Condom effectiveness in reducing heterosexual HIV transmission: a systematic review and meta-analysis of studies on HIV serodiscordant couples

Objective: This systematic review and meta-analysis aimed to reassess the effectiveness of condoms in reducing heterosexual transmission of HIV. Methods: Medline, Scopus, and the ISI Web of Science databases were searched up to June 2014. Eligible studies were synthesized using random-effects models. Results: Twenty-five studies with 10,676 HIV serodiscordant heterosexual couples were analyzed. The risk of HIV transmission was considerably lower among couples that were always using condoms compared to never-users (RR:0.29, 95% CI: 0.20-0.43) or inconsistent users (RR: 0.23, 0.13-0.40). The protective effect was slightly higher when the male rather than the female partner was infected (RR:0.31, 0.20-0.48; vs. RR:0.44, 0.24-0.80), and very high in Asian settings (RR:0.06, 0.01-0.46). Conclusions: Though imperfect, condoms reduce HIV transmission by more than 70% when used consistently by HIV serodiscordant heterosexual couples. Social, cultural and biological differences need to be studied further to inform projection modelers and policy makers.