Moderators of cognitive and behaviour therapies for prevention and treatment of anxiety disorders in children and adolescents: A systematic review and meta-analysis.

Previous studies have indicated wide variation in the effectiveness of cognitive and behaviour therapies (CBTs) for preventing and treating anxiety disorders in children and adolescents, indicating the presence of moderators influencing outcomes. This meta-analysis investigated whether sample characteristics (child age, child baseline anxiety levels, parental baseline anxiety levels) and intervention characteristics (intervention duration, facilitator contact time, facilitator background, delivery formats, parental involvement) moderate the effectiveness of CBTs for universal prevention, targeted prevention, and treatment of anxiety disorders in children and adolescents. We identified 86 eligible randomized controlled trials (RCTs) assessing the effectiveness of 98 CBTs versus non-active controls. Effect sizes were the post-intervention standardized mean difference of children's broad anxiety symptoms between CBT and non-active controls. Moderation analyses were conducted separately on child- and parent-reported outcomes using meta-regression and subgroup analyses. We found some evidence for (1) a moderating role of child age, facilitator background, and parental involvement on the effectiveness of CBTs for universal prevention; (2) a moderating role of child age and intervention duration on the effectiveness of CBTs for targeted prevention; (3) a moderating role of child age, facilitator contact time, and delivery formats on the effectiveness of CBTs for treatment. There was no evidence for a moderating role of child baseline anxiety levels on the effectiveness of CBTs for universal/targeted prevention or treatment. The moderating role of parental baseline anxiety levels and its potential interaction with parental involvement was not tested given the limited available data. Although these findings provide insights into the question of what works for whom, they should be interpreted cautiously given the limited available data, wide variation in outcomes, potential confounders, and discrepancies between child- and parent-reported outcomes.