Assessing arm and hand function after stroke: a validity test of the hierarchical scoring system used in the motor assessment scale for stroke.

OBJECTIVE To evaluate the validity of the scoring hierarchy for the 3 upper-limb items on the Motor Assessment Scale (MAS). DESIGN Application of Rasch analysis to 3 independent measurement scales, each representing the upper-arm function, hand movements, and advanced hand activities items of the MAS. SETTING Inpatient and outpatient occupational therapy (OT) programs in a department of rehabilitation of an urban hospital center. PARTICIPANTS One hundred patients (67 men, 33 women; average age, 54.3+/-14.4 y; average time since stroke onset, 104 d) attending OT for stroke rehabilitation. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURE The MAS for stroke (upper-arm function, hand movements, and advanced hand activities sections). RESULTS Rasch analysis provided support for the validity of hierarchical scoring criteria for the upper-arm scale. This analysis, however, identified inconsistencies in the hierarchical scoring criteria for the hand function and advanced hand activities scales and, when considering measurement error, only small differences in difficulty level between several behavioral criteria. CONCLUSIONS The findings lead to suggestions for changes in the behavioral criteria hierarchy for upper-limb items on the MAS and highlight the importance of using statistical analyses to test the validity of proposed hierarchies of behavioral criteria in functional assessments.