Use of 24-hour oesophageal pH-metry for the detection of gastro-oesophageal reflux in infants: what is the ideal score and the optimal threshold? A receiver-operating-characteristic analysis.

BACKGROUND: The search for the ideal score and best cut-off value to interpret the data from 24-hour continuous pH-monitoring interests both gastroenterologists with adult patients and paediatric gastroenterologists. AIMS: To evaluate 24-hour continuous pH monitoring as a discriminatory test in the diagnosis of gastro-oesophageal reflux disease in a paediatric population, using various pH-metry scores and cut-off values. PATIENTS: One hundred and one patients presenting gastro-oesophageal reflux disease (endoscopic diagnosis of oesophagitis or coincidence between apnoea and reflux episodes observed during pH-metry), median age 10 months, were studied, together with a control group of 84 subjects, median age 11 months. RESULTS: After plotting the receiver operating characteristic curves and calculating the area below them, the evaluation of the total percentage reflux time proved to have a higher capacity for distinguishing between the patients and controls than the Euler score (p < 0.05). The cut-off value of 5.2% for the total percentage reflux time had a sensitivity of 75% and was 88% specific. Using higher cut-off values according to age, a 95% specificity and a 49% sensitivity were obtained. The most sensitive score was the Jolley score: 96% with a cut-off of 64 and 90% with a cut-off of 100 (a value determining the maximum diagnostic accuracy); specificity, however, was low: 39-61%. In addition, the Jolley score was the most useful parameter in detecting patients with apnoeic episodes secondary to gastro-oesophageal reflux disease and allowed a correct diagnosis in 12/13 cases. CONCLUSIONS: a) The simple determination of total percentage reflux time, according to the methodology used, has a higher predictive capacity than the more complex pH-monitoring scores; b) the best cut-off value for total percentage reflux time is 5.2% as it combines a good specificity and sensitivity which are necessary for this test; c) age-dependent cut-off values are highly specific but sensitivity is much too low; d) the Jolley score is very sensitive and this was maintained even when the cut-off was raised to a value of 100; it is the best predictive score for episodes of gastro-oesophageal reflux-dependent apparent life-threatening events.