IPrEX Study Methodology and Results

Men who have sex with men remain the largest segment of the US population at risk for HIV infection. Despite expanded HIV testing, community-based behavioral interventions to reduce risk behaviors, promotion of condom use, increased detection and treatment of other sexually transmitted diseases such as syphilis, gonorrhea and chlamydia, and mental health counseling to address substance abuse, new HIV infections among MSM have continued to increase since the mid-1990s. Pre-exposure prophylaxis (PrEP) is a unique approach to HIV prevention in which antiretroviral drugs are used by HIV-uninfected individuals prior to a potential HIV exposure. PrEP is distinct from post-exposure prophylaxis (PEP), where an individual takes ARV medication promptly after a possible HIV exposure to avoid infection. The Pre-Exposure Prophylaxis Initiative (iPrEX), an international, randomized, double-blind, placebo-controlled phase III clinical trial was conducted to evaluate the efficacy of daily oral use of TDF (tenofovir disoproxil fumarate) and FTC (emtricitabine) among 2,499 HIV-uninfected men and 29 transgendered men who reported engaging in high-risk sexual behaviors with other men within the preceding 6 months. Results of this trial were published in the New England Journal of Medicine in November 2010.