title: Pulse wave velocity measurements are reproducible in multiple trained observers: a short report.
abstract: BACKGROUND
  Arterial stiffness, measured by pulse wave velocity (PWV), is highly predictive of mortality in dialysis patients. As such, PWV is frequently used in clinical research studies and may have a role in clinical practice if shown to be suitably reliable. Measurement of PWV using the SphygmoCor system is known to be an observer-dependent technique. The aim of this study was to investigate the ability of 4 observers to acquire reproducible PWV and pulse wave analysis (PWA) measurements after a 6-week training period.
  
  
  METHODS
  Reproducibility of this technique was investigated using repeated measurements of the carotid-femoral PWV and PWA of the radial pulse by the 4 observers after a period of training. Both healthy volunteers and individuals with chronic kidney disease (CKD) were recruited for this study. Measurements were considered to have met quality control if 2 consecutive measurements were visually acceptable, within 1.5 m/s of each other and had a standard deviation of less than 10%. A fixed-effect analysis of variance was used to test the variation in measurements between the observers; the intraclass correlation coefficient (ICC) was used to assess the statistical agreement between the observers.
  
  
  RESULTS
  A total of 20 individuals volunteered for PWV and PWA measurements (13 with CKD and 7 without); the mean age was 58 years (range 24-83). The average PWV was 9.4 +/- 3.6 m/s. There was no significant difference shown between the 4 observers' measurements (p = 0.25). Further, there was good statistical agreement between the observers (ICC = 0.95).
  
  
  CONCLUSIONS
  After a period of training it is possible for multiple observers to have reproducible measurements of PWV and PWA. Assurance of reproducibility is important when more than one individual is collecting data in a study, particularly when assessing changes over time.
authors.affiliation: St. Paul's Hospital, Vancouver, B.C., Canada. msigrist@providencehealth.bc.ca
authors.forename: M K
authors.initials: MK
authors.lastname: Sigrist
authors.forename: G
authors.initials: G
authors.lastname: Chiarelli
authors.forename: A
authors.initials: A
authors.lastname: Levin
authors.forename: A
authors.initials: A
authors.lastname: Romann
authors.forename: C
authors.initials: C
authors.lastname: Weber
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000592:standards; D015924:Blood Pressure Monitors / Q000592:standards*; D002318:Cardiovascular Diseases / Q000503:physiopathology / Q000517:prevention & control; D005260:Female; D006282:Health Personnel / Q000193:education*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011673:Pulsatile Flow / Q000502:physiology*; D006435:Renal Dialysis / Q000009:adverse effects*; D051436:Renal Insufficiency, Chronic / Q000503:physiopathology* / Q000628:therapy; D015203:Reproducibility of Results; D055815:Young Adult