The Cultural Adaptation, Reliability, and Validity of Neck Disability Index in Patients With Neck Pain

STUDY DESIGN: The cultural adaptation of Neck Disability Index (NDI), the validity and reliability of Turkish version. OBJECTIVE: The aim of this study was to conduct a study concerning the cultural adaptation of NDI and investigate the validity and reliability of its Turkish version in patients with neck pain. SUMMARY OF BACKGROUND DATA: The NDI is a reliable evaluation instrument for disability but there is no published Turkish version. METHODS: Eighty-eight patients with neck pain for at least 3 months were included in the study. NDI, The Neck Pain and Disability Scale, and Visual Analogue Scale (VAS) were completed by all subjects. Test-retest reliability was determined by using intraclass correlation coefficient and Pearson correlation analysis. For the determination of concurrent validity, the relation between NDI and VAS was examined by Pearson correlation analysis and for the determination of construct validity, the relation between NDI and Neck Pain and Disability Scale was investigated. RESULTS: Intraclass correlation coefficient score for test-retest reliability was 0.979 (95% confidence interval = 0.968-0.986). For concurrent validity, the relation between NDI and VAS was investigated, the r value for test and retest was 0.508 and 0.620, respectively (P < 0.0001). For construct validity, the relation between NDI and the Turkish version of Neck Pain and Disability Scale was investigated, the r value for test and retest was 0.659 (P < 0.0001) and 0.728 (P < 0.0001), respectively. CONCLUSION: The results suggest that the Turkish version of the NDI validated in this study is an easy to understand, reliable, and valid instrument for the measurement of the limitation of activities of daily living and pain caused by neck disorders in the Turkish-speaking population.