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Magical thinking? FEM-PrEP trial may have failed because participants used testing as prevention
Gus Cairns, 2013-07-09 10:30:00
While the 7th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2013) featured news from two trials of pre-exposure prophylaxis (PrEP) that had positive results, it also featured an analysis of the reasons why another trial may have had a negative one.
The FEM-PrEP trial took place in four sites in South Africa, Tanzania and Kenya and enrolled 2120 women aged 18 to 35 who were given either tenofovir (Viread) plus emtricitabine (FTC, Emtriva) as PrEP or a placebo.
Its results, announced in April 2011, were a disappointment as the women allocated to tenofovir/emtricitabine had no fewer HIV infections than the women on placebo. Analysis of drug levels in subjects showed that adherence had been very low: fewer than 40% of the women involved had taken any drug in the 48 hours before a drug test, and only a quarter had taken their pills daily.
While there were also concerns that the injectable contraceptives many participants took may have increased the risk of HIV infection, it looks as if in the main the subjects of the FEM-PrEP trial decided oral PrEP was not for them. And yet retention in the study was excellent: at the end of the trial, 82% of those who started had continued to attend monthly trial visits.
A series of qualitative interviews with a randomly picked 5% of trial participants suggests that women joined the trial for reasons other than PrEP and that the thing they valued especially was having a monthly test for HIV. In addition, they used the test, and participating in the trial itself, as a way of getting reassurance that they did not have HIV. The trial itself, in the minds of the women, became the prevention method offered.
“It’s magical thinking,” presenter Christina Wong of FHI 360, who co-ordinated the trial, commented to aidsmap.com. “We should discuss how to better incorporate participants' reasons for trial participation into trial design,” she said.
Source:1
