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.
Sexual Risk Behavior Among HIV-Uninfected Men Who Have Sex With Men Participating in a Tenofovir Preexposure Prophylaxis Randomized Trial in the United States.
Liu AY, Vittinghoff E, Chillag K, Mayer K, Thompson M, Grohskopf L, Colfax G, Pathak S, Gvetadze R, Oʼhara B, Collins B, Ackers M, Paxton L, Buchbinder SP.
*Bridge HIV, San Francisco Department of Public Health, San Francisco, CA; †Department of Medicine, University of California San Francisco, San Francisco, CA; ‡Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA; §Fenway Health, Boston, MA; ‖AIDS Research Consortium of Atlanta, Atlanta, GA; ¶Northrop Grumman Corporation, Falls Church, VA; #Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA; **Beth Israel Deaconess Hospital and Harvard Medical School, Boston, MA; ††HIV Prevention Section, San Francisco Department of Public Health, San Francisco, CA; and ‡‡Quantitative Sciences and Data Management branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA.
To evaluate for changes in sexual behaviors associated with daily pill use among men who have sex with men (MSM) participating in a preexposure prophylaxis trial.
Randomized, double-blind, placebo-controlled trial. Participants were randomized 1:1:1:1 to receive tenofovir disoproxil fumarate or placebo at enrollment or after a 9-month delay and followed for 24 months.
Four hundred HIV-negative MSM reporting anal sex with a man in the past 12 months and meeting other eligibility criteria enrolled in San Francisco, Atlanta, and Boston. Sexual risk was assessed at baseline and quarterly visits using Audio Computer-Assisted Self-Interview. The association of pill taking with sexual behavior was evaluated using logistic and negative-binomial regressions for repeated measures.
Overall indices of behavioral risk declined or remained stable during follow-up. Mean number of partners and proportion reporting unprotected anal sex declined during follow-up (P < 0.05), and mean unprotected anal sex episodes remained stable. During the initial 9 months, changes in risk practices were similar in the group that began pills immediately vs. those in the delayed arm. These indices of risk did not differ significantly after initiation of pill use in the delayed arm or continuation of study medication in the immediate arm. Use of poppers, amphetamines, and sexual performance-enhancing drugs were independently associated with one or more indices of sexual risk.
There was no evidence of risk compensation among HIV-uninfected MSM in this clinical trial. Monitoring for risk compensation should continue now that preexposure prophylaxis has been shown to be efficacious in MSM and other populations and will be provided in open-label trials and other contexts.