Gender and ethnic disparities of HIV and syphilis seroconversions in a 4-year cohort of injection drug users.

This study assessed gender and ethnic disparities of HIV and syphilis seroconversions in a cohort of injection drug users (IDUs) in Southwest China. A cohort of HIV-seronegative IDUs was followed up from November 2002 to January 2007. The average seroincidence for HIV and syphilis was 2.2 and 4.2 per 100 person-years (PYs), respectively. Multivariable Poisson regression models indicated that the predictors for incident HIV seroconversion included non-Han minority ethnic groups (RR: 5.2; 95% CI: 1.9-14.4) and injecting drugs > or = 7 times/week in the past 3 months (RR: 3.6; 95% CI: 1.4-9.8). The predictors for incident syphilis seroconversion included female (RR: 4.1; 95% CI: 1.8-9.3) and being married or cohabiting (RR: 2.7; 95% CI: 1.2-5.9). These findings suggested that HIV continues to spread among IDUs, especially among Yi and other minority ethnic groups, and frequent risky injections might be the major diver of the epidemic. Female IDUs are disproportionally affected by syphilis. Further research is needed to better understand the ethnicity disparity for HIV and gender disparity for syphilis.