The Sensitivity of Multichannel Intraluminal Impedance and the pH Probe in the Evaluation of Gastroesophageal Reflux in Children

Background & Aims: Multichannel intraluminal impedance (MII) has been incorporated into gastroesophageal reflux evaluations in children despite a lack of evidence comparing it to the gold standard pH probe. The aim of this study was to compare these two technologies. Methods: Twenty-five consecutive, untreated children undergoing pH-MII recording were studied. Sensitivities for the pH probe and MII were defined as: (acid+pH-only episodes)/(acid+non-acid+pH-only episodes) and (acid+non-acid episodes)/(acid+non-acid+pH-only episodes), respectively. Sensitivities were compared using paired t testing. After the analysis was performed, the pH-MII tracings of 25 age-matched children taking acid suppression therapy were compared and sensitivity calculations were performed. Results: In untreated patients, 1845 reflux episodes were detected, and 1702 were detected in treated patients. The mean sensitivities of pH probe and MII in untreated patients were 80.6 ± 18.2% and 76.1 ± 13.5%, respectively (P = .41). The mean sensitivities of pH probe and MII in treated patients were 47.2 ± 36.0% and 80.3 ± 21.1%, respectively (P = .005). Twenty-five percent of reflux episodes were pH-only episodes. There were no differences in the mean number of acid or non-acid reflux episodes in patients with normal and abnormal pH probe studies. Instead, there were significantly more pH-only episodes in patients with abnormal probe studies. Conclusions: The sensitivity of MII equals that of the pH probe in untreated patients but is superior to the pH probe in treated patients. pH-only episodes are numerous in pediatrics and should be included in pH-MII analyses.