Clinically Important Difference of the Arm Motor Ability Test in Stroke Survivors

Abstract

Background. The Arm Motor Ability Test (AMAT) is used to assess and quantify upper-extremity (UE) functional limitation in stroke and other conditions. However, the AMAT score change indicative of important and clinically meaningful change has not been determined. Objective. To determine the clinically important difference (CID) for the AMAT for individuals with stroke exhibiting mild to moderate hemiparesis. Methods. A total of 146 chronic stroke survivors exhibiting stable, mild to moderate UE hemiparesis were administered the AMAT before and after interventions targeting their affected UEs. Patients and treating therapists rated perceived amount of UE motor recovery for each participant on a global rating of change (GROC) scale evaluating several facets of UE movement (grasp, release, move the affected UE, perform 5 important functional tasks, overall UE function). Estimated CID of the Functional Ability Scale of the AMAT was calculated using the receiver operating characteristics curve with the GROC scale as the anchor. Distribution-based methods were also used to estimate the CID. Results. Mean baseline, postintervention, and change in AMAT values for all participants were 3.0 (0.68), 3.3 (0.73), and 0.33 (0.43) respectively. The CID was estimated as an improvement of 0.32 to 0.42 when anchored by the therapist’s perception of improvement and 0.29 to 0.40 when anchored by the patient’s perception of improvement. The CID using distribution-based methods ranged from 0.40 to 0.44. Conclusions. A change of 0.44 or greater on the AMAT indicates a clinically meaningful improvement in UE functional movements. Clinicians should use this value to determine goals and interpret change scores.