Study Design. This study's design was a cross-cultural validation of the Neck Disability Index (NDI) and Neck Pain and Disability Scale (NPDS).
Objective. To translate and validate Chinese versions of the NDI and the NPDS.
Summary of Background Data. The widely used NDI and NPDS scales have not been translated and validated for Chinese-speaking patients with neck pain.
Methods. The translation and cultural adaptation of the original questionnaires were carried out in accordance with the published guidelines. A total of 125 patients with neck pain participated in the study. Patients were asked to complete a questionnaire booklet including the NDI, the NPDS, the SF-36, and a visual analog scale (VAS) of pain. To determine the test-retest reliability, 45 patients were asked to complete the questionnaire booklet a second time within 48 hours of the first completion.
Results. The Cronbach α coefficient for the NDI was 0.89, and those for the 3 subscales of the NPDS were found to be satisfactory (0.91, 0.88, and 0.82, respectively). The NDI and the NPDS subscales showed excellent test-retest reliability (the intraclass correlation coefficient ranged from 0.86 to 0.95; P < 0.01). The correlation between the NDI and the NPDS subscales and functional scales of the SF-36 showed desirable results, indicating a good convergent validity (Pearson correlation coefficients ranged from −0.19 to −0.76). The correlation between the NDI and the VAS was 0.75, and that between the NPDS subscales and the VAS ranged from 0.62 to 0.76 (P < 0.01).
Conclusion. The Chinese versions of the NDI and the NPDS are reliable and valid instruments to measure functional status in Chinese-speaking patients with neck pain in China. They are simple and easy to use, and can now be applied in clinical settings and future outcome studies in China and other Chinese-speaking communities.