title: The 6-minute walk test and other clinical endpoints in duchenne muscular dystrophy: reliability, concurrent validity, and minimal clinically important differences from a multicenter study.
abstract: BACKGROUND
  An international clinical trial enrolled 174 ambulatory males ≥5 years old with nonsense mutation Duchenne muscular dystrophy (nmDMD). Pretreatment data provide insight into reliability, concurrent validity, and minimal clinically important differences (MCIDs) of the 6-minute walk test (6MWT) and other endpoints.
  
  
  METHODS
  Screening and baseline evaluations included the 6-minute walk distance (6MWD), timed function tests (TFTs), quantitative strength by myometry, the PedsQL, heart rate-determined energy expenditure index, and other exploratory endpoints.
  
  
  RESULTS
  The 6MWT proved feasible and reliable in a multicenter context. Concurrent validity with other endpoints was excellent. The MCID for 6MWD was 28.5 and 31.7 meters based on 2 statistical distribution methods.
  
  
  CONCLUSIONS
  The ratio of MCID to baseline mean is lower for 6MWD than for other endpoints. The 6MWD is an optimal primary endpoint for Duchenne muscular dystrophy (DMD) clinical trials that are focused therapeutically on preservation of ambulation and slowing of disease progression.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Neuromuscular Medicine and Rehabilitation Research Center, University of California Davis School of Medicine, Davis, California, 95817, USA.
authors.forename: Craig M
authors.initials: CM
authors.lastname: McDonald
authors.forename: Erik K
authors.initials: EK
authors.lastname: Henricson
authors.forename: R Ted
authors.initials: RT
authors.lastname: Abresch
authors.forename: Julaine
authors.initials: J
authors.lastname: Florence
authors.forename: Michelle
authors.initials: M
authors.lastname: Eagle
authors.forename: Eduard
authors.initials: E
authors.lastname: Gappmaier
authors.forename: Allan M
authors.initials: AM
authors.lastname: Glanzman
authors.forename: Robert
authors.initials: R
authors.lastname: Spiegel
authors.forename: Jay
authors.initials: J
authors.lastname: Barth
authors.forename: Gary
authors.initials: G
authors.lastname: Elfring
authors.forename: Allen
authors.initials: A
authors.lastname: Reha
authors.forename: Stuart W
authors.initials: SW
authors.lastname: Peltz
mesh_terms: D018450:Disease Progression; D005080:Exercise Test; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D017063:Outcome Assessment, Health Care; D010069:Oxadiazoles / Q000627:therapeutic use; D015203:Reproducibility of Results; D013997:Time Factors; D016138:Walking / Q000502:physiology*
chemical_list: D010069:Oxadiazoles; C515878:ataluren
keywords: 6-minute walk test; Duchenne muscular dystrophy; PedsQL; ambulation; energy expenditure index; muscular dystrophy; myometry; natural history; timed function test