Responsiveness of outcome measures in myotonic dystrophy type 1

• Main Authors: Kirsten L. Knak, Aisha M. Sheikh, Nanna Witting, John Vissing
• Format: Article
• Language: English
• Published: Wiley 2020-08-01
• Series: Annals of Clinical and Translational Neurology
• Online Access: https://doi.org/10.1002/acn3.51129

Abstract Objective As myotonic dystrophy type 1(DM1) evolves slowly and interventional trials often have a short duration, responsive outcomes in DM1 are needed. The objective of this study was to determine the responsiveness of muscle strength, balance, and functional mobility measurements after a 1‐year follow‐up period in individuals with DM1. Methods Sixty‐three adults with noncongenital DM1 completed the following assessments at baseline and at 1‐year follow‐up: Handheld dynamometry (lower limbs), stationary dynamometry (lower limbs), step test, timed‐up‐and‐go test (TUG), modified clinical test of sensory integration and balance (mCTSIB), feet‐together stance, tandem stance, one‐leg stance, 10‐meter walk test, and sit‐to‐stand test. Results Change was captured by stationary dynamometry (proximal flexor and extensor muscles), handheld dynamometry (proximal flexor and distal extensor muscles), TUG, and mCTSIB (P ≤ 0.04). Ceiling or floor effects were shown for most static balance tests. Interpretation Overall, adequate responsiveness was shown for both muscle strength dynamometers, TUG and mCTSIB. These outcomes are therefore likely candidate endpoints for clinical trials lasting 1 year. Most static balance tests are not responsive and not recommended in a heterogeneous DM1 population.