Beyond protection: navigating biomedical HIV prevention and risk compensation in MSM, 2018-2024

Men who have sex with men (MSM) face a disproportionately high HIV risk globally. Biomedical prevention strategies, including pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP), reduce HIV transmission, but their combined impact on sexual risk behaviors remains uncertain, raising concerns about risk compensation.

From 2018 to 2024, MSM in Tianjin, China were recruited through snowball sampling and followed within a longitudinal cohort linked to routine HIV testing services. HIV testing frequency and HIV incidence were analyzed using Poisson regression and Cox proportional hazards models, respectively. Unprotected anal intercourse (UAI) risk scores were constructed from sexual behavior indicators. Mixed-effects models and trajectory modeling assessed the associations between biomedical intervention use and UAI risk.

Among 8790 repeat-testing MSM, 1858 (21.14%) used biomedical interventions. Intervention users had lower HIV incidence (0.40 vs. 0.62 per 100 person-years; HR = 0.53, 95% CI 0.35-0.80), more frequent testing (IRR = 1.30, 95% CI 1.27-1.33), higher risk scores (β = 0.191, 95% CI 0.162-0.219), more anal intercourse, and lower condom use at last sex and consistently. Trajectory analysis indicated users were more likely in high-risk group. Risk compensation effects tended to be greater among older MSM and those living in suburban areas.

Biomedical interventions are associated with increased HIV testing and reduced incidence but may elevate UAI risk, especially in older and suburban MSM. Integrating behavioral support into biomedical prevention is essential to mitigate risk compensation and address the prevention paradox in key subgroups.