The Mexican Version of the Interactive mHealth App Usability Questionnaire (Mx-MAUQ) in Women With Breast Cancer: Instrument Validation Study.

Background: Successful eHealth applications require careful assessment to ensure their ease of use, usefulness, and user satisfaction. Responsive web applications are eHealth tools that operate on any internet-enabled device across all browsers. Psychometrically valid assessment tools are essential for effectively evaluating these applications, yet no validated eHealth questionnaire exists for assessing their usability and user satisfaction in Mexico. Objective: The objective of this study is to adapt the mHealth App Usability Questionnaire (MAUQ) for responsive web application assessment in Mexico and validate adapted Mx-MAUQ content, construct validity, internal consistency, and its ability to distinguish between patient subgroups. Methods: We conducted a psychometric validation study of Mx-MAUQ with women aged 20 to 75 diagnosed with stage I-III breast cancer who had begun neoadjuvant or adjuvant treatment within the last six weeks and used the responsive "OncoMama App" for 1 month. The study excluded women with stage IV breast cancer, illiterate women, and those with blindness, cognitive disability, or severe depression. Participants were recruited from oncology services at 4 hospitals belonging to the Mexican Institute of Social Security between August 2023 and November 2024. The study involved translating and adapting the MAUQ while evaluating its content through expert panels and cognitive interviews with women. The Mx-MAUQ construct was assessed through exploratory factor analysis (EFA), internal consistency via Cronbach α, and Mx-MAUQ's capacity to distinguish between subgroups of patients with breast cancer using the Wilcoxon rank sum test. Results: A total of 210 women participated, with 75.2% (n=158) aged 60 or younger and 64.3% (n=135) having high school education. The expert panel granted all Mx-MAUQ items a content validity index (CVI) above 0.7. Experts have found that the MAUQ questions are general enough to be relevant not only to mobile apps or specific medical conditions but also to a variety of digital platforms, including responsive web applications and different health conditions. The cognitive interviews revealed 3 unclear terms in the questionnaire; consequently, we defined "application interface" and changed "social settings" to "social environments" and "manage my health" to "take care of my health." EFA identified 2 factors explaining 91.6% of the variance and retaining all items. The first factor, "Ease of Use," consists of 9 items and has a Cronbach α of .94. The second factor, "Satisfaction, Usefulness, and System Information Arrangement," includes 12 items and has a Cronbach α of .97. Women with higher education levels scored significantly higher for both factors, as well as the overall Mx-MAUQ score, than those with lower educational attainment. Conclusions: Mx-MAUQ showed satisfactory psychometric properties based on EFA, internal consistency, and discriminant analysis, making it a suitable tool for a comprehensive assessment of the usability of interactive web-based eHealth applications for women with breast cancer in Mexico.