Ann Rehabil Med.  2018 Oct;42(5):690-701. 10.5535/arm.2018.42.5.690.

A New Functional Scale and Ambulatory Functional Classification of Duchenne Muscular Dystrophy: Scale Development and Preliminary Analyses of Reliability and Validity

• Kim J
• Jung IY
• Kim SJ
• Lee JY
• Park SK
• Shin HI
• Bang MS

• KMID: 2429198
• DOI: http://doi.org/10.5535/arm.2018.42.5.690

Abstract

OBJECTIVE
To develop a simplified functional scale and classification system to evaluate the functional abilities of patients with Duchenne muscular dystrophy (DMD).
METHODS
A Comprehensive Functional Scale for DMD (CFSD) was developed using the modified Delphi method. The accompanying Ambulatory Functional Classification System for DMD (AFCSD) was developed based on previously published classification systems.
RESULTS
The CFSD consists of 21 items and 78 sub-items, assessing body structure and function, activities, and participation. Inter-rater intraclass correlation coefficient values were above 0.7 for 17 items. The overall limits of agreement between the two examiners ranged from -6.21 to 3.11. The Spearman correlation coefficient between the total score on the AFCSD and the Vignos Functional Scale was 0.833, and 0.714 between the total score of the AFCSD and the Brooke scale. Significant negative correlations existed between the total score for each functional level of the AFCSD and each functional grade of the Vignos and Brooke scales. The total scores of the CFSD varied significantly between the functional grades of the Vignos scale, and specific grades of the Brooke scale. For the AFCSD, total scores of the CFSD varied significantly between the functional levels.
CONCLUSION
We have developed a new scale and the associated classification system, to assess the functional ability of children diagnosed with DMD. Preliminary evaluation of the psychometric properties of the functional scale and classification systems indicate sufficient reliability and concurrent validity.

Keyword

Duchenne muscular dystrophy; Functional scale; Ambulatory function; Scale development

MeSH Terms

Child
Classification*
Humans
Methods
Muscular Dystrophy, Duchenne*
Psychometrics
Reproducibility of Results*
Weights and Measures

Figure

• 

  Fig. 1. Ambulatory functional classification system for Duchenne muscular dystrophy (DMD).

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  Fig. 2. Bland-Altman plot for agreements between examiners 1 and 2 in the ambulatory functional classification system for Duchenne muscular dystrophy (AFCSD). Blue horizontal lines show a 97.5% limit, median, and 2.5% limit of the agreements.

• 

  Fig. 3. Bland-Altman plot for agreements between examiners 1 and 2 in the total score of the new functional scale. (A) Total score ranging from item 1 to 19; (B) items with acceptable (>0.7) intraclass correlation coefficients. Blue horizontal lines show a 97.5% limit, median, and 2.5% limit of the agreements.

• 

  Fig. 4. Total scores of the comprehensive functional scale under each grade: (A) Vignos scale, and (B) Brooke scale. In the Vignos scale, scores varied significantly between grades 1–2, 1–4, 1–9, 2–9, 3–9, and 4–9. In the Brooke scale, scores between grade 2 and 3 differ from each other. Lower and upper margins of the box present the lower quartile (Q1) and the upper quartile (Q3) of the total score. The band inside the box indicates median, and the whiskers range from Q1+1.5 interquartile range (IQR) to Q3+IQR. Hollow circles represent outliers. Horizontal lines above the box graph depict significant differences in the Wilcoxon rank sum test (adjusted p<0.05).

• 

  Fig. 5. Total scores in each level of the ambulatory functional classification system for Duchenne muscular dystrophy (AFCSD). Significant differences in the total score were found between 1–5, and 2–5. Lower and upper margins of the box present the lower quartile (Q1) and the upper quartile (Q3) of the total score. The band inside the box indicates median, and the whiskers range from Q1+1.5 interquartile range (IQR) to Q3+IQR. Hollow circles show outliers. Horizontal lines above the box graph depict significant differences in the Wilcoxon rank sum test (adjusted p<0.05).

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