Translation, Validation, and Crosscultural Adaptation of the Hebrew Version of the Neck Disability Index.

STUDY DESIGN The present study's design was translation and crosscultural validation of the Neck Disability Index (NDI). OBJECTIVE The aim of the study was to translate and culturally adapt the NDI into Hebrew language and to evaluate the psychometric properties of this version. SUMMARY OF BACKGROUND DATA As yet, no Hebrew language neck pain and disability questionnaires exist. The NDI is widely used and validated among different patient populations with neck pain. METHODS The English version of the NDI was translated into Hebrew according to the published guidelines. A total of 100 patients with neck pain participated in the study. Inclusion criteria were age 18 years and older, neck pain, and ability to read and speak Hebrew. Exclusion criteria were cancer or suspected tumor, neck pain related to vertebral fracture, or neurological disease. Participants were asked to complete the NDI-Hebrew version (NDI-H), Numeric Pain Rating Scale (NPRS), and Patient-Specific Functional Scale (PSFS). Seventy-three patients completed the NDI-H twice in an interval of 2 days. Psychometric properties included test-retest reliability (intraclass correlation coefficient), internal consistency (Cronbach α), convergent validity (Pearson correlation), and factor analysis. RESULTS The NDI-H demonstrated excellent test-retest reliability (intraclass correlation coefficient ranged from 0.827 to 0.929; Pv < 0.001). Cronbach α value was excellent (0.855). A very good correlation was found between the NDI-H and NPRS scores (r = 0.611, P < 0.001) and a good correlation between the NDI-H and PSFS score (r = 0.417, P < 0.001). Factor analysis revealed a two-factor solution representing daily function and pain and symptoms. CONCLUSION The NDI-H is a valid and reliable instrument to measure functional limitations and disability in Hebrew-speaking patients with neck pain. LEVEL OF EVIDENCE NA.