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

Abstract

Background/AimsSymptom 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. MethodsForty 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). ResultsIntra-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. ConclusionsIntra-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.

Modern diagnosis of GERD: the Lyon Consensus

“… 61 However, ‘rapid’ visual analysis limited to the 2 min window preceding each symptom event yields SI and SAP values concordant with a full visual analysis, with excellent intraobserver and interobserver agreement. 79 Although pH-impedance monitoring provides analysis of symptom-reflux association on PPI therapy, testing off PPI therapy increases the number of symptoms reported, which increases the chance of a positive symptom-reflux association. 80 …”

Ambulatory reflux monitoring for diagnosis of gastro‐esophageal reflux disease: Update of the Porto consensus and recommendations from an international consensus group

“…As a consequence, calculation of Symptom Index (SI) and Symptom Association Probability (SAP) might be affected . A manual review of the 2 minutes preceding each symptom event in pH impedance studies may classify most of the patients similarly as manual analysis of the 24‐hours study regarding the positivity of SI and SAP . Therefore, manual editing of the 2 minutes preceding each symptom event is recommended ( GRADE very low ).…”

Normal values and regional differences in oesophageal impedance-pH metrics: a consensus analysis of impedance-pH studies from around the world

“…Although normal values are available for commonly used impedance-pH parameters [3][4][5][6][7][8][9][10][11] , their global application has limitations, stemming from use of small healthy volunteer cohorts from one or two countries for normative data. Further, significant technical limitations in analysis exist, such as inclusion of pH drops from meals/artefacts and inconsistent rules for identification of impedance reflux events, leading to large inter-reviewer variability 10,[12][13][14][15][16][17][18] . Several measurement systems are utilized for impedance-pH monitoring worldwide.…”