Background: The Duchenne Video Assessment (DVA) is a home-based tool that measures ease of movement in those with Duchenne muscular dystrophy (DMD) through identification of movement compensations. The DVA directs caregivers to video record patients attempting specific movement tasks using a mobile application. DVA-certified physical therapists rate videos using validated scorecards with clinically meaningful compensatory movement criteria. DVA 2.0 comprises 18 movement tasks and assesses patients at any disease stage through a subset of tasks relevant to their functional group. Prior DVA research focused on task-specific measurement properties while this research focuses on the total composite severity percentage.
Objective: To test the cross-sectional measurement properties of the DVA 2.0 total composite severity percentage using baseline data from the ARISE study.
Methods: ARISE is a longitudinal, observational study of 150 participants with DMD aged 2 and older. We assessed inter-rater reliability (intraclass correlation coefficients (ICCs)) of the total composite severity percentage from 3 raters evaluating 129 participants using two-way random effects models. We evaluated convergent validity by assessing Spearman correlation between DVA 2.0 and North Star Ambulatory Assessment (NSAA) and Performance of Upper Limb (PUL) 2.0. Test-retest DVA data from Baseline and Week 2 were analyzed to estimate expected variability in the total composite severity percentage and to derive the amount of change that exceeds test-retest variability, the minimally detectable difference (MDD).
Results: Inter-rater reliability was excellent for the DVA 2.0 total composite severity percentage (ICC 0.99; 95% confidence interval 0.98, 0.99). DVA 2.0 total composite severity percentage was strongly correlated with NSAA Total Score (ρ =-0.905) and PUL 2.0 Total Score (ρ =-0.928), demonstrating convergent validity. The MDD was 6% for the total composite severity percentage.
Conclusion: The DVA 2.0 composite severity percentage was found to be a valid and reliable measure of ease of movement for individuals with DMD.