Development of the Italian version of the Oswestry Disability Index, ODI-I. A cross-cultural adaptation, reliability and validity study

Study Design. Evaluation of the psychometric properties of a translated, culturally adapted questionnaire. Objective. Translating, cul¬turally adapting, and validating the Italian version of the Oswestry Disability Index (ODI-I), allowing its use in Italian-speaking low back pain patients inside and outside Italy. Summary of Background Data. Growing attention is devoted to standardized outcome measures to improve interventions for low back pain. A translated form of the ODI in patients with low back pain has never been validated within the Italian population. Methods. The ODI-I questionnaire was developed involving forward-backward translation, final review by an expert committee and test of the pre-final version to establish as better as possible proper correspondence with the original English latest version (2.1a). Psychometric testing included factor analysis, reliability by internal consistency (Cronbach’s alpha) and test-retest repeatability (Intraclass Coefficient Correlation), concurrent validity by comparing the ODI-I to Visual Analogue Scale, VAS (Pearson’s correlation), and construct validity by comparing the ODI-I to Roland Morris Disability Questionnaire, RMDQ, and to Short Form Health Survey, SF-36 (Pearson’s correlation). Results. The Authors required a three-month period before achieving a shared version of the ODI-I. The questionnaire was administered to 126 subjects, showing good acceptability. Factor analysis demonstrated a one-factor structure (45% of explained variance). The questionnaire showed high internal consistency (Cronbach’s alpha 0.855) and good test-retest reliability (ICC=0.961). Concurrent Validity was confirmed by a high correlation with VAS (r = 0.73, p<0.001), Construct Validity revealed high correlations with RMDQ (r = 0.819, p