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CROI 2015: PROUD Study of “Real World” PrEP Reports 86% Efficacy

, by Emily Land

BETA is attending and reporting from the 2015 Conference on Retroviruses and Opportunistic Infections this week in Seattle from February 23 to 26—bringing you the latest news, updates, and research on HIV treatment and prevention.


Sheena McCormack

Sheena McCormack, from the Medical Research Council Clinical Trials Unit, presented data from the PROUD study, a “real world” investigation of Truvada-based PrEP’s efficacy, safety, and impact. It was conducted with men who have sex with men and transgender women and was delivered through sexual health clinics in England. The 545 men enrolled were randomized to receive either access to PrEP immediately or in 12 months—although an interim data analysis conducted last fall found PrEP to be “highly effective” and led to all individuals enrolled in the deferred arm being offered immediate access to PrEP.

McCormack reported today that a total of 22 individuals seroconverted during the study, three in the PrEP group and 19 in the deferred group—which corresponds to an estimated 86% reduction in HIV infection risk provided by PrEP. The difference in the rate of HIV infections was “highly significant,” according to McCormack.

The study team believes that some of the individuals diagnosed with HIV during the study—two in the immediate arm and six in the deferred arm—may have actually already been infected with HIV before they were enrolled in the study and/or started taking PrEP. Even taking these individuals out of the equation, McCormack said, “you have one in the immediate [study group], 13 in the deferred [study group], and a very profound difference.”

“Our concerns about PrEP being less effective in the real world were unfounded,” McCormack concluded.

She also reported no evidence of risk compensation—the theory that individuals taking PrEP might actually increase their overall risk of HIV because they compensate for the protection provided by PrEP by increasing other risky behaviors.

Preliminary data analyses, including 349 participant responses, did not show an increase in the number of condomless anal receptive or insertive sex partners at baseline and then after 12 months in either group. “There was still a lot of condom use going on in both groups,” explained McCormack.

Anticipating the argument that condom use is self-reported, and therefore subject to reporting bias, McCormack pointed to STI data as further evidence that overall risk did not increase for PrEP takers.

“You can rely on STIs. When we looked at the rectal infections, there were no significant differences between these two groups.”

STIs were common in both groups, with over 30% experiencing either rectal gonorrhea or chlamydia at some point during the study’s follow-up.

“Really, really effective reduction in HIV without any apparent change in the STIs between groups. We’re PROUD, to share that result with you,” she said at a later press conference.


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