Use of modified Northwick Park Neck Pain Questionnaire in patients with postirradiation neck disability: validation study.

BACKGROUND: No available measure exists for postirradiation neck disability. Adoption of the Chinese Northwick Park Neck Pain Questionnaire (NPQ) for patients with postirradiation neck disability was examined in this study. METHODS: Eight physiotherapists and five patients were invited to test the validity of the content. Forty-three patients with neck disability were recruited to evaluate test-retest reliability and internal consistency. The level of neck discomfort, range of neck motion and maximal isometric neck muscle strength, and SF-36 health score were measured for construct validity testing. RESULTS: The questionnaire had good content validity, a high degree of test-retest reliability, internal consistency (intraclass correlation coefficient [ICC], 0.94; Cronbach's alpha, 0.88), and good construct validity. NPQ correlated significantly with most of the subscores of SF-36 (r(s), -0.43 to - 0.71) and numeric rating scale (r(s) = 0.69). CONCLUSION: The modified Chinese NPQ was found to be reliable and valid for the evaluation of postirradiation neck disability.