Validity and sensitivity to change of the NASS questionnaire for patients with cervical spine disorders.
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.
Stoll
Thomas
T
Vereinigung der Rehabilitationskliniken der Schweiz, Schwiez, Switzerland. Thomas.Stoll@aarreha.ch
Huber
Erika
E
Bachmann
Stefan
S
Baumeler
Hans-Ruedi
HR
Mariacher
Stefan
S
Rutz
Martin
M
Schneider
Werner
W
Spring
Hans
H
Aeschlimann
André
A
Stucki
Gerold
G
Steiner
Werner
W
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