Evaluating motor outcome measures and disease impact in Facioscapulohumeral Muscular Dystrophy to support future therapy approvals and real-world evidence generation

Background
Facioscapulohumeral Muscular Dystrophy (FSHD) is a progressive muscle wasting condition, with prevalence of 1:8000 to 1:20000. FSHD causes a heterogeneous pattern of weakness, leading to subsequent disability, with challenges relating to overhead reaching, transferring from lying to sitting, and walking commonly reported, however life expectancy is typically unaffected. Individuals experience impacts on their quality of life and participation, alongside their physical challenges.

There are no approved therapies for FSHD, but there are novel targeted therapies being trialled. Many existing outcome measures have not proven sensitive to change over time, and there is limited understanding of the impact of FSHD on patients and their families. Improving our knowledge in these areas is essential to help facilitate regulatory approvals, and enable real-world evidence generation.

Methods
This project addressed the issues outlined – via a survey of FSHD patients in the UK, to improve our understanding of the impact of the disease on individuals; a comprehensive systematic review of functional outcome measures in FSHD; and two pilot studies - firstly evaluating the utility of strength assessments using a handheld dynamometer, and secondly evaluating the utility of quantitative gait assessments using inertial measurement sensors to augment traditional walking assessments.

Results
Substantial disease burden was reported by survey respondents – with reduced quality of life, and escalating costs with greater lower limb involvement. The Systematic Review found few measures had strong evidence relating to their validity, nor responsiveness to change highlighting several research gaps. The pilot studies of handheld dynamometry, and inertial sensors found these measures demonstrated responsiveness to change, but were not without some potential limitations, which require further evaluation. Further work is underway to further progress the evaluations undertaken in this project.