'Prevention packages' could curb HIV transmission in MSM.
Combining available preventive interventions could avert at least one-quarter of new HIV infections among men who have sex with men, according to a statistical model based on transmission data from the United States, Peru, India, and Kenya.
Men who have sex with men (MSM) continue to be at substantial risk for HIV infection worldwide. In many high-income countries, they are the only demographic group that continues to have a rising risk for acquiring HIV. In the United States, their risk for acquiring HIV infections is estimated to be increasing at approximately 8% per year for each year since 2001, according to Dr. Chris Beyrer of Johns Hopkins University; Baltimore, and his associates (Lancet 2012 July 20 [doi:10.1016/S0140-6736(12)60821-6]).
The disproportionate HIV disease burden in MSM is explained largely by the high per-act probability of HIV transmission in unprotected receptive anal sex, a rate estimated at 1.4% and about 18 times greater than the rate estimated for penile-vaginal intercourse, Dr. Beyrer and associates reported.
In a separate paper published in the Lancet issue, Patrick S. Sullivan of Emory University, Atlanta, and his associates reviewed data from 60 articles that tested putative HIV prevention interventions in MSM.
Overall, the data suggest that combinations of prevention approaches, or so-called "prevention packages," are far more likely to succeed than are individual interventions. And, such prevention packages are more likely to succeed "if they target several points in the pathway to HIV infection."
The researcher modeled three prevention packages based on use of condoms, oral pre-exposure prophylaxis--the use of antiretroviral medication in uninfected partners of HIV-discordant couples--and increased/earlier antiretroviral initiation. Between 11% and 29% of incident HIV infections would be averted over 10 years if oral pre-exposure prophylaxis and antiretroviral treatment coverage were assumed to be 40% and if 20% of unprotected anal intercourse encounters were replaced with condom-protected intercourse.
Increasing pre-exposure prophylaxis coverage from 20% to 80% increased the estimated cumulative proportions of infections averted. Increasing the frequency of pre-exposure prophylaxis adherence in men from 50% to 75% resulted in higher estimates of averted HIV incidence in all countries compared with baseline. However, the number of infections averted did not rise when the proportion of men with sufficient adherence was increased from 75% to 90%.
Dr. Sullivan and his associates noted that condoms were a primary focus of prevention efforts at the beginning of the AIDS epidemic, and remain one of the most effective methods for prevention of HIV transmission in HIV-discordant couples. However, condom use in MSM is problematic. Issues include difficulty in negotiating condom use with sexual partners, condom slippage or breakage, and condom availability in developing countries, the authors noted.
Now, there is increasing focus on pre-exposure prophylaxis. On July 16, the Food and Drug Administration approved daily tenofovir and emtricitabine (Truvada) for pre-exposure prophylaxis among HIV-negative high-risk individuals, including MSM.
Data supporting the FDA licensure included those from a trial of 2,499 MSM and transgender women. Use of Truvada was associated with a 44% reduction in the frequency of HIV infections at a median follow-up of 1.2 years compared with placebo. Truvada was fairly well tolerated, but was associated with a transient but significant increase in nausea and unintentional weight loss in the tenofovir and emtricitabine group. Self-reported compliance was 89% or greater at week 4, but participants' drug concentrations suggested that actual adherence was probably lower (N. Engl. J. Med. 2010;363:2587-99).
All authors reported having no conflicts.
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|Title Annotation:||INFECTIOUS DISEASES|
|Author:||Tucker, Miriam E.|
|Publication:||Internal Medicine News|
|Date:||Aug 1, 2012|
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