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Correlation between HIV, rectal gonorrhea could help PrEP trial designs

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February 11, 2019

Study findings showed a correlation between the incidence of rectal gonorrhea and HIV infection among men who have sex with men who are not using pre-exposure prophylaxis, or PrEP, for HIV prevention. Researchers said the finding demonstrates that rectal gonorrhea incidence may serve as a potential predictor of HIV incidence, which could inform future HIV prevention trials.

“Our article is a potential proof-of-concept of the relationship between HIV incidence and rectal gonorrhea incidence in men who have sex with men (MSM) based on a simple literature search,” Jeffrey S. Murray, MD, MPH, deputy director of the FDA’s Division of Antiviral Products, told Infectious Disease News. “If fully developed, with additional data confirming this finding, one could possibly use this as a drug development tool for HIV prevention trials. It is a tool to estimate what the HIV incidence would have been had trial participants not received PrEP.”

PrEP has been shown to be highly effective in reducing the incidence of HIV — a “tremendous public health accomplishment” that nevertheless “raises challenges for future PrEP efficacy trials,” Murray and colleagues wrote.

In high-risk populations, it is common for HIV and rectal gonorrhea to “travel together,” Murray said. For their study, he and co-author, Charu Mullick, MD, senior medical officer of the FDA’s Division of Antiviral Products, searched available literature in PubMed using the search terms “gonorrhea” and “HIV.” They included only studies published in 2000 or later involving HIV-uninfected MSM not taking PrEP that had available prospective longitudinal incidence for rectal gonorrhea and HIV in the cohort for the same person-years follow-up.

The final analysis included eight studies conducted from 2000 to 2016. Overall, the incidence of rectal gonorrhea ranged from 1.7/100 person-years to 33/100 person-years, whereas the incidence of HIV ranged from 0.9/100 person-years to 9/100 person-years. Mullick and Murray observed a “strong correlation” for rectal gonorrhea and HIV incidence (Pearson correlation = 0.94; 95% CI, 0.68-0.99).

Using the reported HIV and rectal gonorrhea rates from the eight studies, the researchers developed a predictive model for HIV incidence rate, which could potentially be used to predict risky sexual behavior in PrEP trials, according to the study.

“A counterfactual HIV incidence estimate could help in reducing trial sizes in the future or perhaps even allow for single-armed trials,” Murray said. “Our goal in publishing this was to provoke interest in further analyzing associations between [rectal gonorrhea] — and other sexually transmitted infections — and HIV using additional cohorts and in stimulating research in ways to make HIV prevention trials more efficient.” – by Marley Ghizzone

Disclosures: The authors report no relevant financial disclosures.

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