Cross-cultural adaptation and validation of a Spanish version of the self-administered foot evaluation questionnaire (SAFE-Q)

Abstract

Background: The self-administered foot evaluation questionnaire is a comprehensive measure for assessing the perception of patients regarding their foot-related problems. However, it is currently only available in English and Japanesse. Therefore, this study aimed to cross-culturally adapt the questionnaire to Spanish and assess its psychometric properties. Methods: The methodology recommended by the International Society for Pharmaco Economics and Outcomes Research for translating and validating patient-reported outcome measures was followed for the Spanish translation. After a pilot study with 10 patients and 10 controls, an observational study was carried out between March and December 2021. The Spanish version of the questionnaire was filled by 100 patients with unilateral foot disorders, and the time spent to complete each questionnaire was recorded. Cronbach's alpha was calculated to analyze the internal consistency of the scale and Pearson's correlation coefficients for the degree of inter-subscale associations. Results: The maximum correlation coefficient for the Physical Functioning, Daily Living, and Social Functioning subscales was 0.768. The inter-subscale correlation coefficients were significant (p < 0.001). Additionally, the value of Cronbach's alpha for the whole scale was 0.894 (95% confidence interval, 0.858–0.924). The values of Cronbach's alpha varied between 0.863 and 0.889 when the value of one of the five subscales was suppressed, which can be considered a measure of good internal consistency. Conclusion: The Spanish version of the questionnaire is valid and reliable. The method followed for its transcultural adaptation ensured its conceptual equivalence with the original questionnaire. Health practitioners can use the self-administered foot evaluation questionnaire as a complementary method to assess the interventions performed for ankle and foot disorders among native Spanish speakers; however, further research is necessary to assess its consistency for use by populations from other Spanish-speaking countries.