The global burden of sexually transmitted infections (STIs) presents a challenge in the context of HIV pre-exposure prophylaxis (PrEP) programmes. We aimed to determine the prevalence and incidence of bacterial STI diagnoses and factors associated with STI incidence among key populations (KPs) initiating PrEP in Indonesia.
The Indonesia PrEP Pilot Programme (December 2021–December 2023), rolled out in 21 districts in 10 provinces, was a prospective, real-world implementation study providing oral daily or event-driven PrEP to KPs (men who have sex with men (MSM), female sex workers, transgender women and people who inject drugs). Participants at 60 healthcare facilities completed baseline and subsequent 3-monthly follow-up visits.
A total of 4220 individuals were included in the analyses (median age 29 (IQR 25–34); 91% men, 81% MSM and 63% chose daily PrEP). The overall STI prevalence was 12.8%; it increased from baseline (10.3%) through month 12 (27.2%) (p<0.001). Among participants with no STIs at baseline (n=3787), 715 new STI diagnoses occurred over 2475 person-years (PYs); the overall incidence rate (IR) was 28.89/100 PYs (27.11–30.72). The highest IR was observed at month 3 (44.71/100 PYs; 41.53–47.93) and decreased over time. Incidence was significantly higher among MSM (age-adjusted IR ratio (aIRR) 2.31; 1.40–3.79 vs FSW), men (aIRR 1.63; 1.10–2.42 vs women), those who reported condomless sex (aIRR 1.67; 1.35–2.06), and those with more frequent sex (aIRR 1.93; 1.47–2.55). Among individuals with complete follow-up (n=464), 48% never acquired STIs during follow-up. The overall HIV incidence rate was 1.11/100 PYs (0.75–1.57); all infections occurred among non-adherent individuals. There were no associations found between HIV incidence and STI diagnoses (p=0.775).
Among KPs using PrEP in Indonesia, the highest STI IR was observed in the early months of implementation. The findings highlight the importance of offering PrEP users regular testing and effective STI counselling.