NutriA-Senior, a Mobile App to Enhance Nutritional Awareness in Older Adults: Design and Pilot Usability Study

Background: Mobile health is emerging as a ubiquitous paradigm for delivering health care interventions when self-management is feasible. However, interventions targeting older or frail participants should account for age-related cognitive, visual, and physical needs to optimize usability and long-term retention. Objective: This paper describes the rationale, design, and implementation of Nutritional App-Senior (NutriA-S), a theory-informed mobile app developed to enhance nutritional education in older adults with sarcopenia or probable sarcopenia. Moreover, we present the results of a usability study conducted in a cohort of age-matched healthy volunteers. Methods: NutriA-S was designed as a self-instructional app built on the Moodle e-learning platform. It includes 24 progression modules containing interactive quizzes and associated informational items aimed at engaging users by sustaining attention and improving nutritional knowledge. A 4-week pilot usability study was conducted with 35 healthy volunteers aged 65 to 85 years, recruited through flyers posted in 2 outpatient settings. After recruitment, participants used the app remotely at home with telemedicine-based monitoring and support. At the end of the study, usability was quantitatively assessed using the Italian version of the standard System Usability Scale (SUS) and the User Version of the Mobile Application Rating Scale (uMARS). Results: The SUS questionnaire yielded a median total score of 80 out of 100 (IQR 55.00-92.50), indicating good perceived usability, with more than half of the participants rating the app as acceptable (above the threshold of 68). The overall median uMARS score was 4.083 (IQR 3.68-4.30), with the functionality and information domains achieving the highest median scores of 4.5 (with IQRs of 4.00-4.50 and 4.13-4.75, respectively), confirming that older adults perceived the tool as technically reliable and highly credible. Conclusions: This pilot usability study shows encouraging results, suggesting that NutriA-S is a highly usable, intuitive, and credible digital health tool for older adults. The identified limitations in items like customizability, willingness to pay, and willingness to use the app frequently, which received lower scores, will guide app refinements before deploying NutriA-S in an upcoming randomized controlled trial for older adults with sarcopenia or probable sarcopenia.