Tom R Geisbush1, Nicole Visyak2, Lavanya Madabusi2, Seward B Rutkove3, Basil T Darras2. 1. Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. 2. Boston Children's Hospital, Harvard Medical School, Boston, MA, USA. 3. Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. Electronic address: srutkove@bidmc.harvard.edu.
Abstract
OBJECTIVE: High reliability is a prerequisite for any test to be useful as a biomarker in a clinical trial. Here we assessed the reproducibility of electrical impedance myography (EIM) in children by comparing data obtained by different evaluators on separate days. METHODS: Healthy boys and boys with Duchenne muscular dystrophy (DMD) aged 2-14 years underwent EIM of multiple muscles performed by two evaluators on two visits separated by 3-7 days. Single and multifrequency data were analyzed. Reliability was assessed via calculation of the percent relative standard deviation (% RSD), Bland-Altman analysis, and the intraclass correlation coefficient (ICC). RESULTS: For both individual muscle data and data averaged across muscles, intra-evaluator measurements showed high repeatability for both 50 kHz phase and 50/200 kHz phase ratio values, with ICCs generally above 0.90 and % RSD below 10%. Inter-evaluator results showed very similar ICC and % RSD values as those obtained by the same evaluator. CONCLUSIONS: Both the 50 kHz phase and 50/200 kHz phase ratio are reliable measures both across time and evaluators and in both health and disease. SIGNIFICANCE: These results support the concept that EIM can serve as a reliable measure in clinical therapeutic trials in a pediatric population.
OBJECTIVE: High reliability is a prerequisite for any test to be useful as a biomarker in a clinical trial. Here we assessed the reproducibility of electrical impedance myography (EIM) in children by comparing data obtained by different evaluators on separate days. METHODS: Healthy boys and boys with Duchenne muscular dystrophy (DMD) aged 2-14 years underwent EIM of multiple muscles performed by two evaluators on two visits separated by 3-7 days. Single and multifrequency data were analyzed. Reliability was assessed via calculation of the percent relative standard deviation (% RSD), Bland-Altman analysis, and the intraclass correlation coefficient (ICC). RESULTS: For both individual muscle data and data averaged across muscles, intra-evaluator measurements showed high repeatability for both 50 kHz phase and 50/200 kHz phase ratio values, with ICCs generally above 0.90 and % RSD below 10%. Inter-evaluator results showed very similar ICC and % RSD values as those obtained by the same evaluator. CONCLUSIONS: Both the 50 kHz phase and 50/200 kHz phase ratio are reliable measures both across time and evaluators and in both health and disease. SIGNIFICANCE: These results support the concept that EIM can serve as a reliable measure in clinical therapeutic trials in a pediatric population.
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