Minimal Detectable Change and Clinically Important Difference of the Wolf Motor Function Test in Stroke Patients

Objectives. This study aimed to establish the minimal detectable change (MDC) and clinically important differences (CID) of the Wolf Motor Function Test (WMFT) in patients with stroke, and to assess the proportions of patients' change scores exceeding the MDC and CID after stroke rehabilitation. Methods. A total of 57 patients received 1 of the 3 treatments for 3 weeks and underwent clinical assessments before and after treatment. The MDC, at 90% confidence (MDC90), was calculated from the standard error of measurement to indicate a real change for individual patients. Anchor-based and distribution-based approaches were used to triangulate the values of minimal CID. The percentages of patients exceeding the MDC and minimal CID were also examined. Results. The MDC90 of the WMFT was 4.36 for the performance time (WMFT time) and 0.37 for the functional ability scale (WMFT FAS). The minimal CID ranged from 1.5 to 2 seconds on the WMFT time and from 0.2 to 0.4 points on the WMFT FAS. The MDC and CID proportions ranged from 14% to 30% on the WMFT time and from 39% to 65% on the WMFT FAS, respectively. Conclusions. The change score of an individual patient has to reach 4.36 and 0.37 on the WMFT time and WMFT FAS to indicate a real change. The mean change scores of a stroke group on the WMFT time and WMFT FAS should achieve 1.5 to 2 seconds and 0.2 to 0.4 points to be regarded as clinically important changes. Furthermore, the WMFT FAS may be more responsive than the WMFT time based on the results of proportions exceeding the threshold criteria.