Objective: The meta-analysis reported here examined interventions informed by the theory of planned behavior (TPB) or theory of reasoned action (TRA) aimed at reducing heterosexual risk behaviors (prevention of STDs and unwanted pregnancy).
Methods: Studies were eligible for inclusion if they were either randomized control trials or quasi-experimental studies that compared the TPB-based intervention against a control group. Search strategy consisted of articles identified in previous reviews, keyword search through search engines, examination of key journals, and contacting key experts.
Results: Forty-seven intervention studies were included in the meta-analysis. Random effects models revealed that pooled effect sizes for TPB-based interventions had small but significant effects on behavior and other secondary outcomes (i.e., knowledge, attitudes, normative beliefs, perceived behavioral control, and intentions). Significant heterogeneity found between effect sizes was explored using metaregression. Larger effects were found for interventions that provided opportunities for social comparison.
Conclusions: The TPB provides a valuable framework for designing interventions to change heterosexual risk behaviors. However, effect sizes varied quite substantially between studies, and further research is needed to explore the reasons why.