Estimating minimal clinically important differences of upper-extremity measures early after stroke

Abstract

Objective: To estimate minimal clinically important difference (MCID) values of several upper-extremity measures early after stroke.

Design: Data in this report were collected during the Very Early Constraint-induced Therapy for Recovery of Stroke trial, an acute, single-blind randomized controlled trial of constraint-induced movement therapy. Subjects were tested at the prerandomization baseline assessment (average days poststroke, 9.5d) and the first posttreatment assessment (average days poststroke, 25.9d). At each time point, the affected upper extremity was evaluated with a battery of 6 tests. At the second assessment, subjects were also asked to provide a global rating of perceived changes in their affected upper extremity. Anchor-based MCID values were calculated separately for the affected dominant upper extremities and the affected nondominant upper extremities for each of the 6 tests.

Setting: Inpatient rehabilitation hospital.

Participants: Fifty-two people with hemiparesis poststroke.

Interventions: Not applicable.

Main outcome measures: Estimated MCID values for grip strength, composite upper-extremity strength, Action Research Arm Test (ARAT), Wolf Motor Function Test (WMFT), Motor Activity Log (MAL), and duration of upper-extremity use as measured with accelerometry.

Results: MCID values for grip strength were 5.0 and 6.2 kg for the affected dominant and nondominant sides, respectively. MCID values for the ARAT were 12 and 17 points, for the WMFT function score were 1.0 and 1.2 points, and for the MAL quality of movement score were 1.0 and 1.1 points for the 2 sides, respectively. MCID values were indeterminate for the dominant (composite strength), the nondominant (WMFT time score), and both affected sides (duration of use) for the other measures.

Conclusions: Our data provide some of the first estimates of MCID values for upper-extremity standardized measures early after stroke. Future studies with larger sample sizes are needed to refine these estimates and to determine whether MCID values are modified by time poststroke.

Figure 1

Frequency of subjects’ perceived change ratings. Subjects are grouped by whether the dominant or the non-dominant upper extremity was affected by the stroke. Perceived change ratings: 1 = Much better; 2 = A little better, meaningful; 3 = A little better, not meaningful; 4 = About the same; 5 = A little worse, not meaningful; 6 = A little worse, meaningful; 7 = Much worse.

Figure 2

Mean change scores in impairment level measures by perceived change ratings and upper extremity affected. Error bars represent standard errors. A: Grip strength in the affected hand, measured in kgs as part of the Wolf Motor Function Test. B: Composite upper extremity strength on the affected side; values are expressed as ratios of the unaffected upper extremity. Perceived change ratings: 1 = Much better; 2 = A little better, meaningful; 3 = A little better, not meaningful; 4 = About the same.

Figure 3

Mean change scores in activity level measures by perceived change ratings and upper extremity affected. Error bars represent standard errors. A: Action Research Arm Test. B: Wolf Motor Function Test Time score. C: Wolf Motor Function Test Function score. Perceived change ratings: 1 = Much better; 2 = A little better, meaningful; 3 = A little better, not meaningful; 4 = About the same.

Figure 4

Mean change scores in participation level measures by perceived change ratings and upper extremity affected. Error bars represent standard errors. A: Motor Activity Log How well score. B: Duration of affected upper extremity use, measured by wrist accelerometers and expressed in hours. Perceived change ratings: 1 = Much better; 2 = A little better, meaningful; 3 = A little better, not meaningful; 4 = About the same.