HIV Prevention: Identifying the Barriers to PrEP Usage

Costs, Adherence Present Formidable Obstacles to PrEP Enrollment

Image courtesy Gilead Sciences

It has been shown that the daily use of the antiretroviral drug, Truvada, can significantly reduce the risk of infection in HIV-negative individuals in a serodiscordant relationship (i.e., where one partner is HIV-positive and the other is HIV-negative). The strategy, known as pre-exposure prophylaxis (or PrEP), has been shown to reduce transmission risk by anywhere from 62% to 75% if taken with consistent, uninterrupted adherence.

From a statistical viewpoint, the figures strongly support the use of PrEP as part of an overall HIV prevention strategy. However, from a real-life perspective, the numbers may not be all that convincing, with the words "consistent" and "uninterrupted" presenting potential barriers to those who might otherwise enlist.

In fact, according to industry research, only 1,774 people in the U.S. had filled prescriptions for Truvada for PrEP between January 2011 and March 2013. That's a startlingly low number, given that 50,000 new HIV infections are estimated to occur in the U.S. every year.

The figures bring into the spotlight many of the issues that make PrEP ideal in a research setting, but less so when placed in the context of the real world. And it's not simply an issue of education or awareness (although these are key factors). Clearly there's something else going on.

A 2012 survey conducted by the U.S.

Centers for Disease Control and Prevention (CDC) concluded that more than a third of the HIV-positive Americans on antiretroviral therapy (ART) are unable to maintain daily drug adherence—and this for a HIV population where adherence relates to directly to duration and quality of life.

Can we expect the barriers to be any less for people who take ART not for "survival" per se, but for HIV prevention?

After all, while condoms are known to provide far greater protection, statistics show that they are used in only two out of three sexual acts at best.

So while some might ask, "How difficult can it be to take one little pill a day?", most research shows that daily adherence may be a too formidable hurdle to overcome. Consider that chronic medication for diabetes or heart disease require as little as 70% adherence (or the equivalent of nine missed doses per month). By contrast, PrEP demands near perfect adherence in order to achieve the protective goals.

Several recent studies confirm the challenges. In 2013, the VOICE Study—which looked at the use of PrEP among 5,029, at-risk African women—was declared futile when it was shown that only 30% were able to maintain daily adherence to therapy. Similar results were seen in the FEM-PrEP Study, which was also discontinued due to low adherence rates among those taking daily Truvada.

In light of these studies and the lower-than-expected numbers of PrEP registrants, greater emphasis may need to be placed on targeted education, whereby people in serodiscordant relationships (including those wanting to conceive) are advised about PrEP as a course of general family practice, rather than just in a specialized HIV setting.

Policy makers may also need to assess whether the cost of PrEP, estimated to be around $12,000 per year, may be a limiting factor for those with insurance plans that do not fully cover its use.

In a 2013 survey of U.S. and Canadian infectious disease specialists, 74% supported the use of PrEP on a population-wide basis. However, of this group, only 9% actually prescribed it to patients.

It is hoped that recommendations made by the CDC in May 2014, calling for the use of PrEP in populations considered at high risk of infection, will increase lagging enrollments in the U.S. Groups targeted by the CDC include:


Rawlings K, Mera R, Pechonkina A, et al. "Status of Truvada for HIV pre-exposure prophylaxis (PrEP) in the United States: an early drug utilization analysis." 53rd ICAAC Interscience Conference on Antimicrobial Agents and Chemotherapy; Denver, Colorado; September 10-13, 2013; abstract H-663a.

U.S. Centers for Disease Control and Prevention (CDC). "CDC Fact Sheet | HIV in the United States: The Stages of Care." Atlanta, Georgia; published July 2012.

Anderson, J. "Condom Use and HIV Risk Among US Adults." American Journal of Public Health. June 2003; 93(6):912-914.

Microbicides Trial Network (MTN). "MTN Statement on Decision to Discontinue Use of Oral Tenofovir Tablets in VOICE, a Major HIV Prevention Study in Women." Press release issued September 28, 2011.

National Institute of Allergies and Infectious Diseases (NIAID). "The FEM-PrEP HIV Prevention Study and Its Implications for NIAID Research." Bethesda, Maryland; press release issued April 18, 2011.

MacNeil, D. "Advocating PIll, U.S. Signals Shift to Prevent HIV." New York Times. Published May 14, 2014.

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