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U.S. researchers study steps needed to increase PrEP use

2 September 2015

Across all high-income countries, including Canada, HIV continues to spread. One population that is disproportionally hit by HIV is men who have sex with men (MSM).

In the past several years, clinical trials of medicine taken before sexual encounters—this practice is called pre-exposure prophylaxis (PrEP)— have found PrEP effective at reducing the risk of acquiring HIV, particularly among MSM. Results from three PrEP clinical trials in sub-Saharan Africa with women did not produce promising results, largely because such trials were plagued by poor adherence.

In theory, widespread use of PrEP by MSM could help to greatly reduce new HIV infections. In the U.S., a fixed-dose combination of two anti-HIV drugs, tenofovir + FTC, is sold in one pill called Truvada and has been widely used in clinical trials of PrEP. Truvada is approved for use as PrEP in the U.S. Truvada is also approved for use as part of combination anti-HIV therapy in many countries. The U.S. Centers for Disease Control and Prevention (CDC) has developed guidelines to help doctors and nurses prescribe PrEP.

However, surveys have found that while there is increasing interest in PrEP by some MSM, widespread use of PrEP has not followed as a result of the approval by the U.S. Food and Drug Administration (FDA) of Truvada for this indication (PrEP).

Researchers in Atlanta have been investigating the different steps involved in the PrEP continuum of care (or PrEP cascade of care). They found extensive barriers to PrEP and suggested that unless such barriers are addressed PrEP will not become a widely used tool to help stop the spread of HIV.

Study details

Researchers in Atlanta have been conducting a study called Involvement. Data from Involvement were used to develop models of the PrEP cascade, so it is important to briefly review this study.

Between 2010 and 2012, researchers used Facebook to recruit men who were either black or white and who were MSM but who were not in a mutually monogamous relationship. About 40% of participants were relatively young—between 18 and 24 years. At the start of the study, all participants tested negative for HIV. During the study, participants were screened for and, when necessary, treated for sexually transmitted infections (STIs). They also completed surveys about their sexual behaviours. Participants visited the study clinics up to five times over a period of two years, or less if they tested positive for HIV. The study ended in 2014.

Overall, researchers recruited 562 MSM—260 of whom were black and 302 who were white. By the end of Involvement, 32 MSM had become HIV positive. This would result in the infections being distributed as follows:

  • 7% per year among black MSM
  • 2% per year among white MSM

The researchers found that the group hardest hit by new cases of HIV was young black men, aged 18 to 24 years.


The researchers projected their findings from the Involvement study onto a potential PrEP care cascade, using a mathematical model. An assumption that underpinned the model was that the use of PrEP would result in about a 51% reduction in new cases of HIV. Data for this assumption were based on a 72-week observational study of 1,603 people in the U.S. who could obtain Truvada at no cost. In the same study, researchers found that participants who took Truvada every day, exactly as prescribed, did not become HIV positive.


Using what the Atlanta researchers called “generous, optimistic estimates,” they predicted that “few Atlanta MSM will achieve protection from HIV with PrEP given significant barriers currently in place.”

After modelling their findings onto a group of 562 MSM, the Atlanta researchers predicted what was likely to happen at each step of the PrEP care cascade, as follows:

  • 100% of MSM were identified as sexually active
  • 80% of these men were aware of and willing to take PrEP
  • 43% had access to healthcare and subsidized medicines (including PrEP)
  • 30% were likely to receive a prescription for PrEP
  • 15% of MSM were expected to achieve protection from HIV

In assessing the projections by race, the research team expected 18% of white MSM and 12% of black MSM to be protected from HIV.

Based on the Atlanta projections, much work needs to be done to strengthen the PrEP continuum of care at every stage. Furthermore, the researchers added that “…large, sustained changes [that facilitate access to PrEP] are needed to achieve levels of HIV protection that might alter the course of the epidemic.”

What are the changes needed?

Given the background of increasing numbers of newly infected people, the researchers stated: “Each step of [the PrEP] continuum represents a critical intervention point that demands immediate attention.” The researchers proposed several steps that could help to reduce barriers to PrEP, as follows:

  • Launching “mass national awareness campaigns” about PrEP could increase interest in using PrEP.
  • Access to PrEP could be increased by policy changes that significantly subsidize the cost.
  • The likelihood of doctors prescribing PrEP could increase “based on concerted provider training efforts and development of custom algorithms tailored to local epidemics.”

