PROUD Study Dispels Common Concerns About PrEP

Dr. Sheena McCormack

The third in a series of articles about the PrEP findings presented at the 2015 Conference on Retroviruses and Opportunistic Infections. Read part 1 and part 2.

If anyone is questioning whether pre-exposure prophylaxis (PrEP) lives up to the hype, a study recently completed in England, the PROUD study, should dispel concerns. It set out to determine whether the excitement surrounding PrEP is, in fact, warranted.

"We wanted to determine whether PrEP would work in the real world in clinic settings," said Dr. Sheena McCormack, professor of clinical epidemiology at the MRC Clinical Trials Unit at University College London, and chief investigator of the PROUD study.

Dr. McCormack discussed the results of the study at the 2015 Conference on Retroviruses and Opportunistic Infections (CROI 2015) in Seattle earlier this year.

Questions Surrounding PrEP

Although there is no doubt that PrEP represents an advance in the prevention of HIV/AIDS, there are a number of reasons that some people question its overall effectiveness:

* Those at risk of HIV infection must take PrEP regularly. In order for PrEP to work, it has to be taken consistently. The Centers for Disease Control and Prevention recommends that PrEP be taken daily in order to get the maximum benefit of the biomedical treatment. Jonathan Mermin, M.D., MPH, director of the National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, has pointed out that getting people to take PrEP every day has been challenging.

* People taking PrEP might engage in riskier behavior. Some have wondered whether people taking PrEP might stop using condoms regularly, since PrEP lowers their risk of becoming infected with HIV. The problem with decreasing condom usage is that it would increase one's risk of becoming infected with other sexually transmitted infections (STIs). So although PrEP could lead to a decrease in HIV, some wonder whether it could indirectly lead to an increase in other STIs.

* Clinics might have difficulties administering PrEP. Another concern surrounding PrEP is whether it's realistic to expect sexual-health clinics to be able to administer it along with their other duties.

Measuring the Results

Launched in 2012, the PROUD study enrolled 545 MSM. Thirteen sexual-health clinics in England also participated in the study. Participants were broken up into two groups. The first group of 276 MSM were given PrEP immediately, while the other 269 were given PrEP a year later. Both groups also received the same education about safer sex and condom usage and were tested for STIs.

During the first year of the study, 22 HIV infections occurred among participants. Nineteen of the infections came from the group that had not started taking PrEP. Only three of the members of the group taking PrEP became infected. In examining the results, researchers concluded that taking PrEP reduced the risk of HIV infection by 86 percent.

When it came to condom usage, the study found that MSM who were on PrEP were not less likely to use condoms than those who were not taking PrEP. Not only that, but PrEP users were also not more likely than non-PrEP users to be diagnosed with other STIs.

The clinics that participated in the PROUD study were also able to successfully administer PrEP while continuing their other HIV-prevention strategies.

The findings were particularly exciting for researchers because Public Health England, one of the study's organizers, estimates that there are more than 2,500 new HIV infections each year among gay men in the United Kingdom, a number that has not fallen in the last 10 years. PrEP could help cut that number down dramatically.

Likewise, the results can be applied in the United States, where the same questions exist about PrEP's effectiveness as a practical tool. "The research presented at [CROI 2015] continues to support the power of PrEP to prevent HIV infections," Dr. Mermin said during an interview at the conference.

The PROUD-study researchers agree. "Our concerns that PrEP would be less effective in the real world were unfounded," Dr. McCormack said.

Tamara E. Holmes is a Washington, D.C.-based journalist who writes about health, wealth and personal growth.