Background: Panic disorder is one of the most prevalent anxiety disorders. Contemporary research has proven effectiveness of internet-based self-help interventions for panic disorder. However, these approaches are limited with respect to motivate and support clients in exposure and monitoring tasks which are both fundamental components of CBT-based therapy. We argue, that the time- and location-independent nature of smartphones makes them in particular suitable to overcome these limitations.

Objective: The goal of this study is to evaluate the feasibility and acceptance of a newly developed mobile application for panic disorder and to report preliminary within-group effects.

Methods: We developed the mobile application "GET.ON PAPP" that guides and engages clients in performing self-exposures and self-monitoring. As extensive reading and writing parts are difficult to handle on smartphones, the application is complemented by a training that is delivered over the internet. Both, mobile application and online-training are based on cognitive behavioral principles for the treatment of panic disorder. For the development, an iterative design approach has been employed that involved researchers from different disciplines as well as therapists and potential end-users. We will conduct a feasibility study with ten participants with clinical and subclinical panic disorder with and without agoraphobia. Participants will be recruited from the general population of Germany. To increase ecological validity, participants will run the mobile application on their own smartphones. At the completion of the study, participants will be interviewed to report on their experiences with the mobile application as well as on technical difficulties. Participants will also be asked to complete a brief questionnaire on acceptance as well as the Panic and Agoraphobia Scale. After integrating changes resulting from the feasibility study, an RCT will be conducted.