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Mitochondrial Myopathy Composite Assessment Tool (MM-COAST)
Availability
Please email the author for information about obtaining the instrument: Contact Children's Hospital of Philadelphia Research Institute Office of Technology Transfer Team, Arshdeep Sidhu sidhua@chop.edu
Classification
Supplemental - Highly Recommended: Mitochondrial Disease (Mito)
Recommendations for use: Indicated for longitudinal and exercise studies.
Short Description of Instrument
The MM-Coast is a validated, clinically meaningful measure that evaluates the core domains of muscle strength, muscle fatigue, imbalance, exercise intolerance and dexterity in individuals diagnosed with mitochondrial myopathy (MM).
 
The five domains measured in order of assessment are Muscle Strength (4 muscle groups tested via hand-held dynamometry for muscle strength) (Beenakker et al., 2001; Phillips et al., 2000; Mathiowetz et al., 1986; Mathiowetz et al., 1985), Muscle Fatigue (one muscle group via dynamometry) (Flickinger et al., 2021), Balance Testing (3 static positions) (McKay et al., 2017), Exercise Intolerance (30 second Sit to Stand and 6 Minute Walk Test) (McKay et al., 2017; Montes et al., 2010), Dexterity (Nine Hole Peg Test and Functional Dexterity Test) (McKay et al., 2017).
Comments/Special Instructions
The MM-COAST is a validated outcome measure designed to quantify the key domains of mitochondrial myopathy. Each domain yields a domain score based upon how patients score on individual tests compared to normative population (z-score). A total composite score can then be calculated to represent overall disease severity.
Scoring and Psychometric Properties
Scoring: Each individual test is scored based upon select normative data protocols. Dominant side z-score (or percent decrement for muscle fatigue) is calculated using formulas provided for each raw score. Based upon their z-score and percent decrement, a test score is given ranging from -3 to +3 using provided chart. The test scores are summed and divided by the number of tests in each domain to provide domain scores. These domain scores are then summed and divided by the number of completed domains yielding the MM-COAST composite score.
 
For ambulatory individuals: All 5 domains are recommended but at least 3 domains must be completed for a composite score.
 
For non-ambulatory individuals: 3 domains are recommended but at least 2 domains must be completed for a composite score.
 
Psychometric Properties: The MM-COAST is a validated outcome measure for use in primary mitochondrial disease, specifically mitochondrial myopathy. Test-re-test reliability revealed a good ICC 0.81 (95% CI: 0.59-0.92) in a mitochondrial myopathy cohort and an assessment of internal consistency revealed an acceptable Cronbach's alpha of 0.67 across all 5 domains. A moderate correlation to the North Star Ambulatory Assessment was observed with MM-COAST Composite scores (r= -0.64, p<0.0001, n=52), providing evidence of the clinical meaning of the MM-COAST.
Rationale/Justification
Mitochondrial Disease-Specific: The MM-COAST was designed specifically to measure symptoms common in mitochondrial disease.
 
Strengths: The MM-COAST is a validated, objective outcome measure that can be used for both ambulatory and non-ambulatory individuals and can be completed in approximately 60-75 minutes. It has been designed to capture key symptoms of mitochondrial myopathy including deficits in strength, muscle fatigue, balance, exercise intolerance, and dexterity. The MM-COAST is clinically meaningful and can objectively measure top symptoms reported by individuals with mitochondrial disease and has been validated for use in mitochondrial myopathy. It includes a novel objective measure of muscle fatigue using dynamometry. Data can be analyzed based upon individual test z-scores, domain scores, as well as a total composite score. Scoring provides quantitative measures to discriminate the relative contributions of core domains on individual patient function and also provides an overall score of disease severity. This data tracked over time can be useful in informing clinical care, and in longitudinal studies and intervention trials.
 
Weaknesses: Requires trained physical therapist or clinician to administer the assessment.
References
Key Reference:
Flickinger J, Fan J, Wellik A, Ganetzky R, Goldstein A, Muraresku CC, Glanzman AM, Ballance E, Leonhardt K, McCormick EM, Soreth B, Nguyen S, Gornish J, George-Sankoh I, Peterson J, MacMullen LE, Vishnubhatt S, McBride M, Haas R, Falk MJ, Xiao R, Zolkipli-Cunningham Z. Development of a Mitochondrial Myopathy-Composite Assessment Tool. JCSM Clin Rep. 2021 Oct;6(4):109-27.
 
Additional References:
Beenakker EA, van der Hoeven JH, Fock JM, Maurits NM. Reference values of maximum isometric muscle force obtained in 270 children aged 4-16 years by hand-held dynamometry. Neuromuscul Disord. 2001 Jul;11(5):441-6.
 
Mathiowetz V, Wiemer DM, Federman SM. Grip and pinch strength: norms for 6- to 19-year-olds. Am J Occup Ther. 1986 Oct;40(10):705-11.
 
Mathiowetz V, Kashman N, Volland G, Weber K, Dowe M, Rogers S. Grip and pinch strength: normative data for adults. Arch Phys Med Rehabil. 1985 Feb;66(2):69-74.
 
McKay MJ, Baldwin JN, Ferreira P, Simic M, Vanicek N, Burns J; 1000 Norms Project Consortium. Reference values for developing responsive functional outcome measures across the lifespan. Neurology. 2017 Apr 18;88(16):1512-1519.
 
Montes J, McDermott MP, Martens WB, Dunaway S, Glanzman AM, Riley S, Quigley J, Montgomery MJ, Sproule D, Tawil R, Chung WK, Darras BT, De Vivo DC, Kaufmann P, Finkel RS; Muscle Study Group and the Pediatric Neuromuscular Clinical Research Network. Six-Minute Walk Test demonstrates motor fatigue in spinal muscular atrophy. Neurology. 2010 Mar 9;74(10):833-8.
 
Phillips BA, Lo SK, Mastaglia FL. Muscle force measured using "break" testing with a hand-held myometer in normal subjects aged 20 to 69 years. Arch Phys Med Rehabil. 2000 May;81(5):653-61.
 
Document last updated March 2024