The addition of daily oral pre-exposure prophylaxis (PrEP) for prevention of HIV infection for men who have sex with men at risk of HIV infection was strongly supported as the result of an open-label randomized trial of 544 HIV-negative participants. Enrollees were men who have sex with men who were HIV-negative who had had anal intercourse without condom use in the previous 90 days and were randomly assigned to receive daily combined tenofovir disoproxil fumarate (245 mg) and emtricitabine (200 mg) either immediately or after a deferral period of 1 year. Researchers found:

• 3 HIV infections occurred in the immediate group vs 20 in the deferred group.

• There was no evidence of an increase in other sexually transmitted diseases.

Citation: McCormack S, Dunn DT, Desai M, et al. Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomized trial. Lancet. [Published online ahead of print September 10, 2015]. doi:10.1016/S0140-6736(15)00056-2.

Commentary: Previous randomized trials have show that daily pre-exposure prophylaxis (PrEP) for high risk HIV-negative individuals is effective at decreasing the rate of acquisition of HIV infection. Efficacy in previous trials at preventing HIV acquisition was approximately 70%^1,2. The question that has been asked since that time in a real-world setting is whether taking PrEP would increase risky behavior in such a manner as to offset the beneficial effects of PrEP. This study confirmed the effectiveness of PrEP and shows that prescription of PrEP does not lead to an increase in risk-taking sexual behavior. PrEP is now being recommended for patients by the CDC. There has been a lot in layman literature about PrEP, so it is useful to know about. For more information on PrEP, see http://www.cdc.gov/hiv/basics/prep.html . —Neil Skolnik, MD

1. Grant RM, Lama JR, Anderson PL, et al. Preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med 2010; 363: 2587–99.

2. Baeten JM, Donnell D, Ndase P, et al. Antiretroviral prophylaxis for HIV prevention in heterosexual men and women. N Engl J Med 2012; 367:399–410.