Objective: We previously reported the feasibility of remote study of function and disease severity in people with myotonic dystrophy type 1 (DM1). Here, we assess the test-retest reliability of remote assessment of strength and function.
Methodology: Subjects were identified through the National Registry and enrolled remotely. Participants received a toolkit including a tripod, a tablet equipped with software (Zoom for videoconferencing), and devices for assessments of strength and function. Two consecutive remote study visits (RSV) were conducted within 3 months. At both RSVs, grip, pinch, and tongue strength, forced vital capacity (FVC, sitting and supine), sniff negative inspiratory pressure (SNIP), 9-hole-peg-test, video-hand-opening-time, and timed-up-and-go (TUG) were determined under video supervision. The 10-meter-walk/run-test (10MWRT) was performed, safety and space permitting. Functional assessments were video-recorded for offline analysis. Intraclass correlation coefficients (ICC) were calculated using a 2-way random effects model to evaluate the agreement between repeated measurements. ICCs were defined as excellent (>0.9), good (0.75-0.9), or moderate (0.5-0.75). Bland Altman Plots were generated to evaluate systemic bias.
Results: Forty individuals with DM1 (20-83 years of age) participated in 2 consecutive RSVs. RSVs were, on average, 26 days (range 4-69 days) apart. No falls or injuries occurred. Quantitative assessments were completed in >90% of the visits, except for 10MWT (82.5% of the visits). The ICC showed excellent reliability for sitting and supine FVC, handgrip, and pinch testing. SNIP, tongue, and buccal strength testing showed moderate to excellent reliability. Analysis of test-retest reliability of the 9-hole-peg-test, video-hand-opening-time, TUG, and 10MWRT are in progress and will be presented.
Conclusions: This data further demonstrates the feasibility of remote study of DM1 disease severity. Test-retest reliability of remote assessments of strength and function is acceptable. This data supports this novel platform to study large cohorts, enabling broad participation while reducing the burden on individuals and families.