title: Validity and sensitivity to change of the NASS questionnaire for patients with cervical spine disorders.
abstract: METHODS
  Study of two cohorts with a differing severity of disease before and after treatment.
  
  
  OBJECTIVE
  The aim of this study was to examine the validity and sensitivity to change of the German version of the cervical NASS patient questionnaire.
  
  
  BACKGROUND
  To the authors' best knowledge, there are no data revealing the psychometric properties of the cervical NASS patient questionnaire.
  
  
  METHODS
  The validity and sensitivity in patients with cervical spine disorders who were referred by their physician either to an inpatient rehabilitation program or to an outpatient physiotherapy were examined. They were consecutively recruited. Their functioning and health status were assessed when entering the study and after the treatment by the NASS questionnaire and the Medical Outcome Survey Short Form-36 (SF-36).
  
  
  RESULTS
  Criterion validity was demonstrated by the statistically significant correlations between the NASS subscores and all subscores of SF-36. As expected, the SF-36 subscores Physical Function and Pain showed the strongest associations to the NASS subscore Pain and Disability (rho = 0.75 and 0.65, respectively), demonstrating construct validity of the latter. Discriminative validity of NASS subscores was shown in two ways. First, a statistically significant difference was found between functional and health status of the two cohorts with better scores in the patients referred to outpatient physiotherapy as compared with those sent to an inpatient rehabilitation program. Second, statistically significant and clinically important improvements recorded by the NASS subscores were demonstrated in both patient groups after the treatment in accordance with improved SF-36 subscores. Moreover, the NASS subscores demonstrated good sensitivity to change (Pain and Disability with a standard response mean ranging from 0.64 to 1.24).
  
  
  CONCLUSIONS
  The German version of the cervical NASS patient questionnaire (NASS) is a valid instrument for patients with cervical spine health problems. As this instrument is also sensitive to change, it is recommended for use. Moreover, the present study gives evidence for the validity of the original cervical NASS questionnaire in English.
authors.affiliation: Vereinigung der Rehabilitationskliniken der Schweiz, Schwiez, Switzerland. Thomas.Stoll@aarreha.ch
authors.forename: Thomas
authors.initials: T
authors.lastname: Stoll
authors.forename: Erika
authors.initials: E
authors.lastname: Huber
authors.forename: Stefan
authors.initials: S
authors.lastname: Bachmann
authors.forename: Hans-Ruedi
authors.initials: HR
authors.lastname: Baumeler
authors.forename: Stefan
authors.initials: S
authors.lastname: Mariacher
authors.forename: Martin
authors.initials: M
authors.lastname: Rutz
authors.forename: Werner
authors.initials: W
authors.lastname: Schneider
authors.forename: Hans
authors.initials: H
authors.lastname: Spring
authors.forename: André
authors.initials: A
authors.lastname: Aeschlimann
authors.forename: Gerold
authors.initials: G
authors.lastname: Stucki
authors.forename: Werner
authors.initials: W
authors.lastname: Steiner
mesh_terms: D002574:Cervical Vertebrae; D015331:Cohort Studies; D003431:Cross-Cultural Comparison; D004185:Disability Evaluation; D005858:Germany; D006304:Health Status; D006801:Humans; D019547:Neck Pain / Q000175:diagnosis* / Q000209:etiology / Q000534:rehabilitation; D017063:Outcome Assessment, Health Care; D010147:Pain Measurement; D011594:Psychometrics; D012680:Sensitivity and Specificity; D013122:Spinal Diseases / Q000150:complications / Q000175:diagnosis* / Q000534:rehabilitation; D011795:Surveys and Questionnaires