title: Inter-session reliability of electrical impedance myography in children in a clinical trial setting.
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.
  
  
  CONCLUSIONS
  These results support the concept that EIM can serve as a reliable measure in clinical therapeutic trials in a pediatric population.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Tom R
authors.initials: TR
authors.lastname: Geisbush
authors.affiliation: Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Visyak
authors.affiliation: Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Lavanya
authors.initials: L
authors.lastname: Madabusi
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. Electronic address: srutkove@bidmc.harvard.edu.
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
authors.affiliation: Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Basil T
authors.initials: BT
authors.lastname: Darras
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D017097:Electric Impedance; D004576:Electromyography / Q000379:methods / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis* / Q000503:physiopathology*; D009213:Myography / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results
keywords: Duchenne muscular dystrophy; Electrical impedance myography; Reliability measures