title: A systematic review of cross-cultural adaptation of the neck disability index.
abstract: METHODS
  Systematic review of cross-cultural adaptation.
  
  
  OBJECTIVE
  To perform a systematic review of cross-cultural adaptations of the Neck Disability Index (NDI) and to give a critical assessment to improve its translation.
  
  
  BACKGROUND
  The NDI is used to assess functional capacity and physical activity in patients with neck pain, but the quality of its cross-cultural adaptations has not been systematically reviewed.
  
  
  METHODS
  PubMed, Cochrane Library, and EMBASE were searched up through 2013 to identify studies of cross-cultural NDI adaptations. Search terms were "Neck Disability Index" or "NDI" and "cross-cultur*" or "cultur*" or "valid*" or "equivalence" or "transl*." Data were extracted and study quality was assessed.
  
  
  RESULTS
  Twenty-four different NDI versions were identified from 14 different languages/cultures. Most reported forward and back translation and pretesting, but sample size was a problem for most studies. The Cronbach α was generally acceptable, and 13 versions met the criterion of reliability by reporting an intraclass correlation coefficient of 0.70 or more, although some versions did not reach the minimal intraclass correlation coefficient. Eleven versions tested ceiling and floor effects, but only 1 Japanese version reported a floor effect. No study reported interpretability, and none provided the minimal important change or minimal important difference.
  
  
  CONCLUSIONS
  The Arabic, Italian, and Thai versions were of higher quality than the other versions according to the overall assessment of the 3 checklists. The Catalan, Chinese, Japanese, Korean, Thai, and Turkish versions need more research according to the Quality Criteria for Psychometric Properties of Health Status Questionnaire. Pretest sample size was not large enough in most cases.
  
  
  METHODS
  1.
authors.affiliation: *Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China †Institute of Spine Disease, Shanghai University of Traditional Chinese Medicine, Shanghai, China ‡Yueyang College of Clinical Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China; and §Shanghai First People's Hospital, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Yue-li
authors.initials: YL
authors.lastname: Sun
authors.forename: Zuo-yuan
authors.initials: ZY
authors.lastname: Cao
authors.forename: Rong-liang
authors.initials: RL
authors.lastname: Dun
authors.forename: Long
authors.initials: L
authors.lastname: Yang
authors.forename: Bi-meng
authors.initials: BM
authors.lastname: Zhang
authors.forename: Hui-ru
authors.initials: HR
authors.lastname: Jiang
authors.forename: Yong-jun
authors.initials: YJ
authors.lastname: Wang
authors.forename: Xue-jun
authors.initials: XJ
authors.lastname: Cui
mesh_terms: D000069:Acculturation; D003431:Cross-Cultural Comparison; D004185:Disability Evaluation; D006304:Health Status; D006801:Humans; D007802:Language; D009043:Motor Activity / Q000502:physiology; D019547:Neck Pain / Q000175:diagnosis* / Q000503:physiopathology*; D011594:Psychometrics; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires