Dramatic Reductions in Rates of HIV Transmission in Two Real-World PrEP Studies
Christopher Hoffmann, MD, MPH, Johns Hopkins University School of Medicine
In the past month, 2 dramatic real-world type studies on pre-exposure prophylaxis (PrEP) using daily tenofovir/emtricitabine (Truvada brand) were published. One study was a pragmatic randomized clinical trial based in sexual health clinics in England, the PROUD study [ McCormack, et al. Lancet. 2015 Sept. 9], and the other was an observational study from routine clinical data in the San Francisco Kaiser Permanente healthcare system [ Volk JE, et al. CID. 2015 Sept. 1]. Both studies reported remarkably low rates of HIV transmission among patients over the first 12 months of receiving PrEP. In the PROUD study, 3 of the 275 participants in the PrEP arm seroconverted, for a rate of 1.2 per 100 person-years (although the authors suggest it is unlikely that the seroconverters were actually taking PrEP), compared to 20 of the 269 patients in the control arm, for a rate of 9 per 100 person-years. This represents an 86% reduction in HIV incidence. In the Kaiser Permanente study, no seroconversions occurred over 12 months among the 657 PrEP initiators. Had the incidence been comparable to the PROUD control arm, 34 seroconversions would have been expected.
Notably, in both studies, the patients had substantial HIV risk as reflected by high rates of incident sexually transmitted infections (STIs). In the PROUD study, 54% were diagnosed with an STI over 12 months of observation, and in the Kaiser Permanente study, 30% were diagnosed with an STI during the first 6 months of PrEP use. Rectal infection was most common in both studies, further pointing to high risk for HIV acquisition.
Both studies suggest a real-world effectiveness that exceeds the efficacy results from the initial placebo-controlled clinical trials. Both of these studies strongly support accelerating the rollout of PrEP and confirm that all non-HIV-infected men who have sex with men who have been diagnosed with an STI in the past 6 or 12 months or who report multiple sexual partners should be offered PrEP.
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