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  Reported by Jules Levin
IDWeek Oct 26-30
New Orleans 2016
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Meta-Analysis Sees Much Higher STI Risk in MSM On vs Not On PrEP
  IDWeek 2016, October 26-30, 2016, New Orleans
Mark Mascolini
Men who have sex with men (MSM) using PrEP had up to 45-fold higher rates of three common sexually transmitted infections (STIs) in a meta-analysis of 18 cohort studies comparing MSM PrEP users with MSM not on PrEP [1]. University of California, Los Angeles (UCLA) researchers believe their findings justify quarterly STI screening for MSM on PrEP.
Daily or as-needed pre-exposure prophylaxis (PrEP) with tenofovir/emtricitabine (TDF/FTC) protects high-risk groups including MSM from picking up HIV infection. Incidence (new diagnoses) of STIs ran high in PrEP trials, but the magnitude of that risk remains uncertain, especially compared with similar high-risk people not using PrEP. The UCLA team conducted this meta-analysis to determine whether PrEP is linked to higher STI risk in MSM on PrEP versus those not on PrEP.
The UCLA team reviewed the English-language literature to identify studies through March 2016 that used nucleic acid amplification to calculate incidence of three STIs in MSM--any Neisseria gonorrhoeae (NG) infection, any Chlamydia trachomatis (CT) infection, and syphilis infection. Eighteen studies met inclusion criteria. For MSM given PrEP, there were 4 studies of NG, 4 of CT, and 5 of syphilis. For MSM not given PrEP, there were 5 studies of NG, 6 of CT, and 11 of syphilis.
The analysis involved more than 70,000 person-years of follow-up in 18 cohort studies. Among MSM using PrEP, incidence per 100 person-years was 37.5 for NG, 38.0 for CT, and 14.5 for syphilis. Respective incidence rates for MSM not using PrEP were 4.2, 6.6, and 0.9.
Comparing incidence in MSM on versus off PrEP, the investigators calculated a 25 times higher rate of NG (incidence rate ratio [IRR] 25.3, 95% confidence interval [CI] 22.6 to 28.4, P < 0.001), an 11 times higher rate of CT (IRR 11.2, 95% CI 10.2 to 12.3, P < 0.001), and a 45 times higher rate of syphilis (IRR 44.6, 95% CI 39.1 to 51.1, P < 0.001).
The researchers noted that higher STI rates in MSM on PrEP could reflect less condom use, more sex partners, and/or increased STI detection in MSM with closer follow-up because they used PrEP. The UCLA team believes their findings support revising the CDC advice to recommend quarterly STI screening for MSM on PrEP--instead of the current advice to screen twice yearly to quarterly.
The investigators suggested that clinicians "must provide their patients on PrEP with a sexual health prevention package that includes quarterly STI screenings, timely treatment of infection, expedited partner treatment, and rescreening, if positive."
1. Kojima N, Davey DJ, Klausner JD. Meta-analysis finds association between pre-exposure prophylaxis to prevent HIV infection and increased risk of sexually transmitted infection acquisition among men who have sex with men. IDWeek 2016, October 26-30, 2016, New Orleans. Abstract 504.