Ambulatory monitoring of arm movement using accelerometry: An objective measure of upper-extremity rehabilitation in persons with chronic stroke

Objective: To evaluate the reliability and validity of accelerometry for measuring upper-extremity rehabilitation outcome. Design: Validation study. Setting: Data recorded in the community. Participants: Consecutive Constraint-Induced Movement therapy (CIMT) patients (n=10) and volunteer community residents with stroke (n = 10). All participants were more than I year poststroke and had mild to moderate motor impairment of the more affected arm. Intervention: All study participants were asked to wear accelerometers outside the laboratory for 3 days immediately before and after treatment, or for an approximately equivalent no-treatment period (controls). Main Outcome Measures: Participants wore an accelerometer on each arm, the chest, and the more affected leg and completed the Motor Activity Log (MAL), which is a semi-structured interview of real-world arm use. Results: Test-retest reliability of transformed accelerometer recordings was greater than .86. There was also a large increase in the ratio of transformed more- to less-impaired arm recordings in CIMT therapy patients (d'=0.9, P <.05), while there was no change for controls. The correlation between this parameter and the MAL was .74 (P <.001). Conclusions: Accelerometry provides an objective, realworld index of upper-extremity rehabilitation outcome and has good psychometric properties.