Dr. Dougados has received consulting fees and/or honoraria (less than $10,000) from Merck Sharp & Dohme-Chibret Laboratories.
Validation of a short form of the Western Ontario and McMaster Universities Osteoarthritis Index function subscale in hip and knee osteoarthritis
Article first published online: 30 APR 2007
Copyright © 2007 by the American College of Rheumatology
Arthritis Care & Research
Volume 57, Issue 4, pages 633–638, 15 May 2007
How to Cite
Baron, G., Tubach, F., Ravaud, P., Logeart, I. and Dougados, M. (2007), Validation of a short form of the Western Ontario and McMaster Universities Osteoarthritis Index function subscale in hip and knee osteoarthritis. Arthritis & Rheumatism, 57: 633–638. doi: 10.1002/art.22685
- Issue published online: 30 APR 2007
- Article first published online: 30 APR 2007
- Manuscript Accepted: 28 SEP 2006
- Manuscript Received: 21 MAR 2006
- Merck Sharp & Dohme Chibret Laboratories, Paris, France
- Western Ontario and McMaster Universities Osteoarthritis Index function;
- Short form;
A short version of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function scale has recently been developed to enhance the applicability of the scale in routine practice and clinical research for patients with hip and knee osteoarthritis. The goal of the present study was to validate this short form.
We conducted a prospective 4-week cohort study of 1,036 outpatients. Performance on the WOMAC function long form (LF) and short form (SF) was compared. Agreement between responses on the 2 forms was examined according to a Bland-Altman plot. Responsiveness to change (by standardized response mean [SRM]), reproducibility (intraclass correlation coefficient [ICC]), and internal consistency (Cronbach's alpha) were computed for both forms. Construct validity was assessed based on functional impairment as measured on a numerical rating scale.
At baseline, 24% of patients who completed the WOMAC LF had missing data for at least 1 item as compared with only 6% of patients who completed the WOMAC SF. The mean WOMAC SF score was greater than the mean WOMAC LF score (mean ± SD difference −4.3 ± 4.8 on a 0–100 scale). SRMs were 0.61 and 0.73, ICCs were 0.76 and 0.68, and Cronbach's alphas were 0.93 and 0.85 for the WOMAC LF and SF, respectively. The 2 forms had comparable correlation with functional impairment.
The WOMAC function short form has a low rate of missing data and is a responsive, reproducible, and valid measure. The mean SF score was 4 points higher than the mean LF score.