Optimizing HIV Care Engagement: Usability of a mHealth App for Identifying and Retaining Individuals with Nonviral Suppression in Digital Cohort.

Drive to Zero is a mobile health application (app) designed to identify and retain people with HIV (PWH) who have experienced challenges with achieving or maintaining viral suppression. The app targets PWH who have lacked documented HIV care in the past months and are experiencing medication adherence barriers. Features include an interactive chat for communicating with the study team and access to educational resources to support care engagement and health management.This usability study aimed to assess the Drive to Zero app's ease of use and interface design through expert heuristic evaluation and end-user testing.Usability was evaluated through two approaches: heuristic evaluations conducted by five informatics experts following Nielsen's usability principles, and end-user testing with 20 PWH using the validated Post-Study System Usability Questionnaire and qualitative interviews to collect feedback on app functionality and user experience.Heuristic experts and end-users demonstrated satisfaction with the app's appearance, reporting that it has a simple and intuitive interface for identifying and retaining PWH, which will assist them with study engagement and ultimately reengage with HIV care. However, participants highlighted areas needing improvement, suggesting better accessibility of "home" and "help" buttons to improve user control and a more detailed explanation of the incentive program to enhance user engagement and retention.Usability evaluations provided valuable insights into the Drive to Zero app's design. Areas for improvement were enhancing user controls and improving the readability of the incentive program. These findings will guide iterative refinements, ensuring that future versions of the app improve the usability and acceptability of its target audience.