Development and validation of the Japanese version of the uMARS (user version of the mobile app rating system)

Although the global market of Mobile Health Apps (mHealth apps) continues to grow dramatically, most mHealth apps still not only lack evidence base but have even not been evaluated for the basic usability or functionality. The User Version of the Mobile App Rating Scale (uMARS) was developed to allow end users to assess mHealth apps objectively and subjectively. However, there is no Japanese version of uMARS to date.

The purpose of this study is (1) to develop a validated Japanese version of uMARS and (2) to assess the translated version's reliability and validity in evaluating mHealth apps.

The original uMARS was adapted for Japanese use by four specialists using universalist cross-cultural methods. Translation/back-translation was reviewed by the author of the original version of uMARS, and confirmed. Its reliability and validity were further evaluated as part of a prospective cohort study of postoperative patients using a new mHealth app.

Conceptual equivalence was analyzed and all items in all subcategories of the original uMARS were included in the Japanese version. Internal consistency was deemed acceptable for all subscales of objective and subjective quality with a Cronbach's alpha of 0.75-0.85. Test-retest reliability of all subscales was also acceptable with intraclass correlation coefficients (ICCs) of 0.57-0.88. Convergent/divergent validity and concurrent validity were also considered acceptable.

A Japanese version of uMARS was cross-culturally validated and found to be as reliable as the original uMARS. This Japanese version of uMARS is expected to become a standard tool in assessing the quality of mHealth apps in Japan.