(HealthDay News) — For gay and bisexual men, receipt of HIV preexposure prophylaxis (PrEP) is associated with an increase in sexually transmitted infections (STIs), according to a study published in the Journal of the American Medical Association.

Michael W. Traeger, from the Burnet Institute in Melbourne, Australia, and colleagues describe STI incidence and behavioral risk factors among a cohort of 2981 predominantly gay and bisexual men (98.5%) who use PrEP. Participants received daily oral tenofovir disoproxil fumarate and emtricitabine for HIV PrEP upon enrollment, quarterly HIV and STI testing, and clinical monitoring.

The researchers found that 2928 STIs were diagnosed among 1427 participants (48%) during a mean follow-up of 1.1 years. The incidence of STIs was 91.9 per 100 person-years, with 25% of participants accounting for 76% of all STIs. Younger age, greater partner number, and group sex were associated with greater STI risk, but condom use was not, among 2058 participants with complete data for multivariable analysis. From before enrollment to follow-up, the incidence of STIs increased from 69.5 to 98.4 per 100 person-years (incidence rate ratio [IRR], 1.41). The increase in incidence from one year before enrollment to follow-up was significant for any STI and for chlamydia (adjusted IRRs, 1.12 and 1.17, respectively).

“These findings highlight the importance of frequent STI testing among gay and bisexual men using PrEP,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

References

Traeger MW, Cornelisse VJ, Asselin J, et al.  Association of HIV Preexposure Prophylaxis With Incidence of Sexually Transmitted Infections Among Individuals at High Risk of HIV Infection. JAMA. 2019;321(14):1380-1390. doi:10.1001/jama.2019.2947 

Gandhi M, Spinelli MA, Mayer KH. Addressing the Sexually Transmitted Infection and HIV Syndemic. JAMA. 2019;321(14):1356-1358. doi:10.1001/jama.2019.2945