Optimizing Outcomes in Psychotherapy for Anxiety Disorders (OPTIMAX) Protocol– A Randomized Controlled Trial on Efficacy and Response Prediction in a Transdiagnostic Psychotherapy Treatment for Anxiety Disorders

Background: This paper describes the study protocol for our clinical trial “Optimizing Outcomes in Psychotherapy for Anxiety Disorders (OPTIMAX)” funded by the Swiss National Science Foundation (10001C_169827). The study aims to establish predictive features for forecasting response to cognitive behavior therapy (CBT) and to investigate mechanisms underlying treatment response. Methods: OPTIMAX comprises a monocentric, randomized-controlled clinical trial. We employ the Unified Treatment Protocol (UP, Barlow, 2017), an established transdiagnostic CBT protocol for treating emotional disorders, to treat patients with anxiety disorders. We use psychological questionnaires, experimental tasks, biological samples, ecological momentary assessments, activity tracking, and smartphone-based passive sensing data in order to derive a multimodal feature set for predictive modeling. We obtain assessments at different time points including baseline, mid-, and post-treatment as well as 6 and 12 months after treatment completion. Anxiety and depression symptom severity are indexed weekly during treatment. We aim to include 150 patients, randomized to CBT versus WAIT group in a 3:1 ratio. Machine learning (e.g., support vector machines, random forest) and linear regression modeling will be employed to establish predictive accuracy in forecasting treatment response. In addition to predictive modelling, we test mechanistic hypotheses, e.g., on the association between self-efficacy, dynamic symptom changes and treatment response, to elucidate mechanisms underlying treatment response. Discussion: The aim of the current trial is to improve current CBT treatment, such as the transdiagnostic unified treatment protocol employed here, by precise forecasting of treatment response and by understanding and, in the future, augmenting underpinning mechanisms and personalizing treatment. Registration: This study has been registered on clinicaltrials.gov (NCT03945617, 10 of May 2019, https://clinicaltrials.gov/ct2/show/NCT03945617)