Gastroesophageal reflux disease in children: how reliable is the gold standard?

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).