Background Besides anti-inflammatory medication, physical exercise represents a cornerstone of modern treatment for patients with axial spondyloarthritis (AS). Digital health apps (DHAs) such as the yoga app YogiTherapy could remotely empower patients to autonomously and correctly perform exercises. Objective This study aimed to design and develop a smartphone-based app, YogiTherapy, for patients with AS. To gain additional insights into the usability of the graphical user interface (GUI) for further development of the app, this study focused exclusively on evaluating users’ interaction with the GUI. Methods The development of the app and the user experience study took place between October 2020 and March 2021. The DHA was designed by engineering students, rheumatologists, and patients with AS. After the initial development process, a pilot version of the app was evaluated by 5 patients and 5 rheumatologists. The participants had to interact with the app’s GUI and complete 5 navigation tasks within the app. Subsequently, the completion rate and experience questionnaire (attractiveness, perspicuity, efficiency, dependability, stimulation, and novelty) were completed by the patients. Results The results of the posttest questionnaires showed that most patients were already familiar with digital apps (4/5, 80%). The task completion rates of the usability test were 100% (5/5) for the tasks T1 and T2, which included selecting and starting a yoga lesson and navigating to an information page. Rheumatologists indicated that they were even more experienced with digital devices (2/5, 40% experts; 3/5, 60% intermediates). In this case, they scored task completion rates of 100% (5/5) for all 5 usability tasks T1 to T5. The mean results from the User Experience Questionnaire range from −3 (most negative) to +3 (most positive). According to rheumatologists’ evaluations, attractiveness (mean 2.267, SD 0.401) and stimulation (mean 2.250, SD 0.354) achieved the best mean results compared with dependability (mean 2.000, SD 0.395). Patients rated attractiveness at a mean of 2.167 (SD 0.565) and stimulation at a mean of 1.950 (SD 0.873). The lowest mean score was reported for perspicuity (mean 1.250, SD 1.425). Conclusions The newly developed and tested DHA YogiTherapy demonstrated moderate usability among rheumatologists and patients with rheumatic diseases. The app can be used by patients with AS as a complementary treatment. The initial evaluation of the GUI identified significant usability problems that need to be addressed before the start of a clinical evaluation. Prospective trials are also needed in the second step to prove the clinical benefits of the app.

BACKGROUND Besides anti-inflammatory medication, physical exercise represents a cornerstone of modern treatment for patients with Axial Spondylarthritis (AS). Digital health applications (DHA) like the Yoga App "YogiTherapy" could empower patients to autonomously and correctly perform exercises remotely. OBJECTIVE This study aimed to develop, design, and test the usability of the smartphone-based app YogiTherapy for patients with Axial Spondylarthritis. METHODS The development of the app and the user experience study took place between October 2020 and March 2021. The DHA was designed by students, rheumatologists, and AS patients. After the initial development process, a pilot version of the app was evaluated prospectively by 5 patients and 5 rheumatologists. Participants had to complete different predefined tasks using the app. Then the competition rate and the experience questionnaire (Attractiveness, Perspicuity, Efficiency, Dependability, Stimulation, and Novelty) were finalized by patients. RESULTS The results of the post-test questionnaires showed that the majority of the patient group was already familiar with digital applications (80 % of the patients). The task completion rate of the usability test was 100 % in tasks i and ii, which included selecting and starting a yoga lesson and navigating to an information page. Rheumatologists felt even more experienced in digital devices (40 % experts, 60 % intermediates). In this case, the task completion rate of the usability test was 100 % (5 /5). In the user experience questionnaire completed by rheumatologists, attractiveness (2.267 SD 0.401) and stimulation (2.250 SD 0.354) achieved the best results compared to dependability (2.00 SD 0.395). Patients reported attractiveness with 2.167 SD 0.565 and stimulation with 1.950 SD 0.873. The lowest mean score was scaled for perspicuity (1.250 SD 1.425). CONCLUSIONS The newly developed and tested DHA YogiTherapy demonstrated high usability among rheumatologists and AS patients, suggesting simple implementation into clinical routine care. The app might potentially be used by patients with AS as a complementary treatment. Prospective trials are needed to prove the benefit of the app.