Supplement Abstracts Submitted for the 73rd Annual Scientific Meeting of the American College of Gastroenterology: ESOPHAGUS
Purpose: Whether it is conventional 24 hr pH testing or combined impedance-pH technology, ambulatory reflux monitoring is a major tool used to diagnose GERD. Perhaps as important as diagnosing reflux is determining whether or not it is related to symptoms. The symptom index (SI) and symptom association probability (SAP) are two main parameters that are used to establish symptom association with reflux, and there is much debate over which parameter is more sensitive and specific. The aim of this study was to determine if there is agreement among experts in evaluating symptoms during ambulatory reflux monitoring and in establishing symptom association with GERD.
Methods: Twenty-one leading worldwide authorities in esophageal diseases were asked to answer a questionnaire regarding reflux monitoring. All experts were asked which commercial software they use for analysis and how mealtimes and cluster of symptoms were evaluated, but the remainder of questions differed depending on use of SI or SAP as the main parameter for establishing symptom association with reflux.
Results: Seventeen experts (81%) responded to the questionnaire. Nine of them chose the SI as their diagnostic parameter, and 8 preferred the SAP. Of those who chose the SI, all 9 use the same formula (# symptom events preceded by reflux/number of symptom events), calculated manually; 7/9 use a 5-minute time interval for establishing a positive correlation, and 2/9 use a 2-minute window. There is variability among the number of symptom events used in the denominator for the SI: 2/9 include symptom events during meals, 8/9 count a cluster of symptom events within two minutes of each other as one symptom event, and 4/9 always include symptom events that occur after meals even if there is not a two or five minute “meal-free” analysis time. There were no two experts who agreed on all answers. Of those who chose the SAP, all 8 allow the software to calculate the value, and 4/8 do not know the formula used by the software. There is variability among the total number of symptom events included in the SAP: 2/8 include symptom events during meals, 7/8 count a cluster of symptom events within two minutes of each other as one symptom event, and 1/8 counts a cluster of symptom events within thirty seconds of each other as one symptom event. There were no two experts who agreed on all answers.
Conclusion: With the exception of grouping a cluster of symptom events, there is no consensus among worldwide GERD experts in determining the association between reflux and symptoms. In addition, the SI or SAP value is not necessarily the same in laboratories around the world.