Documenting user-centered design in mHealth for older adults with low digital literacy: Towards an operational blueprint and reporting checklist documenting UCD in mHealth for older adults.

BACKGROUND: Transparent reporting of user-centered design (UCD) in mobile health (mHealth) interventions remains limited and poorly standardized, hindering replicability and equity. Existing frameworks, such as ISO 9241-210, FRAME, and TIDieR, provide partial guidance but do not capture completely the UCD cycle. OBJECTIVE: To propose an operational blueprint and a practical checklist for reporting UCD in mHealth interventions, and to conduct a pilot content validation of the checklist with application to older adults in Brazil. METHODS: Elements from ISO 9241-210, FRAME, and TIDieR were integrated into the iterative development of an mHealth app ("Viva"). Twenty older adults (mean age 65.0 (3.5) years; 70% high school, 15% elementary, 15% bachelor's degree) participated in focus groups, usability testing, and iterative prototyping. Usability was assessed with the System Usability Scale (SUS) and the Suitability Assessment of Materials (SAM). Adaptations were documented with FRAME. RESULTS: After two prototyping cycles, mean SUS scores increased from 71.2 (SD 4.7) to 87.1 (SD 5.9), representing a statistically significant improvement of +15.9 points (95%CI: +12.1 to +19.6; p<0.001; d=1.10). SAM scores improved from 34.9% (SD 5.7) to 70.7% (SD 13.0), an increase of +35.8 percentage points (95%CI: +27.4 to +44.2; p<0.001; d=0.90). Attrition was zero, with all participants completing testing. FRAME analysis documented 18 adaptations, mainly related to navigation, terminology, and layout. The final reporting checklist included 13 items organized into eight domains: context, stakeholder involvement, design process, adaptations, outcomes, integration, equity & inclusion, and transparency. CONCLUSIONS: The proposed blueprint and checklist address critical gaps in UCD reporting by making design processes auditable and replicable. Although further multicenter validation is required, these tools provide a preliminary step toward harmonized reporting practices, with potential to improve transparency, equity, and clinical relevance in digital health, pending broader external validation.