Background and Goal: Pre-exposure prophylaxis (PrEP) is a preventive medicine that reduces the risk of contracting HIV. There is concern that PrEP use may be associated with an increase in bacterial sexually transmitted infections (STIs) like gonorrhea, chlamydia, and syphilis among men who are gay or bisexual. This study explored the relationship between PrEP use and the rates of bacterial STIs over time.
Study Approach: Researchers used data from the iCruise Study, an online longitudinal study of men who are gay or bisexual or have sex with men, in Ontario from July 2017 to April 2018. The study examined how PrEP use related to the number of self-reported bacterial STIs. Researchers analyzed results from 535 participants who completed a weekly diary survey for up to a three-month study period. The study measured the number of chlamydia, gonorrhea, and syphilis infections per 100 months of participant observation time.
Main Results:
- 535 participants in the iCruise Study were included in the analysis. Researchers followed participants for a total of 1,623.5 person-months (total time all participants were in the study). About 13.1% (70 participants) reported using PrEP during the study period.
- PrEP use was linked to a higher rate of gonorrhea:
- The initial analysis suggested that the rate of gonorrhea among PrEP users was four times higher than among non-users., with an incidence rate ratio of 4.00. After conducting a bias analysis to account for potential inaccuracies in self-reported data, the association was less pronounced, with a median incidence rate ratio of 2.36 among PrEP users.
- There was no significant increase in the rates of chlamydia or syphilis among PrEP users.
Why It Matters: Individuals who take PrEP are at higher risk for gonorrhea and should be regularly tested and treated to manage this risk effectively. This study highlights the importance of STI testing, risk reduction, and secondary prevention measures.
Self-Reported PrEP Use and Risk of Bacterial STIs Among Ontarian Men Who Are Gay or Bisexual or Have Sex With Men
Nguyen K. Tran, PhD, MPH, et al
Stanford University School of Medicine, Palo Alto, California
Department of Epidemiology and Biostatistics, Drexel University Dornsife School of Public Health, Philadelphia, Pennsylvania
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