Intervening in an epidemic

As HIV rates are increasing at a relatively quick pace among MSM in Atlanta, the researchers stated: “…novel strategies for PrEP delivery that circumvent the barriers presented in the PrEP care continuum are needed for MSM most at risk for HIV.”

Furthermore, they noted: “In our opinion, this should include free or low-cost PrEP programs targeted at those at highest risk [for HIV]. An important first step would be ensuring that PrEP is freely available where at-risk MSM are currently accessing services, including centres that provide [screening and treatment for sexually transmitted infections], HIV testing services, and/or other HIV prevention services.”

Comments on the study

In reviewing the findings from Atlanta, HIV prevention expert professor Ken Mayer, MD, of Harvard University, agreed that there are issues impeding the use of PrEP, such as the following:

  • Although awareness of PrEP is increasing, “MSM who are poorer or less educated appear to be less informed about PrEP.”
  • Some people may mistrust the medical-healthcare system because of previous unethical experiments. As a result, some people may “tune out new information.”
  • Media campaigns by some “‘PrEP denialists may have created confusion.”

Professor Mayer noted that “since PrEP is a biomedical intervention, accessing it requires either [informed citizens] or a busy clinician taking the time to determine whether a patient might benefit from PrEP. Primary care providers do not routinely ask about sexual orientation or behaviour, so many opportunities to initiate PrEP may be missed. Moreover, patients may be uncomfortable to request PrEP, since they may anticipate moralistic conversations if they disclose their sexual orientation and preference for condomless sex.”

Professor Mayer also points out another issue: “There is no consensus among clinicians about who should [prescribe] PrEP.” By this he means that while some people think that primary care doctors and nurses should prescribe it, these care providers may feel that “they are not equipped to discuss the nuances of sexual behaviour and are not familiar with prescribing [anti-HIV medicines].” A related issue, he says, is that “infectious disease specialists who might only provide primary care for people living with HIV might not be comfortable in managing people who are otherwise healthy who request prophylaxis because of behavioural risk.”

Professor Mayer suggests that “the use of electronic technologies whereby patients can self-report their behavioural risks, either at home or in waiting rooms, could save time for clinicians to routinely determine whether a patient's recent behavioural pattern might merit a PrEP discussion.”

A common theme

Although the Atlanta research clearly identifies barriers to PrEP in that city, not all the news from the U.S. is dismal. Professor Mayer states that researchers in San Francisco estimate that about 10% of MSM at risk for HIV infection have used PrEP. In Boston, one community clinic has had more than 500 people start using PrEP in 2015. What San Francisco and Boston have in common, says Mayer, “is an environment that has supported civil equality for sexual and gender minorities, early implementation of health reform, and access to culturally tailored behavioural health programs.”

Bear in mind

Although the present analysis is based on data from Atlanta, many other cities and regions in the U.S, Canada and around the world are still trying to turn the tide on new HIV infections. Therefore, the overall thrust of this research about barriers to PrEP likely applies elsewhere.

PrEP under review by Health Canada

In Canada, Truvada is approved for use as part of combination therapy for people with HIV. Gilead Sciences, manufacturer of Truvada, is seeking approval from regulatory authorities in Canada for an additional use of Truvada—as PrEP—together with other safer-sex practices (Gilead Sciences Canada, personal communication ). Gilead is also seeking approval for Truvada as PrEP in other countries, including Australia, Brazil and Thailand. Regulatory authorities in France have requested data on Truvada for PrEP and are reviewing it. If PrEP is approved in Canada and other countries for the prevention of HIV infection, work on the PrEP care continuum will need to intensify so that another tool will be available to help stop the spread of HIV.


Pre-exposure prophylaxis (PrEP) – CATIE Fact Sheet

Interim guidance on providing HIV PrEP – Quebec Ministry of Health (French only)

Clinical practice guidelines for providing PrEP – CDC

Clinical providers' supplement for providing PrEP – CDC

—Sean R. Hosein


  1. Kelley CF, Kahle E, Siegler A, et al. Applying a PrEP Continuum of Care for men who have sex with men in Atlanta, GA. Clinical Infectious Diseases . 2015; in press .
  2. Mayer KH, Krakower DS. If PrEP decreases HIV transmission, what is impeding its uptake? Clinical Infectious Diseases . 2015; in press .
  3. Mayer KH, Ramjee G. The current status of the use of oral medication to prevent HIV transmission. Current Opinion in HIV/AIDS . 2015 Jul;10(4):226-32.

—Sean R. Hosein


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From Canadian AIDS Treatment Information Exchange (CATIE). For more information visit CATIE's Information Network at


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