Evaluation of the core outcome measure in whiplash.
METHODS
Reanalysis of data derived from longitudinal cohort studies.


OBJECTIVE
To comprehensively evaluate the psychometric properties of a 5-item version of the Core Outcome Measure in people with whiplash.


BACKGROUND
The 7-item Core Outcome Measure was initially proposed as a brief health outcome measure for use in low back pain. To date, this measure has not been comprehensively assessed in a whiplash population. METHOD.: Data were sourced from 3 separate whiplash cohorts (total 481) encompassing acute, early chronic, and late-chronic whiplash among primary care and insurance populations. Subjects completed a 5-item version of the Core Outcome Measure for whiplash (Core Whiplash Outcome Measure [CWOM]), the Functional Rating Index, Neck Disability Index, SF-36, and perceived recovery questionnaires at baseline and short and long-term follow-up periods. Psychometric evaluation of the CWOM included assessing questionnaire responses, internal consistency, construct validity, and internal and external responsiveness.


RESULTS
Internal consistency was excellent at all stages of whiplash (Cronbach alpha = 0.76 in the acute stage and 0.83 in the late-chronic stage). Convergent validity was observed between the CWOM and Functional Rating Index (Pearson r = 0.81), Neck Disability Index (Pearson r = 0.76), and SF-36 physical health summary measure (Pearson r = -0.65). Divergent validity was observed between the CWOM and SF-36 mental health summary measure (Pearson r = -0.45). The internal and external responsiveness of the CWOM was similar to other neck-specific outcome measures.


CONCLUSIONS
We recommend the 5-item CWOM as a brief clinical measure for whiplash because it is quick to administer and score, and has excellent measurement properties. The CWOM may need to be supplemented with other questionnaires (e.g., when assessment of psychological or emotional health is required).
Rebbeck
Trudy J
TJ
Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, New South Wales, Australia. T.Rebbeck@usyd.edu.au
Refshauge
Kathryn M
KM
Maher
Christopher G
CG
Stewart
Mark
M
D000328:Adult; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D017116:Low Back Pain / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D014911:Whiplash Injuries / Q000150:complications* / Q000175:diagnosis / Q000628:therapy