Validity of accelerometry for monitoring real-world arm activity in patients with subacute stroke: evidence from the extremity constraint-induced therapy evaluation trial.

OBJECTIVE

To examine the psychometric properties of an objective method for assessing real-world arm activity in a large sample with subacute stroke.

DESIGN

Validation study.

SETTING

Community.

PARTICIPANTS

Persons 3 to 9 months poststroke (N=169) with mild to moderate motor impairment of their hemiparetic arm enrolled in a multisite, randomized clinical trial of constraint-induced movement therapy.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participants wore an accelerometer on each arm outside the laboratory for 3 days before and after treatment or an equivalent no-treatment period. They also completed the Actual Amount of Use Test (AAUT), which is an observational measure of spontaneous more-impaired arm use, and the Motor Activity Log (MAL), which is an interview assessing more-impaired arm use in daily life.

RESULTS

Low-pass-filtered accelerometer recordings were reliable (r range, >.8) and stable (P range, >.48). Their validity was also supported. Correlations calculated across all participants at baseline between the ratio of more-impaired to less-impaired arm accelerometer recordings and AAUT and MAL scores were .60 and .52, respectively.

CONCLUSIONS

Accelerometry provides an objective, real-world index of more-impaired arm activity with good psychometric properties.