Incidence, recurrence, and determinants of sexually transmitted infections among people with HIV: a multicenter cohort study in China, 2010-2024, with implications for integrated HIV-STI prevention across the Western Pacific.

Background: Sexually transmitted infections (STIs) remain a major public health concern among people with HIV (PWH) in the Western Pacific region, where systematic long-term surveillance is limited. As the region's largest epidemic country, China has yet to generate longitudinal evidence on STI burden, recurrence, and risk determinants, emphasizing the urgency of integrated monitoring within HIV care systems. Methods: We established a multicenter dynamic cohort including 32,961 PWH who initiated ART between 2010 and 2024 at two major HIV treatment centers in southern China. Five major STIs-syphilis, human papillomavirus (HPV), herpes simplex virus type 2 (HSV-2), gonorrhea, and chlamydia-were identified through linked clinical and laboratory records. Annual incidence rates were calculated, cumulative incidence was estimated using the Aalen-Johansen method, and demographic and clinical determinants were assessed using Fine-Gray models. Recurrence of viral infections and reinfection of bacterial STIs were identified by repeated laboratory-confirmed diagnoses during follow-up. Findings: From 2010 to 2024, 14.1% of participants experienced at least one STI after ART initiation, with the overall incidence of any STI increasing from 7.7 (95% CI 3.3-15.2) to 28.3 (95% CI 26.1-30.6) per 1000 person-years. Syphilis remained the leading infection, showing two distinct peaks in 2018 and 2024. HPV ranked second, with incidence rising steadily until 2021 before a modest decline. Gonorrhea and chlamydia resurged around 2022, while HSV-2 remained at a low but stable level. Younger age, male sex, and men who have sex with men were independent predictors of any STI. Higher baseline CD4 Interpretation: This long-term multicenter cohort provides the most comprehensive evidence to date on STI epidemiology among people with HIV in China. It reveals a persistently high burden of syphilis and HPV, a sharp resurgence of bacterial STIs, and notable recurrence of viral infections. These findings underscore the importance of strengthening comprehensive STI prevention and monitoring within HIV care settings, particularly through systematic screening and sustained surveillance efforts. By offering regionally relevant data, this study informs integrated HIV-STI control strategies and advances health equity across the Western Pacific. Funding: National Natural Science Foundation of China; the Guangxi Key Research and Development Program; the Guangdong Basic and Applied Basic Research Foundation; and the Guangdong Provincial Medical Science and Technology Research Fund Project.