  Background In the recent decades, the number of apps promoting health
behaviors and health-related strategies and interventions has increased
alongside the number of smartphone users. Nevertheless, the validity process
for measuring and reporting app quality remains unsatisfactory for health
professionals and end users and represents a public health concern. The Mobile
Application Rating Scale (MARS) is a tool validated and widely used in the
scientific literature to evaluate and compare mHealth app functionalities.
However, MARS is not adapted to the French culture nor to the language.
Objective This study aims to translate, adapt, and validate the equivalent
French version of MARS (ie, MARS-F). Methods The original MARS was first
translated to French by two independent bilingual scientists, and their common
version was blind back-translated twice by two native English speakers,
culminating in a final well-established MARS-F. Its comprehensibility was then
evaluated by 6 individuals (3 researchers and 3 nonacademics), and the final
MARS-F version was created. Two bilingual raters independently completed the
evaluation of 63 apps using MARS and MARS-F. Interrater reliability was
assessed using intraclass correlation coefficients. In addition, internal
consistency and validity of both scales were assessed. Mokken scale analysis
was used to investigate the scalability of both MARS and MARS-F. Results MARS-F
had a good alignment with the original MARS, with properties comparable between
the two scales. The correlation coefficients (r) between the corresponding
dimensions of MARS and MARS-F ranged from 0.97 to 0.99. The internal
consistencies of the MARS-F dimensions engagement ($\omega$=0.79),
functionality ($\omega$=0.79), esthetics ($\omega$=0.78), and information
quality ($\omega$=0.61) were acceptable and that for the overall MARS score
($\omega$=0.86) was good. Mokken scale analysis revealed a strong scalability
for MARS (Loevinger H=0.37) and a good scalability for MARS-F (H=0.35).
Conclusions MARS-F is a valid tool, and it would serve as a crucial aid for
researchers, health care professionals, public health authorities, and
interested third parties, to assess the quality of mHealth apps in
French-speaking countries.
