Changes in bacterial sexually transmitted infections among men who have sex with men using pre-exposure prophylaxis in West Java, Indonesia.

BackgroundWe assessed STI incidence, prevalence, and associated factors, and changes in sexual behaviours among MSM using HIV pre-exposure prophylaxis (PrEP) in West Java province, Indonesia.MethodsThe Indonesia PrEP pilot program was a prospective, real-world implementation study providing oral daily or event-driven PrEP among key populations (KPs) in Indonesia. Participants completed baseline and three-monthly follow-up visits between 2021 and 2023, providing data on HIV tests, sexual behaviours, and changes in STIs.Results311 MSM were included in the analyses (median age 26.95, 54.34% chose D-PrEP, 16.40% had a history of STIs). During follow-up, STI prevalence increased, from 8.57% at month-three (M3) to 12.5% at M12. The STI incidence rate was 15.4/100 person-years [PYs] (9.78-23.16; 23 new STIs over 149 PYs). Multiple sexual partners and condomless last sex decreased, while inconsistent condom use increased. History of STIs before PrEP initiation (age-adjusted odds ratio [aOR] 5.02, 2.21-11.39, p < 0.001), condom use at last sex (aOR 3.24, 1.07-9.80, p = 0.037), and not having ≥2 sexual partners (aOR 0.12, 0.03-0.47, p = 0.002) were associated with STIs.ConclusionsAmong MSM in West Java, an increase in the prevalence of STIs was observed, but not exceeding the prevalence before PrEP initiation, which was related to sexual behaviours.