- Category: Pre-exposure Prophylaxis (PrEP)
- Published on Tuesday, 01 February 2011 00:00
- Written by Liz Highleyman
The U.S. Centers for Disease Control and Prevention (CDC) this week issued interim guidance regarding the use of tenofovir/emtricitabine (Truvada) for pre-exposure prophylaxis (PrEP) against HIV infection. The guidelines, published in the January 28, 2011, Morbidity and Mortality Weekly Report, note the limitations of the recent iPrEx trial and recommend PrEP only for gay/bisexual men with "substantial, ongoing, high risk" for acquiring HIV.
As reported this past fall, the iPrEX trial, described in the November 23, 2010, advance online edition of the New England Journal of Medicine (December 30, 2010 print edition), was the first to show that daily oral tenofovir/emtricitabine PrEP could reduce the risk of HIV infection in humans.
This study -- which included more than 2000 men who have sex with men (MSM) in South America, South Africa, Thailand, and the U.S. (Boston and San Francisco) -- found that those who used PrEP daily were 44% less likely to acquire HIV, while the subset of men who achieved good adherence lowered their risk by 73%.
The trial results were greeted with enthusiasm -- especially in the wake of disappointing results from several previous biomedical prevention trials -- but also numerous questions about who could potentially benefit, the long-term risks of tenofovir/emtricitabine, and cost and access issues.
While Truvada is not approved by the U.S. Food and Drug Administration (FDA) for HIV prevention, doctors may prescribe drugs for off-label use, and some gay men are eager to start using PrEP right away. The new guidance is intended to offer instructions and cautions for people interested in using PrEP now, while awaiting more extensive clinical trial data regarding longer-term use and other at-risk populations. The CDC and Public Health Service are currently working on more definitive guidelines.
The CDC has provided a chart summarizing the guidance, included below and available online at www.cdc.gov/nchhstp/newsroom/PrEPMSMGuidanceGraphic.html.
Key points include:
- Confirm that the person seeking PrEP is at substantial, ongoing, high risk for acquiring HIV infection.
- Test for HIV -- including, if symptomatic, acute HIV infection that may not be detectable with a standard antibody test -- since using just 2 antiretroviral drugs could lead to resistance if HIV is present; repeat HIV testing every 2-3 months while on PrEP.
- Screen for and treat other sexually transmitted diseases; repeat STD testing every 6 months while on PrEP.
- Test for kidney function (creatinine clearance), because tenofovir has been associated with kidney problems in susceptible individuals; monitor kidney function after 3 months and then annually while on PrEP.
- Screen for, and if uninfected vaccinate against, hepatitis B; if infected, consider the dual use of Truvada for treatment, since tenofovir and emtricitabine are active against hepatitis B virus (HBV) as well as HIV.
- Provide PrEP as part of a comprehensive prevention approach along with risk-reduction counseling and condoms; assess risk behavior every 2-3 months while on PrEP.
- Stress the importance of and offer support for adherence; iPrEX did not provide evidence that using Truvada only before or after sex is effective (this is currently under study).
In an editorial note accompanying the MMWR report of the iPrEx data, the authors elaborated, "When evaluating MSM for the prescription of PrEP medications, it is important to establish whether other effective risk-reduction measures (e.g., condom use) are not being used consistently and to ascertain that the risk for HIV acquisition is high (e.g., frequent partner change or concurrent partners in a geographic setting with high HIV prevalence) because these patients might benefit most from the addition of PrEP to their HIV prevention regimen."
"PrEP has the potential to contribute to effective and safe HIV prevention for MSM," they continued, "if 1) it is targeted to MSM at high risk for HIV acquisition; 2) it is delivered as part of a comprehensive set of prevention services, including risk-reduction and PrEP medication adherence counseling, ready access to condoms, and diagnosis and treatment of sexually transmitted infections; and 3) it is accompanied by monitoring of HIV status, side effects, adherence, and risk behaviors at regular intervals."
Investigator affiliation: National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC.
DK Smith, RM Grant, PJ Weidle, and others (CDC). Interim Guidance: Preexposure Prophylaxis for the Prevention of HIV Infection in Men Who Have Sex with Men. Morbidity and Mortality Weekly Report 60(03): 65-68 (abstract). January 28, 2011.
CDC NCHHSTP Media Team. CDC Issues Interim Physician Guidance on PrEP for MSM. Media advisory. January 27, 2011.