Systematic Review and Meta-Analyses of Mental Health App RCTs: Persuasive Design, Engagement, and Efficacy

This systematic review and meta-analysis examined the efficacy of digital mental health apps and the impact of persuasive design principles on engagement and clinical outcomes. Of 119 eligible randomised controlled trials, 92 studies (n=16,728) were included in the analysis. Results demonstrated that mental health apps significantly improved clinical outcomes compared to control groups (g = 0.43). Apps used between 1 and 12 persuasive design principles (mode = 5). Notably, only 76% of studies reported engagement data. Twenty-five engagement metrics were identified across studies and grouped into 10 categories. Meta-regression and correlation analyses found no significant association between persuasive design principles and app efficacy or engagement. Future research should prioritise standardising and documenting engagement metrics and persuasive design principles; differentiating between engagement with mental health apps and real-world behavioural change and exploring the integration of persuasive design with behaviour change models to more accurately assess their influence on engagement and outcomes.