Abstract
BACKGROUND: While pre-exposure prophylaxis (PrEP) can prevent HIV acquisition, associated behavioral changes may increase risk of acquiring other sexually transmitted infections (STIs). METHODS: The prospective multicenter BRAHMS study enrolled men who were HIV negative, had sex with men, and were aged 18 to 55 years and reported an increased risk to acquire STI. At 3-month intervals for up to 12 months, participants answered questionnaires and underwent site-specific screening for Chlamydia trachomatis (CT), Mycoplasma genitalium (MG), Neisseria gonorrhoeae (NG), and syphilis. We computed 3-month incidence rates and rate ratios, and we employed multilevel mixed effects logistic regression to determine odds ratios (ORs) and 95% CIs for factors associated with any incident STI. RESULTS: The mean age of 1017 participants was 33 years, 54.7% used PrEP at enrollment, and 83.7% reported PrEP use overall. Any STI was diagnosed in 71.8% (CT, 40.4%; MG, 38.5%; NG, 36.0%; syphilis, 10.1%; HIV, 0.5%). PrEP users exhibited a higher prevalence for anorectal infections with CT (35.3% vs 20.5%, P < .05), MG (31.4% vs 23.5%, P < .05), and NG (26.1% vs 16.9%, P < .05). CT incidence decreased from 46.8 cases per 100 person-years to 35.7 (-23.7%, P < .05), and NG incidence decreased from 41.6 cases per 100 person-years to 30.7 (-26.2%, P < .05). MG and syphilis incidence remained stable. Factors independently associated with STI incidence were as follows: symptoms (OR, 1.85; 95% CI, 1.46-2.34), condomless anal sex with >5 casual partners (OR, 1.79; 95% CI, 1.49-2.14), recreational drug use (OR, 1.76; 95% CI, 1.46-2.12), being born abroad (OR, 1.49; 95% CI, 1.19-1.87), PrEP use (OR, 1.29; 95% CI, 1.05-1.58), and having a moderately or largely increased self-perceived risk of HIV (OR, 1.26 [95% CI, 1.03-1.53]; OR, 1.33 [95% CI, 1.02-1.74], respectively). CONCLUSIONS: PrEP use was associated with increased STI risk in our cohort. CT and NG incidence decreased in a structured test-and-treat setting.