HIV Seroconversion and Types of Relationships Among Men Who Have Sex With Men: A Cohort Study in China

Background: The role of partner types in modifying HIV seroconversion risk among men who have sex with men (MSM) is complex. We sought to understand the role of regular sexual partners and risky sexual behavior in contributing to incident HIV infection among MSM. Methods: From July 2011 to August 2017, we recruited HIV-negative men who reported having anal or oral homosexual encounters in the past 6 months and they were followed up every 3 months for 2 visits. We collected sociodemographic and behavioral characteristics by a self-administrated questionnaire. HIV status was confirmed by a sequential rapid test and confirmatory test. We used multivariable Cox regression to identify risk factors and interaction models to evaluate the relative excess risk between relevant variables. Results: Among 1218 participants, the HIV seroconversion rate was 3.66/100 person-years. HIV seroconversion was associated with lower educational attainment [adjusted hazards ratio (aHR)] = 1.73, 95% CI: 1.06 to 2.81), having had penetrative sex with male before age of 18 years (aHR = 2.44, 95% CI: 1.20 to 4.99), not using condoms in the last sexual encounter (aHR = 2.19, 95% CI: 1.29 to 3.71), and having regular but not committed partners (aHR = 3.33, 95% CI: 1.77 to 6.93). Among 890 (73%) of men reported having regular partners, HIV seroconversion was more frequent in men whose stable partners were not committed as boyfriends (aHR = 3.31, 95% CI: 1.73 to 6.36) and in men having unprotected anal sex (aHR = 2.61, 95% CI: 1.42 to 4.80). Interaction between these 2 factors was observed (relative excess risk of interaction = 4.53). Conclusions: Incidence among MSM in China was high; unprotected sex with steady but not committed partners was associated with increased seroconversion risk. It is imperative to expand safer sex education and training for MSM to reduce unsafe sexual behaviors, including awareness that casual partners are not the only source of infection.