September 6, 2013
PrEP Did Not Increase Sexual Risks in Study of Gay Men
Pre-exposure prophylaxis (PrEP) did not cause men who have sex with men (MSM) to have riskier sex in a recent trial. However, the study has various important limitations and does not necessarily reflect a real-world setting. Publishing their findings in the Journal of Acquired Immune Deficiency Syndromes, researchers conducted a randomized, double-blind, placebo-controlled trial of Viread (tenofovir) as PrEP with 400 HIV-negative MSM in San Francisco, Atlanta and Boston who had reported anal sex with another man during the past year.
PrEP, in which an HIV antiretroviral or combination ARV pill is taken daily by HIV-negative people at high risk for infection, has been shown in recent research with MSM to significantly lower the risk of transmission. A major concern among researchers, however, is that PrEP will lead to a phenomenon known as risk compensation: If people taking the therapy consider themselves more invincible to infection, they might take more sexual risks.
The study participants were randomly and evenly divided into four groups, receiving either Viread or a placebo, and starting therapy either upon entering the study, or after a delay of nine months, and then continuing for 24 months. The researchers assessed the participants’ sexual risk factors at the beginning of the study, and then the participants returned every three months to give follow-up interviews.
During the follow-up period, the men’s risk factors either dropped or stayed level, with the average number of sexual partners and the percentage reporting unprotected anal intercourse (UAI) falling and the average number of instances of UAI not changing significantly. During the beginning nine-month period when one half of the group was delayed in taking either Viread or the placebo, changes in risk practices were similar between the two groups. These figures did not change significantly once both groups were taking the therapy or placebo.
The study has some very important limitations: The participants were told that PrEP had no known efficacy, so their willingness to take risks might not translate to real-world scenarios in which men know the therapy could protect them against HIV. The participants’ knowledge that they may have been taking a placebo may also have made them more cautious. Furthermore, self-reports of sexual risk taking may be unreliable, and the men may have been inclined to give more favorable replies, depicting their behavior as less risky than it actually was.
To read the study abstract, click here.
Search: PrEP, pre-exposure prophylaxis, HIV, gay men, men who have sex with men, MSM, Journal of Acquired Immune Deficiency Syndromes, Viread, tenofovir, risk compensation.
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