Disability in subacute whiplash patients: usefulness of the neck disability index.
METHODS
Cross-sectional study.


OBJECTIVE
To analyze the psychometric properties of the neck disability index (NDI), with a special emphasis in its factor structure, and its usefulness, in a sample of patients suffering from a subacute whiplash problem.


BACKGROUND
A valid and reliable instrument to assess pain-related disability would be of great help to clinicians and researchers interested in whiplash associated disorders. First, to better understand the impact of whiplash on the patient's life, and his or her progress over time. Second, to formulate comprehensive treatment plans, and evaluate the results from therapeutic actions. Finally, to follow-up patients' changes and improvement. The NDI could be an appropriate instrument for these purposes.


METHODS
A convenience sample of 150 subacute whiplash patients participated. They were requested to complete the Catalan version of the NDI, and report about their pain intensity, pain interference and depression. RESULTS.: An exploratory factor analysis showed that the NDI can be viewed as a 2-factor instrument. The items and the instrument's total score were normally distributed. Internal consistency was also appropriate both for the total score (Cronbach's alpha: 0.87) and the 2 subscales (0.7 for the pain and interference with cognitive functioning scale, and 0.83 for the physical functioning scale). Total NDI and subscales scores significantly correlated with pain intensity, pain interference, and depression.


CONCLUSIONS
The NDI showed excellent psychometric properties in a sample of subacute whiplash patients. Additional research is needed to replicate the NDIs factor structure.
Nieto
Rubén
R
Department of Psychology and Education, Open University of Catalonia, Universitat Oberta de Catalunya, Barcelona, Spain. rnietol@uoc.edu
Miró
Jordi
J
Huguet
Anna
A
D000208:Acute Disease; D000328:Adult; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019838:Neck Injuries / Q000175:diagnosis / Q000473:pathology; D010147:Pain Measurement / Q000379:methods / Q000592:standards; D012720:Severity of Illness Index; D014911:Whiplash Injuries / Q000175:diagnosis* / Q000473:pathology