Related Experiment Video
Updated: May 9, 2026
Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy
Published on: January 12, 2019
Rasch analysis of clinical outcome measures in spinal muscular atrophy
Stefan J Cano1, Anna Mayhew, Allan M Glanzman
1Clinical Neurology Research Group, Room N13 ITTC Building, Peninsula College of Medicine and Dentistry, Tamar Science Park, Plymouth, United Kingdom.
Introduction:
Trial design for SMA depends on meaningful rating scales to assess outcomes. In this study Rasch methodology was applied to 9 motor scales in spinal muscular atrophy (SMA).
Methods:
Data from all 3 SMA types were provided by research groups for 9 commonly used scales. Rasch methodology assessed the ordering of response option thresholds, tests of fit, spread of item locations, residual correlations, and person separation index.
Results:
Each scale had good reliability. However, several issues impacting scale validity were identified, including the extent that items defined clinically meaningful constructs and how well each scale measured performance across the SMA spectrum.
Conclusions:
The sensitivity and potential utility of each SMA scale as outcome measures for trials could be improved by establishing clear definitions of what is measured, reconsidering items that misfit and items whose response categories have reversed thresholds, and adding new items at the extremes of scale ranges.
