Sexually Transmitted Infections on the Rise in PrEP Users

Area of Science:

• Public Health
• Infectious Diseases
• Sexual Health

Background:

• Pre-exposure prophylaxis (PrEP) using oral Truvada is an effective HIV prevention strategy for high-risk homosexual men.
• Concerns exist regarding potential risk compensation or behavioral disinhibition among PrEP users, potentially leading to increased sexually transmitted infections (STIs).
• Previous studies have reported high rates of STIs and condomless sex among PrEP users, with increasing STI rates over time.

Purpose of the Study:

• To investigate the incidence of STIs in HIV-negative homosexual men before and after initiating PrEP.
• To assess changes in STI rates, including gonorrhea, chlamydia, and syphilis, within a cohort of PrEP users.
• To compare STI rates in PrEP users with those who received post-exposure prophylaxis (PEP).

Main Methods:

• A cohort study in Montreal, Canada, measured STI incidence in 109 HIV-seronegative homosexual men over 12 months before and 12 months after starting Truvada for HIV prevention.
• The study tracked new episodes of gonorrhea, chlamydia, and/or syphilis.
• STI rates were compared to a control group of 86 homosexual men who received PEP.

Main Results:

• The incidence of gonorrhea, chlamydia, and/or syphilis significantly increased after the initiation of PrEP.
• The incidence of three or more STIs rose from 3.7 to 9.2 cases per 100 person-years in the PrEP cohort.
• STI rates in PrEP users were higher than in the PEP group, with a notable prevalence of anorectal and asymptomatic infections, often linked to internet-based partner acquisition.

Conclusions:

• Increased STI rates among PrEP users highlight the need for reinforced counseling, diagnosis, and treatment efforts.
• PrEP initiation may facilitate engagement in care for high-risk individuals, offering an opportunity to address STI-related health needs.
• Healthcare providers must adequately inform patients about STIs and the risks associated with multiple or casual sexual contacts while on PrEP.