Objectives The current study was conducted to synthesise evaluations of couple-based HIV prevention interventions, assess the efficacy of these interventions in reducing sexual risk, and identify moderators of intervention efficacy.

Methods A comprehensive literature search identified 29 interventions (22 reports; N=5168 couples) that met the inclusion criteria, including enrolment of both members of a heterosexual couple, measurement of condom use at baseline and follow-up, and sufficient statistical information to calculate effect sizes. Effect sizes were analysed using fixed-effects and random-effects assumptions; factors related to intervention efficacy were identified using metaregression.

Results Overall, there were significant increases in condom use from baseline to follow-up (d₊=0.78, 95% CI 0.48 to 1.09) and significant decreases in partner concurrency (d₊=0.37, 95% CI 0.13 to 0.60). Condom use increased to a greater extent when studies were conducted toward the beginning of the epidemic, were located in countries scoring lower on the Human Development Index, enrolled serodiscordant couples, and delivered intervention content in multiple contexts. Couples who had been together longer, reported higher incidence of sexually transmitted infection, were provided voluntary counselling and testing, and provided outcome measures during face-to-face interviews also reported larger increases in condom use.

Conclusions Couple-based interventions are efficacious in reducing unprotected sex within the context of romantic relationships. Future research should continue to improve risk reduction for couples.