title: Proficiency of nerve conduction using standard methods and reference values (Cl. NPhys Trial 4).
abstract: BACKGROUND
  The Cl. NPhys Trial 3 showed that attributes of nerve conduction (NC) were without significant intraobserver differences, although there were significant interobserver differences.
  
  
  METHODS
  Trial 4 tested whether use of written instructions and pretrial agreement on techniques and use of standard reference values, diagnostic percentile values, or broader categorization of abnormality could reduce significant interobserver disagreement and improve agreement among clinical neurophysiologists.
  
  
  RESULTS
  The Trial 4 modifications markedly decreased, but did not eliminate, significant interobserver differences of measured attributes of NC. Use of standard reference values and defined percentile values of abnormality decreased interobserver disagreement and improved agreement of judgment of abnormality among evaluators. Therefore, the same clinical neurophysiologist should perform repeat NCs of therapeutic trial patients.
  
  
  CONCLUSIONS
  Differences in interobserver judgment of abnormality decrease with use of common standard reference values and a defined percentile level of abnormality, providing a rationale for their use in therapeutic trials and medical practice.
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota, 55905, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Litchy
authors.forename: James W
authors.initials: JW
authors.lastname: Albers
authors.forename: James
authors.initials: J
authors.lastname: Wolfe
authors.forename: Charles F
authors.initials: CF
authors.lastname: Bolton
authors.forename: Nancy
authors.initials: N
authors.lastname: Walsh
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Klein
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Zafft
authors.forename: James W
authors.initials: JW
authors.lastname: Russell
authors.forename: Melanie
authors.initials: M
authors.lastname: Zwirlein
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Overland
authors.forename: Jenny L
authors.initials: JL
authors.lastname: Davies
authors.forename: Rickey E
authors.initials: RE
authors.lastname: Carter
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Dyck
mesh_terms: D000368:Aged; D003929:Diabetic Neuropathies / Q000175:diagnosis* / Q000503:physiopathology; D004568:Electrodiagnosis / Q000379:methods*; D006801:Humans; D007866:Leg / Q000294:innervation; D009431:Neural Conduction / Q000502:physiology*; D009482:Neurophysiology / Q000379:methods* / Q000592:standards*; D015588:Observer Variation; D012016:Reference Values; D015203:Reproducibility of Results
keywords: multicenter trial; nerve conduction accuracy; nerve conduction proficiency; neuropathy impairment score; reference values