Inter-observer agreement for multichannel intraluminal impedance-pH testing

P>Twenty-four-hour ambulatory multichannel intraluminal impedance (MII)-pH detects both acid and nonacid reflux (NAR). A computer-based program (Autoscan (TM), Sandhill Scientific, Highlands Ranch, CO, USA) automates the detection of reflux episodes, increasing the ease of study interpretation. Inter-observer agreement between multiple reviewers and with Autoscan (TM) for the evaluation of significant NAR with MII-pH has not been studied in the adult population. Twenty MII-pH studies on patients taking a proton pump inhibitor twice daily were randomly selected. Autoscan (TM) analyzed all studies using the same pre-programmed parameters. Four reviewers interpreted the MII-pH studies, adding or deleting reflux episodes detected by Autoscan (TM). Positive studies for NAR and total reflux episodes were based on published criteria. Cohen's kappa statistic (kappa) evaluated inter-observer agreement between reviewers and Autoscan (TM) analysis. The average kappa for pathologic NAR between reviewers was 0.57 (0.47-0.70), and between reviewers and Autoscan (TM) was 0.56 (0.4-0.8). When using the total reflux episode number as a marker for pathologic reflux (acid and NAR), the kappa score was 0.72 (0.61-0.89) between reviewers, and 0.74 (0.53-0.9) when evaluating total reflux episodes. Two reviewers agreed more often with each other and with Autoscan (TM) on the number of NAR episodes, while the other two reviewers agreed with each other, but did not agree with either Autoscan (TM) or the first two reviewers. Inter-observer agreement between reviewers and Autoscan (TM) for detecting pathologic NAR is moderate, with reviewers either excluding more of the Autoscan (TM)-defined events or excluding fewer events and therefore agreeing with Autoscan (TM).