To assess the responsiveness of the Cochin functional disability scale for the rheumatoid hand after surgery.
In a prospective study, patients with rheumatoid arthritis (RA) scheduled for surgery of the wrist and/or fingers were evaluated within 48 h before surgery and at least 6 months after surgery. Clinical outcome measures included duration of morning stiffness, total score for tenderness, total score for swelling, visual analogue scale score for pain in the hands and wrists, a score for overall mobility of the wrist and the fingers, grip and pinch strength, the Hand Functional Index (HFI), the Kapandji index and the Cochin scale. Responsiveness was assessed with the paired t-test, the effect size (ES), the standardized response mean (SRM) and the non-parametric Spearman rank correlation coefficient (r(S)).
Fifty patients (42 women) were evaluated twice at an interval of 7.16 +/- 2.10 months (mean +/- s.d.) (range 6-15 months). Thirty-six patients (72%) were very satisfied or satisfied with the results of surgery, seven (14%) were not satisfied or dissatisfied and seven (14%) were dissatisfied or very dissatisfied. The Cochin scale score improved at the second visit (P < 0.0001), with SRM and ES values of 0.66 and 0.58 respectively. The correlation of the change in Cochin score with patient overall satisfaction was r(S) = 0.40. Among the impairment measures, grip strength showed the best responsiveness (SRM = - 0.43, ES = - 0.36, correlation with patient overall satisfaction r(S) = 0.46). The change in Kapandji index had the best correlation (r(S) = 0.51) with patient overall satisfaction but its SRM and ES values were low (- 0.19 and - 0.10 respectively).
The Cochin scale is responsive and appropriate for the assessment of the effects of surgical treatments on disability in RA hands.