Maximising the efficacy of in vivo exposure therapy using smartphone-assisted just-in-time adaptive intervention for anxiety disorders: study protocol for a randomised controlled trial.

INTRODUCTION: For anxiety disorders (ADs), the preferred treatment is cognitive-behavioural therapy (CBT), with in vivo exposure (IVE) as its main component. IVE aims to gradually expose the patient to feared stimuli and situations to encourage habituation. Despite its effectiveness, it is a hard component for patients, especially when applied on their own. Therefore, a (co-)therapist usually supports the exposure requiring considerable time and resources. Meanwhile, smartphones have become a promising tool to complement and deliver psychological treatments. METHODS AND ANALYSIS: The study presents the protocol of a randomised controlled trial to evaluate the efficacy of an app (SyMptOMS-ET) to support IVE for ADs. The app provides a just-in-time momentary ecological intervention by profiting from advanced smartphone features to monitor, interact and guide the patient through the exposure based on their condition and context. Participants (158) will be adult volunteers suffering from Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) ADs (specific phobia, agoraphobia, panic disorder and social anxiety). They will be randomly allocated to (1) CBT with traditional IVE (79) and (2) CBT with IVE using SyMptOMS-ET (79). The Diagnostic Interview for DSM, Fourth Edition, Text Revision (DSM-IV-TR) ADs will be used as a diagnostic measure. Primary outcome measures will be assessed with interference and fear scales from the Anxiety Disorders Interview Schedule for DSM-IV and with target behaviours; acceptability, satisfaction, usability and app quality will also be measured. Patients will be assessed at baseline, after treatment and at 1-month, 6-month and 12-month follow-ups. Data will be analysed both per-protocol and by intention-to-treat. It will contribute to the knowledge of just-in-time interventions, making the exposure component more accessible to patients. ETHICS AND DISSEMINATION: The Universitat Jaume I Ethics Committee (Castellón, Spain) granted approval for the study (CEISH/51/2024). The results from this study will be actively disseminated through manuscript publications and presentations at national and international conferences. TRIAL REGISTRATION NUMBER: NCT06788119.