The incidence of syphilis, HIV and HCV and associated factors in a cohort of men who have sex with men in Nanjing, China

Objective This study investigated the incidence of syphilis, HIV and hepatitis C virus (HCV), as well as factors associated with syphilis seroconversion among men who have sex with men (MSM) in Nanjing, China. Methods A cohort of MSM was recruited by respondent-driven sampling methods. Those who were syphilis-, HIV- and HCV-seronegative at the baseline were invited to be retested at month 6. A Poisson regression analysis was performed. Results Of the 416 participants in the study, 348 participants were HIV-, syphilis-and HCV-negative at the baseline, 250 (71.84%) of whom returned for retesting at month 6. Nine of these 250 participants had seroconverted to syphilis-positive (incidence=7.58 per 100 person-years (PY); 95% CI 2.63 to 12.53 per 100 PY), and five had seroconverted to HIV-positive (incidence=4.17 per 100 PY; 95% CI=0.52 to 7.83 per 100 PY). No HIV and syphilis coinfection and no HCV seroconversion were found. Multivariate analysis identified four statistically significant factors predicting syphilis seroconversion, including currently single marital status (RR=0.32, 95% CI 0.16 to 0.65, p<0.01), monthly income >US$300 (RR=2.68, 95% CI 1.28 to 5.61, p<0.01), self-reported homosexual orientation (RR=0.48, 95% CI 0.24 to 0.96, p<0.05) and recruitment of male sex partners mostly from gay saunas (RR=6.72, 95% CI 2.88 to 15.68, p<0.01). Conclusions The high incidence of syphilis and HIV reflects the seriousness and urgency of the HIV and sexually transmitted diseases (STD) epidemics among MSM in China. Effective interventions of syphilis treatment and prevention should target MSM with characteristics reflecting the aforementioned risk factors.