Examining the theory-effectiveness hypothesis: A systematic review of systematic reviews.

Theory-based interventions as currently operationalized in systematic reviews were not found to be more effective than non-theory-based interventions. Methodological and reporting issues at study and review level may not reflect the true utility of theory use within health behaviour interventions. The promotion of theory use may benefit from using a multifaceted argument, rather than a narrow focus of increased effectiveness. Statement of contribution What is already known on this subject? Theory use is regularly promoted by claiming that it will lead to more effective behaviour change interventions. Theory use has been frequently linked to effectiveness within systematic reviews of behaviour change interventions. The theory-effectiveness hypothesis has not been systematically examined at the systematic review level. What does this study add? Theory use as operationalized by systematic review authors was not associated with increased effectiveness within systematic reviews examining randomized controlled trials of behaviour change interventions in adults. Interventions based on control theory, motivational interviewing, or self-determination theory were associated with greater effectiveness for physical activity and/or dietary interventions and outcomes. Theory use should be promoted using a multifaceted argument, and assertions for increased effectiveness of theory-based interventions should only be used in domains where specific evidence exists to support this claim.