Are females who inject drugs at higher risk for HIV infection than males who inject drugs: A meta-analysis from 14 high seroprevalence countries

Objective: There are several reasons females who inject drugs may be at higher risk for HIV compared to male injectors: 1) females may have more difficulties obtaining sterile injection equipment, 2) females may be more likely to inject after males in group settings, and 3) females are more susceptible to sexual transmission. We conducted a systematic review/meta-analysis to assess the extent to which females have higher HIV prevalence than males. Methods: Countries with high seroprevalence (>20%) HIV epidemics among IDUs were identified from the Reference Group to the UN on HIV and Injecting Drug Use. Systematic literature reviews collected data on HIV prevalence by gender. Non-parametric and parametric tests along with meta-analytic techniques examined heterogeneity and differences in odds ratios across studies Results: Data were abstracted from 102 studies in 14 countries with high HIV prevalence; total sample size was 108,986. The mean weighted odds ratio for HIV prevalence among females to males was 1.34, 95% CI 1.03 to 1.90. There was great heterogeneity among studies, I squared = 94.9%. There was a Gaussian distribution of the ln ORs among studies. Conclusion: There is significant evidence for higher HIV prevalence among females than males who inject drugs in high seroprevalence settings. The extreme amount of heterogeneity and the Gaussian distribution suggest multiple causes of differences in HIV prevalence between females and males, with actual outcomes determined by local factors. Special programs to prevent HIV infection among females who inject drugs are clearly needed but should be tailored to local circumstances.