Methodological quality in randomised clinical trials of mental health apps: systematic review and longitudinal analysis.

QUESTION This study investigated the methodological rigour of randomised controlled trials (RCTs) of mental health apps for depression and anxiety, and whether quality has improved over time. STUDY SELECTION AND ANALYSIS RCTs were drawn from the most recent meta-analysis of mental health apps for depression and anxiety symptoms. 20 indicators of study quality were coded, encompassing risk of bias, participant diversity, study design features and app accessibility measures. Regression models tested associations between year of publication and each quality indicator. FINDINGS 176 RCTs conducted between 2011 and 2023 were included. Methodological concerns were common for several quality indicators (eg, <20% were replication trials, <35% of trials reported adverse events). Regression models revealed only three significant changes over time: an increase in preregistration (OR=1.27; 95% CI 1.10, 1.46) and reporting of adverse events (OR=1.32; 95% CI 1.11, 1.56), and a decrease in apps reported to be compatible with iOS and/or Android (OR=0.78; 95% CI 0.64, 0.96). Results were unchanged when excluding outliers. Results were similar when excluding three high-quality studies published between 2011 and 2013, with additional evidence for an increase in modern missing data methods (OR=1.22; 95% CI 1.04, 1.42) and studies reporting intention-to-treat analysis (OR=1.20; 95% CI 1.03, 1.39). CONCLUSIONS Findings provide minimal evidence of improvements in the quality of clinical trials of mental health apps, highlighting the need for higher methodological standards in future research to ensure the reliability and generalisability of evidence for these digital tools.