Establishing a usability cut-point for the health information technology usability evaluation scale (Health-ITUES)

Objective: The Health Information Technology Usability Evaluation Scale (Health-ITUES) is a validated and reliable instrument to evaluate usability of information technology (IT) tools. In this study, we aimed to establish the optimal cut-point of the Health-ITUES to identify usability of IT tools. Methods: Adult participants were recruited to a trial evaluating a mobile app for self-managing HIV. Participants completed the Health-ITUES at the 3- and 6-month follow-up. Health-ITUES is a 20-item questionnaire that assesses four subscales: impact, perceived usefulness, perceived ease of use, and user control. The total score ranged from 1 to 5 and a higher score indicates greater usability. App use was defined as the proportion of activities completed by participants in both study arms. The selection of an optimal cut-point involved a series of multiple linear regression models with 500 bootstrap replications to examine the relationship between the Health-ITUES total score and app use, controlling for potential covariates. Results: We included 158 participants; mean age was 49.7 years (SD 10.3), 71% were African American/Black, and 72% were non-Hispanic. Mean Health-ITUES total scores at 3 and 6 months were 4.39 (SD 0.75) and 4.43 (SD 0.75), respectively. App use completed by participants from baseline to the 3-month follow-up visits was 0.61 (SD 0.36, range 0-1.72) and from 3-month to the 6-month follow-up visits was 0.51 (SD 0.37). Participants who reported greater Health-ITUES total score completed more activities [beta = 0.18, 95% Confidence Interval (CI) 0.10-0.27]. The optimal cut-point of 4.32 (95% CI: 4.25-4.56) yielded the lowest p-value to identify usability of IT tools. Conclusions: In this study of adults with HIV, we identified an optimal cut-point of 4.32 on the Health-ITUES total score to define usability. Further studies are needed to validate this cut-point.