365P Duchenne video assessment 2.0 scorecard performance: evaluation of inter-item and inter-scorecard relationships

Abstract

People with Duchenne muscular dystrophy (DMD) compensate for muscle weakness by changing their movement patterns. The Duchenne Video Assessment (DVA) is a home-based tool that measures ease of movement through identification of movement compensations. The DVA directs caregivers to video record patients attempting specific movement tasks (e.g., Climb 5 Stairs) at home using a mobile application. DVA 2.0 comprises 18 movement tasks and assesses patients at any disease stage through a subset of tasks relevant to their functional group. DVA-certified physical therapists rate the videos using validated scorecards with clinically meaningful compensatory movement criteria (“items”). ARISE is a longitudinal, observational study of 150 participants with DMD aged 2 and older to evaluate the measurement properties of DVA 2.0 over 24 months. Using baseline data, we evaluated the relationships among DVA 2.0 scorecards and criteria to confirm that they contribute distinct information to the outcome. We assessed the correlation between each criteria pair, and correlation type (polychoric, rank-biserial, Phi) was determined by number of levels within compared criteria. We assessed inter-scorecard relationships using a Spearman correlation matrix. Criteria and scorecards with very strong correlations (>|0.9|) were explored for content overlap and considered for removal. All scorecards and all but one pair of criteria had correlations below the threshold. One pair of criteria for Reach Across the Table to Grab a Cell Phone was above the threshold (rpc = 0.971), but 15% of the study population differed in severity level for the two criteria. Since expert consensus previously established the clinical meaningfulness of each criterion and maintaining both criteria provides additional information for 15% of the study population, both were retained. The results confirm that all DVA 2.0 criteria and scorecards contribute distinct information about the ease of movement of people with DMD.