Analysis of the natural evolution of SV95C in ambulant patients with Duchenne muscular dystrophy

The progressive nature of functional loss in Duchenne Muscular Dystrophy (DMD) is well established and routinely characterised in clinic using assessments such as the North Star Ambulatory Assessment and the Six Meter Walk Test. The trajectory of functional loss depends on the patient's age and baseline functional ability. There is a need to better characterise the trajectory of disease progression in order to try to predict disease evolution and optimise patient care. Stride Velocity at the 95th Centile (SV95C) is a novel clinical outcome measure that is captured during normal daily living using wearable technology and represents the maximum ambulatory ability of a patient. SV95C is qualified by the European Medicines agency (EMA) for use as a secondary endpoint in pivotal studies in DMD and is an important real-world functional endpoint complementing the traditional in-clinic assessments. SV95C declines by approximately 7% per year in ambulant patients with DMD who are on a stable dose of steroids. In other functional endpoints such as the NSAA and 6MWT the decline is dependent on the patient's age and baseline ambulatory abilities. This study aims to investigate how yearly change of SV95C is also dependent upon age and baseline function. We will analyse how the evolution of SV95C can be predicted by the baseline value of SV95C and age, using non-linear and linear multiparametric regression models. This analysis will be conducted on data from ActiLiège-NEXT, a prospective natural history study in ambulant patients with DMD. This study was designed to characterise longitudinal functional disease progression using multiple outcome measures, including SV95C. It includes patients with DMD between 4 and 20 years old studied over 1 year. SV95C was measured daily using ActiMyo®, a class I CE medical device with two sensors worn on the ankles. These data will advance our understanding of the importance of SV95C as an outcome measure for functional disease progression in DMD.