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Optimisation of the Reflux-symptom Association Statistics for Use in Infants Being Investigated by 24-hour pH impedance

Omari, Taher I; Schwarzer, Andrea; vanWijk, Michiel P§; Benninga, Marc A§; McCall, Lisa*; Kritas, Stamatiki*; Koletzko, Sibylle; Davidson, Geoffrey P

Journal of Pediatric Gastroenterology & Nutrition: April 2011 - Volume 52 - Issue 4 - p 408–413
doi: 10.1097/MPG.0b013e3181f474c7
Original Articles: Gastroenterology

Background and Aim: pH-impedance monitoring is used to diagnose symptomatic gastroesophageal reflux (GER) based on symptom association probability (SAP). Current criteria for calculation of SAP are optimised for heartburn in adults. Infants, however, demonstrate a different symptom profile. The aim of the present study was to optimise criteria for calculation of SAP in infants with GER disease.

Patients and Methods: Ten infants referred for investigation of symptomatic reflux were enrolled. GER episodes were recorded using a pH-impedance probe, which remained in place for 48 hours. During the test, cough, crying, and regurgitation were marked. Impedance recordings were analysed for the occurrence of bolus reflux episodes. SAP for behaviors following reflux episodes was separately calculated for day 1 and day 2 using automated reporting software, which enabled the time window used for SAP calculations to be modified from 15 to 600 seconds. Day-to-day agreement of SAP was assessed by calculating the 95% limits of agreement (mean difference ± 1.96 standard deviations of differences) and their confidence intervals.

Results: The number of bolus GER episodes and symptom episodes reported did not differ from day to day. The best agreement in SAP between the 2 days was found using time intervals of 2 minutes for cough, 5 minutes for crying, and 15 seconds and/or 2 to 5 minutes for regurgitation.

Conclusions: We conclude that the standard 2-minute time interval is appropriate for the investigation of cough and regurgitation symptoms. The day-to-day agreement of SAP for crying was poor using standard criteria, and our results suggest increasing the reflux-symptom association time interval to 5 minutes.

*Gastroenterology Unit, Children, Youth, and Women's Health Service, North Adelaide, Australia

School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, Australia

Dr von Haunersches Kinderspital, Ludwig Maximilians University Munich, Munich, Germany

§Department of Paediatric Gastroenterology and Nutrition, Emma Children's Hospital AMC, Amsterdam, The Netherlands.

Received 12 April, 2010

Accepted 21 July, 2010

Address correspondence and reprint requests to Taher Omari, PhD, NH&MRC Senior Research Fellow, Gastroenterology Unit, Child, Youth & Women's Health Service, North Adelaide, Australia (e-mail:

Dr Taher Omari received research funding from Sandhill Scientific. Sandhill Scientific had no role in the conception and preparation of this article. This research project was funded by the Financial Markets Foundation for Children.

Dr Taher Omari is a member of the advisory board for Sandhill Scientific; Prof Sibylle Koletzko is a member of the advisory board of AstraZeneca and received a research grant and honorarium for lectures from Astra/Zeneca; the other authors report no conflicts of interest.

Copyright 2011 by ESPGHAN and NASPGHAN