Messages and Notifications for the "OA Coach" Knee Osteoarthritis Self-Management Mobile App: Codevelopment and Evaluation Using a Participatory Research Design With Focus Groups and Surveys.

Background: The OA Coach mobile app is a digital self-management tool designed to support people with knee osteoarthritis (OA). Objective: We aimed to enhance the digital user experience of the OA Coach app by working with consumers, health professionals, and researchers to (1) improve existing OA Coach app call-to-action and encouragement notifications by applying behavior change theory, refining, reviewing, and adapting them, and (2) co-design new educational messages based on international OA guidelines. Methods: This mixed methods study used a 3-phase process for improving existing notifications and developing new educational messages: (1) initial development and/or enhancement using behavior change techniques and accessible language, (2) expert review, and (3) refinement based on participant feedback. We enhanced the existing notifications to incorporate behavior change theory and improve readability, then we assessed ease of understanding, usefulness, and motivational impact in an online survey using 1-5 Likert scales and free-text responses. Median scores and IQRs were calculated, free-text responses were summarized using content analysis, and notifications that scored ≤12/15 and/or had 2 or more consistent recommendations in free-text responses were systematically refined. The new weekly educational messages were initially drafted based on OA clinical practice guidelines, then reviewed in 3 focus groups (in person and online) for detailed guidance on topic selection, language, and timing. Content analysis of focus group data informed systematic refinement of the messages. The refined messages were assessed for understanding and usefulness in an online survey (1-5 Likert scales), and free-text responses were refined further based on survey results. Results: Fifty-seven participants assessed the existing notifications in the survey. Consumers rated notifications relating to sleep and mood the lowest, and those encouraging logging pain scores the highest. Health professionals and researchers reported a median score of 12/15 across all notifications, with greatest variability observed for step count, activity tracker use, and pain score logging. Eighty notifications were refined to enhance clarity, engagement, and effectiveness in prompting meaningful actions by future OA Coach users. Overall, 6 consumers, 7 health professionals, and 6 researchers participated in 3 focus groups to co-design 14 educational messages. A preference for a consistent message structure emerged: a descriptive heading, a brief introductory sentence, followed by 3 or 4 key points with practical examples, and concluded with a motivating statement. Key themes guiding modifications for both notifications and educational messages included reducing technical jargon, simplifying colloquial expressions, and removing language perceived to be patronizing or frustrating. Conclusions: Through an iterative process, we used behavior change theory and worked with consumers, health professionals, and researchers to identify key preferences for message content, language, tone, and structure. These insights informed the refinement of 80 notifications and the co-design of 14 educational messages for the OA Coach app.