To assess changes measured with the Cochin rheumatoid arthritis (RA) hand functional disability scale during the course of the disease.
A cohort study evaluating outcome measure responsiveness in RA was conducted in a referral center. Ambulatory or hospitalized patients with RA according to the 1987 American College of Rheumatology (formerly the American Rheumatism Association) criteria were evaluated twice. Clinical measures included Cochin's scale, Revel's functional index, hand functional index, visual analog scale of patient-perceived handicap, visual analog scale of pain in hands and wrists, total score of swelling, total score of tenderness, and morning stiffness duration. Responsiveness was assessed by the effect size (ES) and the standardized response mean (SRM). The nonparametric Spearman rank correlation coefficient (r) was used to assess the correlation between two quantitative variable changes.
Fifty-five patients (44 women) were evaluated twice at an interval of 15.4 +/- 1.4 months (mean +/- SD) (range 13-18 months). The Cochin scale total score had worsened at the second visit (95% confidence interval for mean differences -5.16, 0.73). Its SRM and ES values were -0.20 and -0.15, respectively. Changes in the score had the highest correlation (r = 0.58) with changes in the patient-perceived handicap, while it had only fair or little correlation with changes in the disease activity measures. The factor 2 scale subscore significantly worsened and had the highest values of SRM and ES (SRM = -0.40 and ES = -0.31).
The Cochin scale can detect small but meaningful changes in RA hand disability.