title: Cross-cultural adaptation and validation of the Brazilian Portuguese version of the Neck Disability Index and Neck Pain and Disability Scale.
abstract: METHODS
  This study's design was a cross-cultural validation of the Neck Disability Index and Neck Pain and Disability Scale.
  
  
  OBJECTIVE
  This study's objective was to translate, culturally adapt, and validate a Brazilian Portuguese version of the Neck Disability Index (NDI-BR) and the Neck Pain and Disability Scale (NPDS-BR).
  
  
  BACKGROUND
  Although several valid measures exist for measurement of neck pain and functional impairment, these measures have yet been validated in Brazilian Portuguese. Successful linguistic and cultural translation may allow appropriate cross-cultural comparison for clinical and laboratory research analysis.
  
  
  METHODS
  The NDI-BR and NPAD-BR were culturally and linguistically translated from English into Brazilian Portuguese. The translated version of the instrument was administered to 203 patients at a midsize hospital in southern Brazil. Psychometric evaluation included factor analysis, internal reliability measures, test-retest reliability at 1 and 7 days, and criterion validity comparison with the Brazilian version of the SF-36.
  
  
  RESULTS
  Factor analyses demonstrated a single-factor subscale for the NDI-BR and three subscales for the NPDS-BR. An item analysis showed a high degree of internal consistency for the NDI-BR (r = 0.74) and the three subscales of the NPDS-BR (subscale 1, r = 0.89; subscale 2, r = 0.81; subscale 3, r = 0.72). Test-retest reliability was also acceptable at for the NDI-BR (0.98 at baseline and 0.48 at 7 days) and subset one (0.96 at baseline and 0.91 at 7 days), subset 2 (0.96 at baseline and 0.62 at 7 days), and subset 3 (0.52 at baseline and 0.45 at 7 days) of the NPDS-BR. Construct validity was established during comparison of the Brazilian version of the SF-36. Only items associated with physical role, bodily pain, and emotional role failed significant correlation.
  
  
  CONCLUSIONS
  A reliable and valid Portuguese version of the Neck Disability Index and Neck Pain and DisabilityScale was developed, which will facilitate the examination of functional performance within a large patient population, as well as cross-cultural comparisons.
authors.affiliation: Division of Physical Therapy, Duke University Medical Center, Durham, NC 27710, USA. chad.cook@duke.edu
authors.forename: Chad
authors.initials: C
authors.lastname: Cook
authors.forename: Jan K
authors.initials: JK
authors.lastname: Richardson
authors.forename: Larissa
authors.initials: L
authors.lastname: Braga
authors.forename: Andreia
authors.initials: A
authors.lastname: Menezes
authors.forename: Xavier
authors.initials: X
authors.lastname: Soler
authors.forename: Paulo
authors.initials: P
authors.lastname: Kume
authors.forename: Marcelo
authors.initials: M
authors.lastname: Zaninelli
authors.forename: Fernanda
authors.initials: F
authors.lastname: Socolows
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pietrobon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil / Q000208:ethnology; D003466:Cultural Characteristics; D004185:Disability Evaluation; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000503:physiopathology*; D011174:Portugal; D011795:Surveys and Questionnaires / Q000592:standards*