Spanish Version of the mHealth App Usability Questionnaire (S-MAUQ): Translation, Adaptation, and Validation Study.

Background: In the current digital landscape, ensuring optimal usability is one of the most crucial factors determining the success of any mobile app. Questionnaire-based usability evaluations represent a highly prevalent methodology for this purpose. To date, questionnaires have been developed to assess the general system usability; however, there are hardly any questionnaires specifically designed to assess the usability of mobile health (mHealth) apps. The most widespread, the mHealth App Usability Questionnaire (MAUQ), has been developed in 4 versions according to the type of app (interactive or standalone) and the target user (patient or provider). Objective: The objective of this study was to translate and validate the English version of the MAUQ (standalone, for patients) into a Spanish version (S-MAUQ). Methods: The methodology used here follows that proposed by Sousa and Rojjanasrirat, which comprises 4 stages. The initial stage of the process entails a translation, harmonization, and adaptation procedure. The second and third entailed content validation (by 10 experts) and face validation (by 12 target users), respectively, which were conducted to evaluate the relevance and clarity of the questionnaire items. The item-level content validity index, scale content validity index (S-CVI), item-level face validity index, and scale face validity index (S-FVI), as well as the modified kappa statistic (κ) were used to evaluate interrater agreement among the raters, considering the probability of agreement by chance (Pc). The fourth and final stage of the process involved the assessment of the questionnaire's reliability. A sample of 61 young adult participants installed an mHealth app (the Yazio app), used it, and responded to the S-MAUQ. The Cronbach α value for the entire questionnaire and its subscales were then calculated. Results: For the second stage, the S-CVI was initially 0.778. We removed items #14 and #15 from the Spanish version as they were unclear and not relevant. The S-CVI changed to 0.881. The third stage had an S-FVI of 0.927, indicating that the items are clear and straightforward for the nonexpert target user to understand. Furthermore, with each κ value >0.74, the validity of the instrument is supported. The fourth stage demonstrated the reliability of the S-MAUQ with a Cronbach α value of 0.87. Conclusions: The final version of the S-MAUQ met the validation criteria, demonstrating reliability and validity that are comparable with those of the original version. Consequently, the S-MAUQ is suitable for evaluating the usability of mHealth apps for young Spanish adults. Further research involving larger and more diverse samples is recommended.