S.P.4 Functional changes in Duchenne muscular dystrophy: A 24 month longitudinal cohort study

Abstract Six minute walk test (6MWT), timed items and North Star Ambulatory Assessment (NSAA) are increasingly used as possible outcome measures in clinical trials in Duchenne Muscular Dystrophy (DMD). Longitudinal data have previously been reported following changes in their scores over a 12 month period. The aim of the study was to assess 6MWT and NSAA in a cohort of 119 ambulant DMD boys over 24 months in order to establish the spectrum of possible changes over a longer period of time. The study is a longitudinal multicentric cohort study. 119 ambulant DMD patients were assessed using 6MWT, NSAA at baseline 12 and 24 months. Clinical data including age and steroid treatment were collected. During the 24 months of the study, we observed a progressive decline in both measures that was more obvious in the second year. Not all the DMD boys in our cohort showed a decline as young boys showed some improvement in their 6MWT and NSAA scores up to the age of 7. Fifteen patients (12.6%) lost the ability to walk independently: 2/15 by the end of the first year and the other 13 in the second year. Another 22 patients (21.1%) were still able to walk independently but were unable to get up from supine (8/22 at baseline, 4 at 12 months, 10 at 24 months). Four children also lost the ability to perform the 6MWT (2 at 12 months and the other 2 at 24 months). This study provides longitudinal data of NSAA and 6MWT over a 24 month period. These data can be useful when designing a clinical trial.