearly 2,500 HIV-negative gay men and male-to-female transgender women in six countries who participated, looking specifically at those who reported believing that they were not in the half of the study taking the placebo and also that the drug was working.

Theoretically, those who believed to be on an effective HIV prophylaxis therapy would be more inclined toward risk compensation, but the investigators did not find this to be the case. In fact, the group’s behavior trended toward safer-sex practices. The rate of new HIV infections dropped four-fold. The syphilis rate fell as well.

“Our results suggest that HIV prevention strategies such as Truvada don’t result in risk compensation because they provide an opportunity for participants to actively engage in and reduce their risk of HIV infection,” Gladstone Institutes’ Robert Grant, MD, MPH, who led the research team, said in a release. “Engagement, which also includes counseling, provision of condoms and management of other sexually transmitted infections, leads to motivation, which comes at a time when motivation for preventing new HIV infections is vital to curbing the spread of this worldwide epidemic.”
A significant caveat of these findings is that they are not taken from a real-world sample. It remains to be seen how risk compensation may play out in the large-scale use of PrEP among populations not under the close watch of a clinical trial.

To read the Reuters story, click here.

To read a release on the study, click here.