Comparison of strength testing modalities in dysferlinopathy.

Area of Science:

• Neuromuscular Disorders
• Clinical Outcome Measurement
• Biomedical Engineering

Background:

• Dysferlinopathy presents with variable muscle weakness and progression rates.
• Changes in muscle strength impact functional abilities in patients.
• Standardized strength testing is crucial for tracking disease progression and treatment efficacy.

Purpose of the Study:

• To compare the sensitivity of three strength testing methods in dysferlinopathy.
• To identify the most responsive muscle groups for outcome assessment.
• To inform the selection of optimal strength testing for clinical trials.

Main Methods:

• Evaluated patients using functional scales, manual muscle testing, and handheld dynamometry (HHD).
• Utilized a fixed-frame system (Fixed) at select sites.
• Analyzed 1-year data for reliability and sensitivity to change.

Main Results:

• Both HHD and Fixed systems detected significant changes in summed muscle strength over 12 months.
• Strength measures strongly correlated with functional scales (rho = 0.68–0.92).
• Individual muscle group variability was noted across visits.

Conclusions:

• HHD and Fixed systems are sensitive to changes in dysferlinopathy over 12 months.
• HHD is a cost-effective and easily implementable option.
• Researchers should consider strength testing variability and prioritize functional measures with lower variability for clinical trial endpoints.