<b><i>Introduction:</i></b> The Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP) delivered in a group format could facilitate the implementation of evidence-based psychological treatments. <b><i>Objective:</i></b> This study compared the efficacy of group UP and diagnosis-specific cognitive behavioral therapy (dCBT) for anxiety and depression in outpatient mental health services. <b><i>Methods:</i></b> In this pragmatic, multi-center, single-blinded, non-inferiority, randomized controlled trial (RCT), we assigned 291 patients with major depressive disorder, social anxiety disorder, panic disorder, or agoraphobia to 14 weekly sessions in mixed-diagnosis UP or single-diagnosis dCBT groups. The primary test was non-inferiority, using a priori criteria, on the World Health Organisation 5 Well-Being Index (WHO-5) at the end of the treatment. Secondary outcomes were functioning and symptoms. We assessed outcomes at baseline, end-of-treatment, and at a 6-month follow-up. A modified per-protocol analysis was performed. <b><i>Results:</i></b> At end-of-treatment, WHO-5 mean scores for patients in UP (<i>n</i> = 148) were non-inferior to those of patients in dCBT (<i>n</i> = 143; mean difference –2.94; 95% CI –8.10 to 2.21). Results were inconclusive for the WHO-5 at the 6-month follow-up. Results for secondary outcomes were non-inferior at end-of-treatment and the 6-month follow-up. Client satisfaction and rates of attrition, response, remission, and deterioration were similar across conditions. <b><i>Conclusions:</i></b> This RCT demonstrated non-inferior acute-phase outcomes of group-delivered UP compared with dCBT for major depressive disorder, social anxiety disorder, panic disorder, and agoraphobia in outpatient mental health services. The long-term effects of UP on well-being need further investigation. If study findings are replicated, UP should be considered a viable alternative to dCBT for common anxiety disorders and depression in outpatient mental health services.

Comorbidity among the anxiety disorders is common and may negatively impact treatment outcome. Potentially, transdiagnostic cognitive-behavioral treatments (CBT) deal more effectively with comorbidity than standard CBT. The present study tested the effectiveness of The Unified Protocol (UP) applied to Mental Health Services. Pre-post-treatment effects were examined for psychiatric outpatients with anxiety disorders receiving UP treatment in groups. Forty-seven patients (mean-age = 34.1 (SD = 9.92), 77% females) with a principal diagnosis of anxiety were included. We found significant and clinically meaningful changes in the primary outcomes Clinical Global Impression Severity Scale (CGI-S; d = 1.36), Hamilton Anxiety Scale (HARS; d = .71), and WHO-5 Well-being Index (WHO-5; d = .54). Also, comorbid depressive symptoms and levels of positive and negative affect changed significantly after treatment. Patients with high levels of comorbidity profited as much as patients with less comorbidity; however, these patients had higher scores after treatment due to higher symptom burden at onset. Patients with comorbid depression profited more from treatment than patients without comorbid depression. The treatment effects found in the present study correspond to treatment effects of other TCBT studies, other UP group studies, and effectiveness studies on standard CBT for outpatients. The results indicate that the UP can be successfully applied to a MHS group setting, demonstrating positive effects on anxiety and depressive symptoms for even highly comorbid cases.

Our findings elaborate on previous findings and are in line with recent neurological findings suggesting that disgust and insular impairments are associated with AN. Clinical implications of our findings are discussed.