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. 2024;11(1):153-166.
doi: 10.3233/JND-230159.

Quantifying Variability in Motor Function in Duchenne Muscular Dystrophy: UK Centiles for the NorthStar Ambulatory Assessment, 10 m Walk Run Velocity and Rise from Floor Velocity in GC Treated Boys

Georgia Stimpson  1 , Deborah Ridout  2 , Amy Wolfe  1   3 , Evelin Milev  1   3 , Emer O'Reilly  1   3 , Adnan Manzur  1 , Anna Sarkozy  1 , Francesco Muntoni  1   3 , Tim J Cole  2 , Giovanni Baranello  1   3 ; NorthStar Network
Affiliations

Quantifying Variability in Motor Function in Duchenne Muscular Dystrophy: UK Centiles for the NorthStar Ambulatory Assessment, 10 m Walk Run Velocity and Rise from Floor Velocity in GC Treated Boys

Georgia Stimpson et al. J Neuromuscul Dis. 2024.

Abstract

Background Boys with Duchenne Muscular Dystrophy (DMD) display heterogeneous motor function trajectory in clinics, which represents a significant obstacle to monitoring.

Objective: In this paper, we present the UK centiles for the North Star Ambulatory Assessment (NSAA), the 10 m walk/run time (10MWR) and velocity (10MWRV), and the rise from floor time (RFF) and velocity (RFFV) created from a cohort of glucocorticoid treated DMD boys between the age of 5 and 16 years.

Methods: Participants were included from the UK NorthStar registry if they had initiated steroids (primarily deflazacorts/prednisolone, intermittent/daily) and were not enrolled in an interventional trial. Assessments were included if the participant had a complete NSAA, the timed tests had been completed or the corresponding items were 0, or the participant was recorded as non-ambulant, in which case the NSAA was assumed 0.

Results: We analysed 3987 assessments of the NSAA collected from 826 participants. Of these, 1080, 1849 and 1199 were imputed as 0 for the NSAA, RFFV and 10MWRV respectively. The 10th, 25th, 50th, 75th and 90th centiles were presented. The NSAA centiles showed a peak score of 14, 20, 26, 30 and 32 respectively, with loss of ambulation at 10.7, 12.2 and 14.3 years for the 25th, 50th and 75th centiles, respectively. The centiles showed loss of rise from floor at 8.6, 10.1 and 11.9 years and a loss of 10MWR of 0 at 8.9, 10.3 and 13.8 years for the 25th, 50th and 75th centiles, respectively. The centiles were pairwise less correlated than the raw scores, suggesting an increased ability to detect variability in the DMD cohort.

Conclusions: The NSAA, 10MWR and RFF centiles may provide insights for clinical monitoring of DMD boys, particularly in late ambulatory participants who are uniformly declining. Future work will validate the centiles in national and international natural history cohorts.

Keywords: 10 meter walk/run; Duchenne muscular dystrophy; NorthStar ambulatory assessment; centiles; glucocorticoids; rise from floor.

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Conflict of interest statement

FM reports participation to Scientific Advisory boards and teaching initiatives for Novartis, Biogen, Roche; he is involved as an investigator in clinical trials from Novartis, Biogen, and Roche. Both institutions (UCL and GOSH) receive funding from Biogen and Roche for the SMAREACH SMA registry. GB is PI of clinical trials by Pfizer, NS Pharma, and Reveragen, and has received speaker and/or consulting fees from Sarepta, PTC Therapeutics, Biogen, Novartis Gene Therapies, Inc. (AveXis), and Roche and has worked as principal investigator of SMA studies sponsored by Novartis Gene Therapies, Inc., and Roche. GS, DR, AW, EM, EOR, AM, AS and TS have no conflict of interest to declare.

Figures

Fig. 1
Fig. 1
Data diagram.
Fig. 2
Fig. 2
Imputation of score 0 by age for the three outcome measures.
Fig. 3
Fig. 3
Relative rates of score 0 on Rise from Floor Velocity, 10m Walk Run Velocity and NSAA.
Fig. 4
Fig. 4
NSAA centiles for age.
Fig. 5
Fig. 5
Understanding the NSAA using centiles.
Fig. 6
Fig. 6
Rise from floor velocity centiles for age.
Fig. 7
Fig. 7
10m Walk run velocity centiles for age.
See this image and copyright information in PMC

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