Evidence of syndemic clustering of sexual behaviors among men who have sex with men (MSM) in Hubei Province, China

Sexual behaviors among men who have sex with men (MSM) often occur in interconnected patterns rather than in isolation. This study examined whether condomless sex, group sex, commercial sex, and sexualized drug use (SDU) clustered together in a syndemic pattern among MSM in a populous Chinese province. Using cross-sectional survey data, four behaviors were measured as binary indicators. Pairwise correlations and co-occurrence analyses tested whether behavioral clustering exceeded that expected under statistical independence. We identified two primary clustering patterns: (1) strong synergy between group sex and commercial sex (O/E ratio = 3.72, 95% CI 2.59–5.18), reflecting overlapping network and transactional sexual ecologies; and (2) the co-occurrence of SDU with all three other behaviors, indicating its presence across the behavioral spectrum. These findings demonstrate non-random behavioral clustering consistent with a syndemic framework. Interventions targeting single behaviors may overlook these mutually reinforcing patterns; integrated strategies addressing behavioral syndemics holistically may have greater relevance for MSM sexual health.