title: Gastroesophageal reflux disease in children: how reliable is the gold standard?
abstract: OBJECTIVE
  To investigate the causes and degree of interobserver variability in esophageal pH monitoring for the diagnosis of gastroesophageal reflux.
  
  
  METHODS
  This retrospective study included all children (n = 72) who underwent pH monitoring during 1 year at Maxima Medical Centre in Veldhoven, the Netherlands.
  
  
  RESULTS
  An interobserver variability of 18% was found. Variability was caused by differences in opinion about the duration of registration, doubts about probe position, artifacts and drift of baseline pH.
  
  
  CONCLUSIONS
  Most of these problems can be eliminated by posttest calibration and assessment of the pH electrode position. However, a clear definition of monitoring artifacts is lacking. This study shows that mutual agreement in the interpretation of pH studies was fair (kappa coefficient of 0.70).
authors.affiliation: Department of Pediatrics, University Medical Centre St. Radboud, Nijmegen, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: van Os
authors.forename: J
authors.initials: J
authors.lastname: De Schryver
authors.forename: R H J
authors.initials: RH
authors.lastname: Houwen
authors.forename: W E Tjon A
authors.initials: WE
authors.lastname: Ten
mesh_terms: D002138:Calibration / Q000592:standards; D004567:Electrodes, Implanted / Q000592:standards; D050782:Esophageal pH Monitoring / Q000706:statistics & numerical data*; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D008297:Male; D015588:Observer Variation; D012189:Retrospective Studies