Spanish Version of the System Usability Scale for the Assessment of Electronic Tools: Development and Validation

BACKGROUND: The System Usability Scale (SUS) is a common metric used to assess the usability of a system, and it was initially developed in English. The implementation of electronic systems for clinical counseling (eHealth and mobile health) is increasing worldwide. Therefore, tools are needed to evaluate these applications in the languages and regional contexts in which the electronic tools are developed. OBJECTIVE: This study aims to translate, culturally adapt, and validate the original English version of the SUS into a Spanish version. METHODS: The translation process included forward and backward translation. Forward translations were made by 2 native Spanish speakers who spoke English as their second language, and a backward translation was made by a native English speaker. The Spanish SUS questionnaire was validated by 10 experts in mobile app development. The face validity of the questionnaire was tested with 10 mobile phone users, and the reliability testing was conducted among 88 electronic application users. RESULTS: The content validity index of the new Spanish SUS was good, as indicated by a rating of 0.92 for the relevance of the items. The questionnaire was easy to understand, based on a face validity index of 0.94. The Cronbach α was .812 (95% CI 0.748-0.866; P<.001). CONCLUSIONS: The new Spanish SUS questionnaire is a valid and reliable tool to assess the usability of electronic tools among Spanish-speaking users.