Addition of Esophageal Impedance Monitoring to pH Monitoring Increases the Yield of Symptom Association Analysis in Patients off PPI Therapy

BACKGROUND: The additional yield of esophageal impedance monitoring in identification of reflux as the cause of reflux symptoms is unknown. OBJECTIVES: To compare the yield of symptom-reflux association analysis of combined esophageal pH-impedance data with the yield of analysis of pH data alone. METHODS: In 60 patients with symptoms of heartburn and regurgitation combined, 24-h pH-impedance monitoring was performed. Acid-suppressive medication was stopped 1 wk in advance. Patients (48) with at least one symptom during the measurement period were selected for further analysis. Patients were instructed to note the time and nature of their symptoms. Eleven types of reflux episodes were defined, based on combinations of magnitude of the pH drop, nadir pH, and nature of the refluxate (gas and liquid) on impedance tracings. Symptom association analysis-symptom index, the symptom sensitivity index, and the symptom association probability (SAP)-was performed for each definition of reflux. RESULTS: The proportion of patients with a positive SAP (> or =95.0%) varied between 62.5% and 77.1%, depending on the definition of reflux episodes. When both pH and impedance parameters were used to identify reflux, a higher proportion of patients had a positive SAP than with pH alone (77.1%vs 66.7%, p < 0.05). Symptom association analysis for acidic and weakly acidic reflux separately did not result in a higher yield than analysis with all reflux episodes pooled, regardless of pH. CONCLUSION: In patients off proton pump inhibitor, the addition of impedance monitoring to esophageal pH monitoring leads to an increase in the proportion of patients in whom an association between reflux episodes and symptoms can be identified.