Validation of the Korean Version of the Neck Pain and Disability Scale

STUDY DESIGN: A prospective study. PURPOSE: To evaluate the reliability and validity of the adapted Korean version of the Neck Pain and Disability Scale (NPDS). OVERVIEW OF LITERATURE: The validity of Korean version of NPDS has not been completely demonstrated yet. METHODS: Translation/retranslation of the English version of NPDS was conducted, and all steps of the cross-cultural adaptation process were performed. The Korean version of the visual analog scale (VAS) measure of pain, NPDS and the previously validated Short Form-36 (SF-36) were mailed to 91 patients, who had been surgically treated for degenerative cervical disease. Eighty-one patients responded to the first mailing of questionnaires and 69 of the first time responder returned their second survey. Factor analysis and reliability assessment by kappa statistics of agreement for each item, the intraclass correlation coefficient and Cronbach's α were conducted. Concurrent and construct validity were also evaluated by comparing the responses of NPDS with the results of VAS and responses of SF-36. RESULTS: Factor analysis extracted 3 factors. All items had a kappa statistics of agreement greater than 0.6. The NPDS showed excellent test/re-test reliability. Internal consistency of Cronbach's α was found to be very good. The NPDS was correlated with the VAS. The Korean version of NPDS showed good significant correlation with SF-36 total score and with single SF-36 domains scores. CONCLUSIONS: The adapted Korean version of the NPDS was successfully translated and is considered suitable for outcome assessments in the Korean-speaking patients with neck pain.