Impedance pH Monitoring: Intra-observer and Inter-observer Agreement and Usefulness of a Rapid Analysis of Symptom Reflux Association

BACKGROUND/AIMS: Symptom reflux association analysis is especially helpful for evaluation and management of proton pump inhibitor (PPI) refractory patients. An accurate calculation requires manual editing of 24-hour multichannel intraluminal impedance-pH (MII-pH) tracings after automatic analysis. Intra- and inter-observer agreement as well as reliability of rapid editing confined to the time around symptomatic episodes are unknown. Aim of this study was to explore these topics in a prospective multicenter study. METHODS: Forty consecutive patients who were off PPI therapy underwent MII-pH recordings. After automatic analysis, their tracings were anonymized and randomized. Three experienced observers, each one trained in a different European center, independently performed manual editing of 24-hour tracings on 2 separate occasions. Values of symptom index and symptom association probability for acid and non acid reflux were transformed into binary response (i.e., positive or negative). RESULTS: Intra-observer agreement on symptom reflux association was 92.5% to 100.0% for acid and 85.0% to 97.5% for non-acid reflux. Inter-observer agreement was 100.0% for acid and 82.5% to 95.0% for non-acid reflux. Values for symptom index and symptom association probability were similar. Concordance between 24-hour and rapid (2 minutes-window before each symptomatic episode) editings for symptom reflux association occured in 39 to 40 patients (acid) and in 37 to 40 (non-acid), depending on the observer. CONCLUSIONS: Intra- and inter-observer agreement in classifying patients with or without symptom reflux association at manual editing of 24-hour tracings was high, especially for acid reflux. Classifying patients according to a rapid editing showed excellent concordance with the 24-hour one and can be adopted in clinical practice.