Validity and reliability of the Greek version of the Quebec Back Pain Disability Scale.

OBJECTIVES Low back pain is related to functional status and possible resulting disability. The Quebec Back Pain Disability Scale (QBPDS) has been used widely to evaluate functional disability in patients with low back pain. The purpose of this study was to assess: (a) the face and content validity, (b) the factor structure, (c) the concurrent validity, (d) the discriminant validity, (e) the internal consistency and the test-retest reliability (ICC) of the Greek version of the QBPDS. METHODS One hundred and sixty patients with low back pain participated in the study. Face and content validity of the translated QBPDS were first investigated and afterwards exploratory factor analysis (EFA) was chosen to examine the factor structure of it. The concurrent and discriminant validity of the QBPDS was also assessed by a number of valid constructs. Finally, Cronbach α and Pearson r (ICC) were used to investigate the reliability of the instrument. RESULTS The face and content validity of the QBPDS were supported and the EFA confirmed the sixth initial factor structure of the instrument. The concurrent and discriminant validity of it was confirmed by examining correlations between the QBPDS with other constructs. The Cronbach a and the ICCs indices of the instrument were acceptable. CONCLUSION The Greek translation of the QBPDS provided reliable and valid instrument for the evaluation of Greek patients with low back pain.