Cross-cultural adaptation and psychometric testing of the Thai version of the neck disability index in patients with mechanical neck pain

Abstract

The objectives of this study were to produce the Thai version of the Neck Disability Index (Thai NDI) and to evaluate its psychometric properties: reliability, validity, and responsiveness in Thai mechanical neck pain participants. The Thai NDI was translated in accord with the cross-cultural adaptation guidelines. Test-retest reliability was excellent (intraclass correlation coefficient[subscript (2,1)] = 0.90) and the internal consistency was acceptable (Cronbach’s alpha = 0.73). The item-to-total correlation ranged from 0.12 to 0.63. The standard error of measurement was equal to 2.67 corresponding to a minimal detectable change of 7.40. Convergent validity was established by comparing the Thai NDI scores to visual analogue scale for pain (VAS-P) and functional disability (VAS-Fd). Moderate correlations were found for the VAS-P (r = 0.58) and the VAS-Fd (r = 0.53). The Thai NDI showed moderate responsiveness to clinical change (effect size = 0.42, standardized response mean = 0.41). Change in the Thai NDI scores from baseline to the 4-week follow-up were correlated with scores rated on the 15-point box scale for Global Perceived Effect at 0.44. The area under the Receiver Operating Characteristics curve was 0.27. This study successfully translated the Thai NDI with acceptable psychometric properties. However, further study is recommended in order to investigate the feasible of the use of the Thai NDI to assess Thai mechanical neck pain patients