Transdiagnostic psychological interventions for emotional disorders: A comprehensive meta-analysis

Previous meta-analyses have integrated evidence on the effects of transdiagnostic interventions for depression and anxiety symptoms. Nevertheless, no recent study covers all types of transdiagnostic interventions administered through a wide range of delivery formats, and targeting participants with different emotional disorders (i.e., mixed samples with different anxiety disorders or mixed depression/anxiety symptomatology). We used the most recent available searches (1st January 2024) of the Metapsy meta-analytic project of randomized trials on psychotherapy for depression and anxiety to identify studies comparing an intervention targeting at least two emotional disorders with a control group (waitlist, usual care, other non-active control). We conducted random-effects meta-analyses of 94 trials (108 comparisons between a psychotherapy and a control group) with 12,443 patients (who have at least a principal diagnosis of anxiety and/or unipolar depressive disorder, or a score above a cut-off point on an anxiety or depression validated self-report scale), to examine the effects on depression and anxiety symptomatology at post-treatment. The overall effect size of the pooled outcomes of depression and anxiety was g = 0.59 (95 % CI 0.50-0.68), with high heterogeneity (I² = 78.88; 95 % CI 74.8-82.3) and a broad prediction interval (-0.18-1.37). The effects remained comparable after a series of sensitivity analyses, including multilevel analyses, exclusion of outliers, adjustment for risk of bias, and adjustment for publication bias. The results were also comparable for depression and anxiety symptoms when considered separately (effect sizes ranged from g = 0.54 to 0.61). However, when considering the impact on anxiety symptoms in studies focusing exclusively on participants with several anxiety disorders, the effects were somewhat larger (g = 0.87). A significantly higher risk of study dropout was found in the intervention conditions compared to the control groups. Transdiagnostic interventions are probably effective at post-treatment for adults with depression and/or anxiety.