Pilot Randomized Controlled Trial of the Emotion Detectives In-Out: A Blended Version of the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders in Children

Anxiety disorders are highly prevalent in childhood, and increasing demand for services highlights the need for scalable and accessible interventions. This pilot randomized controlled equivalence trial examined the feasibility and preliminary efficacy of a blended adaptation of the Unified Protocol for Children (“Emotion Detectives In-Out”), integrating face-to-face group sessions with self-guided and therapist-supported online components. The intervention was compared with Coping Cat, a well-established cognitive-behavioral group program for childhood anxiety. Seventy-seven children aged 7–12 years with a primary anxiety disorder were randomized to either condition. Outcomes included clinician-rated severity and improvement, child- and parent-reported anxiety and depressive symptoms, and anxiety-related interference in daily life. Both interventions were associated with significant improvements over time across most outcomes. No significant between-group differences were observed for clinician-rated severity or improvement, and remission and treatment response rates were comparable. Significant group-by-time interaction effects favoring the blended intervention emerged for child-reported generalized anxiety, total anxiety and overall symptom scores. The only significant between-group difference was observed for parent-reported family interference, which was higher in the blended condition at post-treatment. Equivalence analyses indicated comparable outcomes across several primary measures. Findings provide preliminary evidence that a blended transdiagnostic group intervention can achieve clinical outcomes comparable to a gold-standard cognitive-behavioral program while offering potential advantages in scalability and accessibility. Larger, fully powered trials with follow-up assessments are warranted to confirm these results and evaluate long-term effectiveness. Trial registration number: 10.17605/OSF.IO/62N4X (retrospectively registered at November 18, 2025). (At the time the study commenced, prospective registration was not required by the institutional ethics procedures and the authors were unaware of the registration requirement. The trial was registered once this requirement became known.)