Validation of the Korean version of the oswestry disability index.

STUDY DESIGN: Validation of a translated, culturally adapted questionnaire.

OBJECTIVES: To translate and culturally adapt a Korean version of the Oswestry Disability Index (ODI) and to validate its use in Korean patients.

SUMMARY OF BACKGROUND DATA: The ODI is one of the most widely used and validated instruments for measuring disability in spinal disorders. However, no validated Korean version of the index was available at the time our study was initiated.

METHODS: The study was carried out in three phases: the first was translation into Korean and cultural adaptation of the questionnaire; the second was a pilot study to assess the comprehensibility of the prefinal version and modification; the third was a reliability and validity study of the final version. The Korean version was tested on 206 patients with lumbar spinal disorders who had undergone operations at the authors' institute. Test-retest reliability, internal consistency, concurrent validity, and construct validity were investigated. Follow-up questionnaires were obtained from 39 patients at the 3-month postoperative follow-up meeting. Differences in the ODI, visual analog scale (VAS), and World Health Organization (WHO) quality of life assessment (WHOQOL-BREF) between preoperative and follow-up questionnaires were evaluated. The correlation of the postoperative ODI with the pain rating on a visual analog scale and WHOQOL-BREF was also analyzed.

RESULTS: Test-retest reliability was assessed with 88 patients in a time interval of 48 hours. The intraclass correlation coefficient of test-retest reliability was 0.9167. Reliability estimated by the internal consistency reached a Cronbach's alpha of 0.84. The correlation of the preoperative ODI with the pain rating on a visual analog scale (100 mm) was r = 0.425 (P = 0.0001). The correlation between three of the WHOQOL-BREF domains (physical health, psychological health, and environment) and the ODI was statistically significant. The correlation coefficient between the ODI and physical health domain of the WHOQOL-BREF was r = -0.48 (P < 0.05). The correlations with psychological health and environment domains were low with r = -0.192 and -0.160, respectively, even though statistically significant (P < 0.05). The correlation of the postoperative ODI with the pain rating on a visual analog scale (100 mm) was r = 0.626 (P = 0.0001). The correlation between all four domains of the WHOQOL-BREF and the postoperative ODI was statistically significant.

CONCLUSIONS: The results of this study indicate that the Korean version of the ODI is a reliable and valid instrument for the measurement of disability in Korean patients with lower back problems. The authors recommend this Korean version of the ODI for use in future clinical studies in Korea.