April 29, 2013
Truvada (tenofovir) is used for pre-exposure prophylaxis (PrEP) to reduce risk of HIV infection among risk-taking HIV-negative gay men. Researchers investigated whether use of Truvada as PrEP encouraged risk-taking among men who have sex with men (MSM). The researchers studied 400 gay men for 24 months between 2005 and 2007 in a randomized double-blind placebo study. One group of participants began taking Truvada at the outset of the study and the other began nine months later. Researchers interviewed the men at entry into the study and every three months concerning sexual risk-taking and use of recreational drugs and erectile dysfunction medications.
Participants had an average of 7.25 partners in the three months prior to the study. This number decreased to 6 partners between months 3 and 9 and to 5.71 in the second year. Before baseline, 57 percent of participants reported unprotected anal sex. The number dropped to 48 percent between months 3 and 9, and rose to 52 percent in the second year. Also, at baseline, 29 percent of participants reported unprotected intercourse with a man they knew to be HIV-positive. This number dropped to 21 percent between months 3 and 9 and increased slightly to 22 percent in the second year. Unprotected sex with partners they knew to be HIV-positive decreased from 2 at the beginning of the study to 1.37 during the second year, and unprotected anal intercourse with partners believed to be HIV-negative increased from 2.75 at baseline to 4 during year two.
Findings indicate that the use of Truvada as PrEP did not increase sexual risk-taking among HIV-negative MSM. However, findings are tempered by the fact that the study provided the participants with risk-reduction counseling, condoms and lubricant, routine HIV tests, STD testing, and links to prevention services. The researchers acknowledge that these measures may have affected the observed risk reduction and risk declines.
The full report, "Sexual Risk Behavior Among HIV-Uninfected Men Who Have Sex with Men (MSM) Participating in a Tenofovir Pre-Exposure Prophylaxis (PrEP) Randomized Trial in the United States," is published online in the Journal of Acquired Immune Deficiency Syndromes (2013; doi: 10.1097/QAI.0b013e31828f097a).