Using Drugs to Prevent HIV Infection: Who, What, and When?
Using Drugs to Prevent HIV Infection: Who, What, and When?
Editor's Note: In 2012, the combination of tenofovir (TDF) and emtricitabine (FTC) was approved by the US Food and Drug Administration for preexposure prophylaxis (PrEP) to reduce the risk for sexually acquired HIV infection in adults at high risk. Interim guidance documents released by the US Centers for Disease Control and Prevention (CDC) focused on the use of TDF/FTC as HIV PrEP in men who have sex with men (MSM), high-risk heterosexually active adults, and intravenous-drug users. In May 2014, CDC released a comprehensive clinical practice guideline for the use of PrEP in the prevention of HIV infection in the United States.
In an interview with Medscape, Myron S. Cohen, MD, Chief of the Division of Infectious Diseases at the University of North Carolina in Chapel Hill, considered some of the key clinical issues facing practitioners as they try to understand how best to use HIV PrEP in real-life settings.
Medscape: In looking at the target groups for potential PrEP, one group that the new guideline highlights is serodiscordant couples. Given what we know about the value of "treatment as prevention" strategies in lowering the risk for HIV transmission, where might a PrEP regimen fit?
Dr. Cohen: When two people are in a stable relationship and one person is HIV-positive and the other is HIV-negative, unequivocally the best strategy is to treat the infected person with antiretroviral therapy (ART).
In the United States, guidelines call for immediate treatment of HIV in all persons who are acutely and clinically infected so as to achieve virologic suppression. The literature strongly supports the idea that transmission events are drastically reduced when the person who is infected is virologically suppressed.
So in the situation of a serologically discordant couple, I would find it difficult to say that the HIV-positive partner is going to be treated to virologic suppression and that in addition to that, the HIV-negative partner will take TDF/FTC or some other prophylactic regimen for the rest of the relationship of 10, 20, or 30 years. It is not really a credible scenario.
A more likely use is when you have a sexually active couple in which one partner is newly diagnosed and is just starting ART. In such a case, it would make sense to provide PrEP to the uninfected partner during the window of time until the infected partner achieves virologic suppression. Also, because HIV-negative women may be more susceptible during pregnancy and conception, PrEP could be used during that window of time. Finally, if the HIV-negative person is distrustful of the adherence of their HIV-infected partner or has other high-risk behaviors himself, PrEP might be considered
But this discussion highlights the fundamental problem with any PrEP strategy: We don't really know at what point to start, and most important, we don't know when to stop. We generally consider prophylactic therapy as a self-limited exposure to a preventive strategy. With HIV PrEP, what's the end goal? We know we can't put an uninfected person on a daily PrEP regimen forever, so we need to do more work to figure out the best use of PrEP.
Editor's Note: In 2012, the combination of tenofovir (TDF) and emtricitabine (FTC) was approved by the US Food and Drug Administration for preexposure prophylaxis (PrEP) to reduce the risk for sexually acquired HIV infection in adults at high risk. Interim guidance documents released by the US Centers for Disease Control and Prevention (CDC) focused on the use of TDF/FTC as HIV PrEP in men who have sex with men (MSM), high-risk heterosexually active adults, and intravenous-drug users. In May 2014, CDC released a comprehensive clinical practice guideline for the use of PrEP in the prevention of HIV infection in the United States.
In an interview with Medscape, Myron S. Cohen, MD, Chief of the Division of Infectious Diseases at the University of North Carolina in Chapel Hill, considered some of the key clinical issues facing practitioners as they try to understand how best to use HIV PrEP in real-life settings.
Should We Treat the Uninfected Partner of a Serodiscordant Couple?
Medscape: In looking at the target groups for potential PrEP, one group that the new guideline highlights is serodiscordant couples. Given what we know about the value of "treatment as prevention" strategies in lowering the risk for HIV transmission, where might a PrEP regimen fit?
Dr. Cohen: When two people are in a stable relationship and one person is HIV-positive and the other is HIV-negative, unequivocally the best strategy is to treat the infected person with antiretroviral therapy (ART).
In the United States, guidelines call for immediate treatment of HIV in all persons who are acutely and clinically infected so as to achieve virologic suppression. The literature strongly supports the idea that transmission events are drastically reduced when the person who is infected is virologically suppressed.
So in the situation of a serologically discordant couple, I would find it difficult to say that the HIV-positive partner is going to be treated to virologic suppression and that in addition to that, the HIV-negative partner will take TDF/FTC or some other prophylactic regimen for the rest of the relationship of 10, 20, or 30 years. It is not really a credible scenario.
A more likely use is when you have a sexually active couple in which one partner is newly diagnosed and is just starting ART. In such a case, it would make sense to provide PrEP to the uninfected partner during the window of time until the infected partner achieves virologic suppression. Also, because HIV-negative women may be more susceptible during pregnancy and conception, PrEP could be used during that window of time. Finally, if the HIV-negative person is distrustful of the adherence of their HIV-infected partner or has other high-risk behaviors himself, PrEP might be considered
But this discussion highlights the fundamental problem with any PrEP strategy: We don't really know at what point to start, and most important, we don't know when to stop. We generally consider prophylactic therapy as a self-limited exposure to a preventive strategy. With HIV PrEP, what's the end goal? We know we can't put an uninfected person on a daily PrEP regimen forever, so we need to do more work to figure out the best use of PrEP.
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