The Impact of Intervention Design on User Engagement in Digital Therapeutics Research: Factorial Experiment With a Mixed Methods Study (Preprint)

Abstract

BACKGROUND User engagement is crucial for Digital Therapeutics (DTx) effectiveness; due to variations in the conceptualization of engagement and intervention design, assessment and retention of engagement remains challenging. OBJECTIVE The study investigated the influence of the perceived acceptability of experimental intervention components and satisfaction with core intervention components in DTx on user engagement, while also identifying potential barriers and facilitators to user engagement. METHODS This was a mixed-method study with a 2x2 factorial design, involving 12 Atopic Dermatitis outpatients. Participants were randomized into four experimental groups based on push notification (basic/advanced) and human coach (on/off) experimental intervention components. All participants engaged in self-monitoring and learning courses as core intervention components within an app-based intervention over eight weeks. Data were collected through in-app behavioral data, physicians/self-reported questionnaires, and semi-structured interviews assessed at baseline, four weeks, and eight weeks. Descriptive statistics and thematic analysis were used to evaluate user engagement, perceived acceptability of experimental intervention components (i.e., push notification and human coach), satisfaction with core intervention components (i.e., self-monitoring and learning course), and intervention effectiveness through clinical outcomes. RESULTS The primary outcome indicated that Group 4, provided with Advanced level push notifications and a Human coach, showed higher completion rates for self-monitoring forms and learning courses compared to the predetermined threshold of clinical significance. Qualitative data analysis revealed three key themes: (1) perceived acceptability of the experimental intervention components, (2) satisfaction with the core intervention components, and (3) suggestions for improvement in the overall intervention program. Regarding clinical outcomes, the Perceived Stress Scale and Dermatology Life Quality Index scores presented the highest improvement in Group 4. CONCLUSIONS These findings will help refine the intervention and inform the design of a subsequent randomized trial to test its effectiveness. Furthermore, this design may serve as a model for broadly examining and optimizing overall engagement in DTx and for future investigation into the complex relationship between engagement and clinical outcomes. CLINICALTRIAL Clinical Research Information Service KCT0007675; https://cris.nih.go.kr/cris/search/detailSearch.do?seq=22592&search_page=L