Can the Wolf Motor Function Test be streamlined

Stroke is the leading cause of adult disability and also the third leading cause of death in the United States.1 Over the past 30 years, mortality from stroke has declined, resulting in an increasing number of patients receiving rehabilitation.2 Residual upper extremity (UE) hemiparesis persists long after the initial stroke in 50% of stroke survivors,3 and a considerable rehabilitative effort is required to maximize functional potential. Among the many outcome measures to assess UE capabilities following stroke, the Wolf Motor Function Test (WMFT), a laboratory-based test, measures time to complete 15 UE tasks and 2 strength tasks. The WMFT is typically administered to patients with mild to moderate stroke4 to assess the impact of specific interventions, such as constraint-induced movement therapy (CIMT),5 functional electric stimulation-assisted exercise therapy (FES-ET),6 robotic therapy,7 and repetitive bilateral arm training with rhythmic auditory cueing (BATRAC).8 The reliability9 and validity4,10,11 of the WMFT have been confirmed in previous studies. Unlike other assessments for stroke, the WMFT tests a wide variety of tasks (progressing from simple to complex) and is composed of 3 parts: (1) time, the speed of the completion of the tasks; (2) functional ability, the quality of movement during the task; and (3) strength.12 The progressive tasks are relative to the number of joints used to perform the task, beginning with selective activation at the shoulder joint to complex but functionally relevant movements. The primary outcome measure is the mean or log mean WMFT score for the 15 timed tasks, keeping the 2 strength task scores separate.13 Because of the skewed distribution of normative data,10,14 the transformed log mean of the WMFT has also been used to describe the data5 and in performing statistical analyses. This test can differentiate patients who are considered higher or lower functioning among those individuals with mild to moderate stroke as defined by wrist and digit active range of motion.13 Moreover, the test is not influenced by whether the affected limb is dominant; however, women tend to exhibit slower performance times than men.10 The WMFT was used as a primary outcome measure in the Extremity Constraint Induced Therapy Evaluation (EXCITE) trial, whose primary outcomes5 and protocol have been detailed elsewhere.13 This randomized clinical trial demonstrated that CIMT produced greater functional changes in patients with subacute stroke (3–9 months) than did usual and customary care, and that both higher and lower functioning participants could improve significantly. Both the WMFT and the Motor Activity Log (MAL), a survey that measures everyday activities, and the Stroke Impact Scale, a measure of health related quality of life,5 were used for assessment in this trial. Because of the substantive improvements seen on the WMFT by EXCITE participants, efforts to determine if there is an association between the magnitude of improvement on any 1 task and the change score on all other tasks among participants receiving CIMT immediately or 1 year after enrollment seemed reasonable. The high interrater reliability and validity of the WMFT serve as the foundation for this evaluation. The purpose of the present study was to potentially streamline the WMFT by defining only those tasks that showed the greatest improvement relative to the overall WMFT change score. Such streamlining is important because it could reduce the time necessary to administer the test (time to administer the WMFT ranges from 30–45 minutes) and provide the most pertinent information about recovery potential to the clinician, since tasks are targeted to demonstrate movement contributions from specific joints. This study also examined the extent to which this association is modified by time poststroke after controlling for key variables including functional level, gender, and concordance.