Engagement with Incharge App - a Mobile Health Intervention to Improve Adherence to Hydroxyurea Among Individuals with Sickle Cell Disease

Introduction: Sickle cell disease (SCD) affects around 100,000 people in the United States, causing acute vaso-occlusive events and chronic end-organ damage. Hydroxyurea (HU) is a proven treatment for SCD that reduces acute and chronic complications. Despite extensive evidence and guideline recommendations, many people with SCD do not receive optimal HU therapy. Our group has shown that using the InCharge Health app, a SCD-specific app co-developed with patients (Alberts et al, JMIR mHealth uHealth, 2020), for at least 24 weeks, increases adherence to HU up to 29%, but engagement with the app varied among users. This study reports user's perceptions of the app relative to their degree of app utilization, thus informing future app adaptations to optimize app engagement and potentiate its effect. Methods: The InCharge Health app features included daily reminders, adherence and pain progress tracking, communication with providers and other patients, hospital mode deactivation, educational resources, and an accountability partner. Participants used the InCharge Health app and completed the validated Mobile Application Rating Scale (MARS, Stoyanov SR, JMIR mHealth uHealth, 2015) after 24 weeks of app use. The MARS evaluates the quality of mobile health apps by eliciting users' perceptions of engagement, functionality, aesthetics, and information quality. App utilization data (% of the study days) were obtained from the backend of the app and defined as low (75%). HU percentage of days covered (PDC), the percentage of days covered by filled HU prescriptions during the study period, was used as a proxy for medication adherence. Baseline pain frequency 12 months before study enrollment was obtained using the Adult Sickle Cell Quality of Life Measurement Information System. After 24 weeks, the ease of use, importance, and helpfulness of app features were evaluated and stratified based on the level of app usage. Results: A total of 208 participants enrolled, median age 26.3 years (range, 15 to 45), 52% (108/208) females, 87% (181/208) with HbSS/Sβ 0-thalassemia. Fifty-eight percent (121/208) of participants were low app utilizers, 19.2% (40/208) medium low, 15.9% (33/208) medium high, and 6.7% (14/208) high app utilizers (Table 1). As app usage increased, users reported lower pain frequency and pain severity. After 24 weeks, all groups increased PDC, which sustained post-study, and the magnitude of an incr