Development of a Brazilian Portuguese version of the Oswestry Disability Index: cross-cultural adaptation, reliability, and validity.

STUDY DESIGN Translation, revision, back-translation, and 3-way validity were performed. OBJECTIVE The objective of this study was to translate a version of the Oswestry Disability Index (ODI) into Brazilian Portuguese and evaluate its reliability. SUMMARY OF BACKGROUND DATA Reports in the literature have identified a need for internationally standardized and reliable measurements to analyze back pain. The ODI has become one of the principal outcome measurements used in the management of spinal disorders. METHODS The cross-cultural adaptation was performed according to the internationally recommended methodology, using the following guidelines: translation, back-translation; revision by a committee, and pretesting. The psychometric properties were evaluated by administering the questionnaire to 120 subjects with back pain. Reliability was estimated through stability and homogeneity assessment. The validity was tested comparing ODI scores with the following measurements: Roland-Morris Disability Questionnaire, SF-36, and a Numerical Pain Scale. RESULTS Good internal consistency was found (Cronbach's alpha = 0.87). Intraclass correlation coefficient for test-retest reliability was 0.99. The ODI showed moderate correlation with pain measurement (r = 0.66). Relatively high correlation was also found between the ODI and the Roland-Morris scores (r = 0.81). There was significant correlation (P < 0.001) between ODI scores and the 8 scales of the SF-36. CONCLUSIONS The data showed that the cultural adaptation process was successful and that the adapted instrument demonstrated having excellent psychometric properties, reliable in the Brazilian culture.