P.5.4 Clinical outcome measures for dysferlinopathy: An exploration of reliability and suitability of novel functional rating scales

Abstract

As part of an international study assessing a wide range of outcome measures in dysferlinopathy a subset was taken from one site (Newcastle, UK) to assess the reliability of several functional measures. The 6 min walk distance (6MWD) and functional timed tests – Timed Up & Go (TUG), 10 m run/walk, timed four stair climb and descend, timed rise from floor and a motor performance measure adapted for use in dysferlinopathy, the Northstar Ambulatory Assessment for Dysferlinopathy (NSAA for dysferlinopathy). Data on 24 individuals were examined for the above items on two time points, screen and baseline assessment. Individuals were aged between 20–65 years of age. Male to female = 16:16. Ambulant: non-ambulant = 16:8. The maximum time difference between the two assessments was less than 8 weeks in all but four individuals due to MRI unavailability. Times, distances and grades were compared and an exploratory Rasch analysis was conducted on 35 (screen and baseline +3 seen once) NSAA assessments to examine the item fit, person fit, ordering of categories for each item, targeting and reliability (PSI). Results showed good reliability between the two time points for the timed tests and 6MWD. The exploratory Rasch analysis showed the NSAA worked reasonably well in measuring ambulatory motor performance in dysferlinopathy however analysis needs to be repeated on a larger cohort to confirm the findings. Alteration in the items and their scoring scheme would benefit the measurement capabilities of the scale making it more robust for use in clinical trials. We would like to acknowledge the support of the Jain Foundation in this project.