Abstract: Seven studies met our eligibility criteria. All were randomized controlled trials; six assigned clusters and one randomized individuals. Sample sizes for the cluster-randomized trials ranged from 2157 to 15,614; the number of clusters ranged from 18 to 70. Four trials took place in African countries, two in the USA, and one in England. Three were based mainly in schools, two were in community settings, one took place during military training, and one was clinic-based. Five studies provided data on pregnancy, either from pregnancy tests or national records of abortions and live births. Four trials assessed the incidence or prevalence of HIV and HSV-2. Three trials examined other STI. The trials showed or reported no significant difference between study groups for pregnancy or HIV, but favorable effects were evident for some STI. Two showed a lower incidence of HSV-2 for the behavioral-intervention group compared to the usual-care group, with reported adjusted rate ratios (ARR) of 0.65 (95% CI 0.43 to 0.97) and 0.67 (95% CI 0.47 to 0.97), while HIV did not differ significantly. One also reported lower syphilis incidence and gonorrhea prevalence for the behavioral intervention plus STI management compared to the usual-care group. The reported ARR were 0.58 (95% CI 0.35 to 0.96) and 0.28 (95% CI 0.11 to 0.70), respectively. Another study reported a negative effect on gonorrhea for young women in the intervention group versus the control group (ARR 1.93; 95% CI 1.01 to 3.71). The difference occurred among those with only one year of the intervention. We found few studies and little clinical evidence of effectiveness for interventions promoting condom use for dual protection. We did not find favorable results for pregnancy or HIV, and only found some for other STI. The overall quality of evidence was moderate to low; losses to follow up were high. Effective interventions for improving condom use are needed to prevent pregnancy and HIV/STI transmission. Interventions should be feasible for resource-limited settings and tested using valid and reliable outcome measures.

Plain-language summary: Through September 2013, we did computer searches for studies of programs to improve condom use. We wrote to researchers for missing data. The studies could have various designs. The education program addressed preventing pregnancy and HIV/STI. The intervention was compared with a different program, usual care, or no intervention. The studies had a clinical outcome such as pregnancy, HIV, or STI tests. We did not use self-reports of condom use. We found seven randomized trials. Six assigned groups (clusters) and one randomized individuals. Four trials took place in African countries, two in the USA, and one in England. The studies were based in schools, community settings, a clinic, and a military training setting. Five trials examined pregnancy, four studied HIV and HSV-2 (herpes), and three assessed other STI. We found no major differences between study groups for pregnancy or HIV. Some results were seen for STI outcomes. Two studies showed fewer HSV-2 cases with the behavioral program compared to the control group. One also reported fewer cases of syphilis and gonorrhea with the behavioral program plus STI management. Another study reported a higher gonorrhea rate for the intervention group. The researchers believed the result was due to a subgroup that did not have the full program. We found little clinical effect of improving condom use. The studies provided moderate to low quality information. Losses to follow up were high. We need good programs on condom use to prevent pregnancy and HIV/STI. Programs should be useful for settings with few resources. Interventions should be tested with valid outcome measures.