Minimal detectable change and clinically important difference of the Wolf Motor Function Test in stroke patients

Area of Science:

• Neurology
• Rehabilitation Medicine
• Biostatistics

Background:

• Stroke significantly impairs motor function, necessitating reliable outcome measures for rehabilitation.
• The Wolf Motor Function Test (WMFT) is widely used, but its minimal detectable change (MDC) and clinically important differences (CID) require precise definition for stroke patients.

Purpose of the Study:

• To establish the MDC and CID for the WMFT in stroke patients undergoing rehabilitation.
• To determine the proportion of patients whose change scores exceed these thresholds.

Main Methods:

• 57 stroke patients received 3 weeks of treatment, with WMFT assessments pre- and post-intervention.
• MDC(90) was calculated using the standard error of measurement.
• Anchor-based and distribution-based methods were used to determine minimal CID.

Main Results:

• MDC(90) was 4.36 for WMFT performance time and 0.37 for WMFT functional ability scale (FAS).
• Minimal CID ranged from 1.5-2 seconds (WMFT time) and 0.2-0.4 points (WMFT FAS).
• Proportions exceeding MDC/CID were 14-30% (WMFT time) and 39-65% (WMFT FAS).

Conclusions:

• A change score of 4.36 (WMFT time) or 0.37 (WMFT FAS) indicates a real change for individual stroke patients.
• Clinically important changes are 1.5-2 seconds (WMFT time) and 0.2-0.4 points (WMFT FAS).
• WMFT FAS demonstrates greater responsiveness compared to WMFT time in this stroke cohort.