Determining Levels of Upper Extremity Movement Impairment by Applying a Cluster Analysis to the Fugl-Meyer Assessment of the Upper Extremity in Chronic Stroke

Abstract

Objective: To quantitatively determine levels of upper extremity movement impairment by using a cluster analysis of the Fugl-Meyer Assessment of the Upper Extremity (FMA-UE) with and without reflex items.

Design: Secondary analysis.

Setting: University and research centers.

Participants: Individuals (N=247) with chronic stroke (>6mo poststroke).

Interventions: Not applicable.

Main outcome measures: Cutoff scores defined by FMA-UE total scores of clusters identified by 2 hierarchical cluster analyses performed on the full sample of FMA-UE individual item scores (with and without reflexes). Patterns of motor function defined by aggregate item scores of clusters.

Results: FMA-UE scores ranged from 2 to 63 (mean, 26.9±15.7) with reflex items and from 0 to 57 (mean, 22.1±15.3) without reflex items. Three clusters were identified. The distributions of the FMA-UE scores revealed considerable overlap between the clusters; therefore, 4 distinct stroke impairment levels were derived.

Conclusions: For chronic stroke, the cluster analysis of the FMA-UE supports either a 3- or a 4-impairment level classification scheme.

Keywords: Cluster analysis; Rehabilitation; Stroke; Upper extremity.

Copyright © 2016 American Congress of Rehabilitation Medicine. All rights reserved.

Figures

Figure 3. Individual Item Scores of 3-Group Impairment Levels

Percentage of FM-UE scores of all individuals in each impairment level are displayed for each item as black, grey, and white for scores of 0, 1, and 2, respectively. Numbers 1–33 along the horizontal axis of each histogram correspond to each individual item of the assessment detailed in the item key at the bottom of the figure. Although the cluster analysis did not include the reflex items, the reflex item scores were included in the figure to describe the patients included in these groups based on all of their individual item scores

Figure 1. Cluster FM-UE Distributions

Cluster 1, 2, and 3 are indicated from dark to light respectively. Red lines correspond to the normal distribution of each cluster. Vertical blue lines represent the FM-UE cut scores of the subsequently identified 3-group (A) and 4-group (B) division of impairment levels. As the characteristics of the distributions of the 3 clusters were used to determine the new cut points displayed in Figure 1.B, the original distributions of the 3 clusters were retained in Figure 1.B. in order to graphically depict this relationship between the clusters and new cut points.

Figure 2. Individual Item Scores of 4-Group Impairment Levels

Percentage of FM-UE scores of all individuals in each impairment level are displayed for each item as black, grey, and white for scores of 0, 1, and 2, respectively. Numbers 1–33 along the horizontal axis of each histogram correspond to each individual item of the assessment detailed in the item key at the bottom of the figure. Although the cluster analysis did not include the reflex items, the reflex item scores were included in the figure to describe the patients included in these groups based on all of their individual item scores