Published November, 2014

HIV Pre-Exposure Prophylaxis in Men Who Have Sex with Men and Transgender Women: A Secondary Analysis of a Phase 3 Randomised Controlled Efficacy Trial, The Lancet, Susan Buchbinder et al 2014

Men who have sex with men (MSM) and transgender women make up the largest proportion of new HIV infections throughout North and South America, Western Europe, Asia, and Australia. Despite increases in frequency of HIV testing, knowledge of HIV serostatus, and access to antiretroviral therapy, infection rates among MSM and transgender women are stable or rising.

In this study, the goal was to estimate the population attributable fraction (PAF) and the number needed to treat (NNT) of participants in an iPrEx (Pre-Exposure Prophylaxis Initiative) trial to identify subpopulations of people for whom pre-exposure prophylaxis may have the largest effect.

The report found that pre-exposure prophylaxis may be most effective at a population level if targeted toward MSM and transgender women who report receptive anal intercourse without a condom, even if they perceive their partners to be HIV negative. Substance use history and testing for STIs should also inform individual decisions to start pre-exposure prophylaxis. Consideration of the PAF and NNT can aid in discussion of the benefits and risks of pre-exposure prophylaxis with MSM and transgender women.