Validity and Reliability of the Neuromuscular Gross Motor Outcome.

BACKGROUND: Approved treatments in spinal muscular atrophy (SMA) have resulted in unprecedented gains for many individuals. Use of available outcomes, typically developed for a specific type of SMA, do not cover the range of progression, often resulting in a battery of functional testing being completed at visits. Our objective was to validate the Neuromuscular Gross Motor Outcome (GRO) as a tool to quantify function in SMA across the span of abilities. METHODS: Patients with genetically confirmed SMA completed functional testing at each visit including the Neuromuscular GRO and other appropriate gross motor outcomes. RESULTS: We enrolled 91 patients with SMA types 1 to 3 between 8 days and 32.1 years. The GRO utilizes a 0- to 2-point scale with scores in our cohort ranging from 1 to 95 points with no floor or ceiling effect. GRO scores were significantly different across functional categories (P < 0.001) and treatment status (P = 0.01) and correlated to other functional assessments (P ≤ 0.001). All patients were measured using the GRO, whereas traditional outcomes were only appropriate on 36% to 59% of our cohort. CONCLUSION: The Neuromuscular GRO quantifies function across the span of age and abilities included in our cohort, allowing for continuous longitudinal monitoring on one scale to reduce the burden of testing in our heterogeneous clinic population.

Natural History of Steroid-Treated Young Boys With Duchenne Muscular Dystrophy Using the NSAA, 100m, and Timed Functional Tests.

INTRODUCTION: Clinical trials targeting younger cohorts of boys with Duchenne muscular dystrophy are necessary as earlier intervention may maximize treatment effect. Boys with Duchenne muscular dystrophy often have gross motor delays very early in life, and although they gain skills, they are on a lower trajectory than typical peers. Quantifying the natural rate of motor maturation in Duchenne muscular dystrophy from an early age permits identification of deviations from the expected trajectory related to treatment effects. METHODS: The purpose of our study was to define the natural history in boys aged from ≥3 to <8 years using the North Star Ambulatory Assessment (NSAA), 100-meter timed test (100m), 10-meter walk/run (10m), time to rise (Rise), and 4-stair climb (4SC). Assessments were completed as standard of care during regularly scheduled clinic visits. RESULTS: One hundred sixty-two boys with DMD aged 3.1 to 7.9 years on glucocorticoids were evaluated using one or more of the following tests as appropriate for age: NSAA (N = 158; 3.1-7.9 years), 100m (N = 131; 3.4-7.9 years), 10m (N = 162; 3.1-7.9 years), Rise (N = 160; 3.1-7.9 years), and 4SC (N = 153; 3.1-7.9 years). Longitudinal data are presented by age in a subcohort (N = 64). CONCLUSIONS: Our study documents the baseline function of boys with DMD who are being treated with corticosteroids. These data will be useful to compare ongoing and future therapeutic intervention(s) for DMD.