Are universal digital mental health interventions effective for promoting mental health outcomes among children and adolescents? A meta-analysis of effects and moderators

Introduction
Universal digital mental health interventions (DMHIs) are emerging as a viable approach to promoting mental health among children and adolescents in general population. However, there is a scarcity of meta-analyses that examined their short- and long-term effects or potential moderators in individuals aged 19 or younger.

Methods
A systematic search was conducted to identify randomised controlled trials that delivered universal DMHIs for promoting mental health, targeting children and adolescents aged 19 or younger in general population. Meta-analysis was performed to identify studies using Comprehensive Meta-Analysis.

Results
The meta-analysis of 29 included studies identified significant overall effects (g = 0.16) as well as significant effects for anxiety (g = 0.09), depression (g = 0.06), psychological distress (g = 0.28), externalising problem (g = 0.21), psychological well-being (g = 0.19), interpersonal functioning (g = 0.21) and social-emotional skills (g = 0.19) at post-intervention. The analysis of 7 studies that followed up 6 months or longer revealed a significant overall effect (g = 0.09) as well as significant effects for anxiety (g = 0.11) and depression (g = 0.05) at follow-up. Age and intervention duration moderated the overall effects. Gamification moderated the effect on depression. Attrition rate moderated the effect on social-emotional skills.

Conclusions
Providing universal DMHIs with longer durations to younger children may be critical for effectively improving a range of mental health outcomes among children and adolescents. To promote engagement and effectiveness, future studies may explore how gamification and other features for reducing attrition could be effectively incorporated into DMHIs.