Facioscapulohumeral muscular dystrophy (FSHD) is a slowly progressive disease, and sensitive endpoints are needed to detect functional changes during clinical trials. Wearable digital health technology (DHT) could provide objective, reliable, and sensitive measures of patients’ functional capabilities in daily life. The European Medicines Agency approved SV95C (stride velocity 95th centile) as a measure of top ambulatory speed derived from the Syde DHT as a primary endpoint for Duchenne muscular dystrophy, where it showed a greater sensitivity to detect change than existing endpoints. This study aims to analytically validate this DHT performance in reconstructing upper and lower limb movements in FSHD from a controlled environment protocol (part 1), and assess the feasibility, minimal and optimal wearing durations, reliability, and external validity of digital measures on data collected during 6 weeks in patients’ daily life (part 2).
The controlled environment study enrolled 17 patients with FHSD and confirmed the excellent precision of the DHT: 98% of strides were detected by the algorithm, and the mean difference between the DHT and the motion capture reference on stride length, velocity and vertical amplitude of upper limb movement were 0.6 cm, 0.5 cm/s, and -0.9 cm, respectively.
The study in patients’ daily life is ongoing. To date, 15 participants with genetically diagnosed FSHD were included: median age 58 years (range 29-69), 40% female, 4 used a walking aid in their daily life. FSHD-specific outcome measures (RICCI-scale and FSHD-COM) were performed at inclusion to assess disease severity. Participants are asked to wear one sensor on each ankle and one sensor on each wrist daily for 6 weeks.
Data on feasibility, reliability and external validity of digital measures of lower limb activity will be presented at the congress. Future work will assess the metric properties of digital measures of upper limb activity in the same patients, as well as develop digital variables specific for FSHD.