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HIV prevention trial exposes adherence challenge

A close up of Gilead Sciences Inc.'s Truvada pill, an HIV treatment, in a lab in a Foster City, Calif. (AP Photo/Paul Sakuma, File)

Treatments to prevent the spread of HIV are extremely effective, only when people take them correctly.  A new study published in the New England Journal of Medicine produced surprising results when proven treatments against the spread of HIV did not work as well as expected.

The difference between people on the treatment and those using placebos was minimal, it found. That is largely due to the fact that only about 40 percent of the participants were using the treatment as prescribed. The age group that is at highest risk of contracting HIV do not use the treatment that can prevent being infected, found the study. Women under the age of twenty-five were the least likely to take their pre-exposure prophylaxis, when offered.

The study, conducted in sub-Saharan Africa, is a small set-back for the potential of pre-exposure prophylaxis (PrEP) to prevent the spread of HIV/AIDS.

“It was, I would say, a very, very unexpected, sobering, initially incredibly depressing result,” said Jeanne Marrazo, professor of infectious diseases at the University of Washington and the study’s lead author, to VOA.

Marrazo and a cohort of co-authors screened 12,320 women in South Africa, Uganda and Zimbabwe for HIV. Roughly 5,029 of which were enrolled in the study, ranging in ages from 18 to 45. They were then divided into five equal treatment groups that received no or a variant of PrEP treatment – oral tenofovir alone, oral tenofovir with emtricitabine, oral placebo, vaginal tenofovir gel, and vaginal placebo gel.

For those who took the treatment as prescribed, the drugs helped lower infection rates by as much as ninety-two percent. Inconsistent use saw higher rates of infection. Participants were asked if they were following through on treatment and the majority said they were. However, blood tests to detect the drugs showed a different story. Only about one-quarter of the women younger than twenty-five had traceable amounts of the drugs in their systems. Stigma of taking the drug and the need to use it each day were considered significant barriers for young women.

“Many women said things like, ‘Well, you know, if I bring this product home and my boyfriend or my husband sees it on my counter, then they’re going automatically to think I have HIV and that’s it for me,’” explained Marrazo. “Other women said, ‘I really can’t be seen with this because people are going to think I am at risk for HIV, and that’s just not OK.”

Truvada (know by its generic name as tenofovir), a drug developed by Gilead Sciences, captured immediate attention when a study published in 2010 showed it reduced the risk of people contracting HIV by ninety percent. Follow up research on gay men, heterosexual couples and injecting drug users all demonstrated that taking the drug protected non-infected individuals against contracting HIV from their partners. The accolades were immediate.

On the day the N.I.H. announced the results of the PrEP study, the research team received a congratulatory phone call from President Obama. Shortly thereafter, Time put PrEP in the first slot on its list of the year’s top medical innovations.

From the beginning there was some caution about the potential impact of using drugs to prevent the spread of HIV. Among those concerns were behavioral. Marrazo’s study shows that they are to some extent warranted.

Previous studies into the treatments have involved much higher rates of adherence. The new findings further affirm that people who follow through as directed are better protected, but those who don’t are not much better off. What was most surprising is the discrepancy between reported use and the blood tests. Patients even went as far as to hide unused medication from the researchers to show they were complying with the treatment.

“The striking finding in the [Vaginal and Oral Interventions to Control the Epidemic] trial is the disconnect between reported adherence and actual adherence to the regimen,” writes Dr Michael S. Saag in an accompanying commentary to the study. “The question that emerges is this: why did the participants go to such lengths to create the appearance that they were taking medications when they were not?”

Marrazo and her follow authors characterize the surprising findings as a learning opportunity for future research studies and strategies for rolling out PrEP. They call on future research to look closely at motivations for participating in studies and considering the factors that will improve adherence. That is in addition to simply better tracking adherence of study participants.


About Author

Tom Murphy

Tom Murphy is a New Hampshire-based reporter for Humanosphere. Before joining Humanosphere, Tom founded and edited the aid blog A View From the Cave. His work has appeared in Foreign Policy, the Huffington Post, the Guardian, GlobalPost and Christian Science Monitor. He tweets at @viewfromthecave. Contact him at tmurphy[at]