Efficacy of the Unified Protocol: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The Unified Protocol (UP) pioneered a transdiagnostic cognitive behavioral therapy (CBT) that is widely disseminated because it efficiently treats common and costly internalizing disorders. Our systematic review and meta-analysis improve on three previous systematic reviews of the UP: (a) a nonempirical narrative synthesis; (b) a meta-analysis largely composed of quasi-experimental studies; and (c) another meta-analysis that includes incommensurate sample types. This is the first study that focuses on randomized controlled trials (RCTs) to provide a more reliable causal link between the UP and improved internalizing symptoms. We evaluated outcomes relevant to internalizing disorders: anxiety, depression, and Neuroticism/Negative Affect (N/NA). Findings showed that the UP outperformed comparators, with large effect sizes (baseline to end of treatment [BL to ET]) for anxiety and depression but more moderate for N/NA. A subset of studies with short-term follow-up (FU) data showed stable effect sizes. For anxiety and depressive outcomes, the UP surpassed waitlist control (WLC) and treatment-as-usual comparators, which ranged from equivalent to modestly better than traditional CBT. The moderator that explained between-study heterogeneity for the outcome of depression was the number of therapy sessions, while for the outcome of anxiety, it was the study's quality. Overall, these results offer support for UP as an evidence-based, efficacious psychotherapy for comorbid internalizing disorders. We offer recommendations to improve future UP treatment outcome research. This study's protocol is registered on .