Résumé :
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The ideal scale for the assessment of a patient with a neuromuscular disorder incorporates functionally meaningful items, can be administered briefly and without expensive equipment by trained evaluators, is sensitive to change within a six to twelve month interval, has good inter- and intra-rater reliability and has been validated for the disease under study. For such a scale to be useful as an outcome measure in a clinical trial it should be predictive of an event, e.g. time to death, dependence upon bi-PAP, loss of ambulation. This permits response to an intervention (drug, surgical procedure) to be interpreted as having true benefit. For a neuromuscular disorder a motor function scale has intuitive meaning. Scales that also incorporate relevant pulmonary, cardiac, musculoskeletal and gastrointestinal components add a fuller dimension and capture a more holistic view of the patient. Quality of Life scales address the impact of these various aspects of the disease process on the patient. There are two approaches to designing such a functional scale: (1) utilize a global scale and test it in different disease settings and (2) design a disease-specific scale. For Spinal Muscular Atrophy (SMA), examples of the former are the Gross Motor Function Measure and the Motor Function Measure. Disease-specific scales include the Hammersmith Motor Function Scale and the CHOP INTEND. These scales capture fundamental aspects of neck, trunk and limb motor ability within functionally relevant domains and are age-appropriate. They vary in ease of administration. Each has attractive features and may be useful as an outcome measure for a clinical trial in SMA. Challenges remain, however, to the effective development and implementation of these scales. Harmonization among study groups is critical if these motor function scales are to be adopted widely. Efforts by TREAT-NMD, for example, are working effectively towards this goal.
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