The explicit use of theory in research helps expand the knowledge base. Theories and models have been used extensively in HIV-prevention research and in interventions for preventing sexually transmitted infections (STIs). The health behavior field uses many theories or models of change. However, educational interventions addressing contraception often have no stated theoretical base.
Review randomized controlled trials that tested a theoretical approach to inform contraceptive choice; encourage contraceptive use; or promote adherence to, or continuation of, a contraceptive regimen.
We searched computerized databases for trials that tested a theory-based intervention for improving contraceptive use (MEDLINE, POPLINE, CENTRAL, PsycINFO, EMBASE, ClinicalTrials.gov, and ICTRP). We also wrote to researchers to find other trials.
Trials tested a theory-based intervention for improving contraceptive use. We excluded trials focused on high-risk groups. Interventions addressed the use of one or more contraceptive methods. The reports provided evidence that the intervention was based on a specific theory or model. The primary outcomes were pregnancy, contraceptive choice, initiating or changing contraceptive use, contraceptive regimen adherence, and contraception continuation.
Data collection and analysis
The primary author evaluated abstracts for eligibility. Two authors extracted data from included studies. We calculated the odds ratio for dichotomous outcomes and the mean difference for continuous data. No meta-analysis was conducted due to intervention differences.
Of 26 trials, 12 interventions addressed contraception (other than condoms), while 14 focused on condom use for preventing HIV or STIs. In 2 of 10 trials with pregnancy or birth data, a theory-based group showed better results. Four of nine trials with contraceptive use (other than condoms) showed better outcomes in an experimental group. For condom use, a theory-based group had favorable results in 14 of 20 trials, but the number was halved in a subgroup analysis. Social Cognitive Theory was the main theoretical basis for 12 trials, and 10 showed positive results. Of the other 14 trials, favorable results were shown for other social cognition models (N=2), motivational interviewing (N=5), and the AIDS Risk Reduction Model (N=2). No major patterns were detected by type of theory, intervention, or target population.
Family planning researchers and practitioners could apply the relevant theories and effective interventions from HIV and STI prevention. More thorough use of single theories would help inform the field about what works. Better reporting is needed on research design and intervention implementation.