title: Addition of esophageal impedance monitoring to pH monitoring increases the yield of symptom association analysis in patients off PPI therapy.
abstract: BACKGROUND
  The additional yield of esophageal impedance monitoring in identification of reflux as the cause of reflux symptoms is unknown.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Gastroenterology, St. Antonius Hospital, PO Box 2500, 3430 EM Nieuwegein, The Netherlands.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Bredenoord
authors.forename: Bas L A M
authors.initials: BL
authors.lastname: Weusten
authors.forename: Robin
authors.initials: R
authors.lastname: Timmer
authors.forename: José M
authors.initials: JM
authors.lastname: Conchillo
authors.forename: André J P M
authors.initials: AJ
authors.lastname: Smout
mesh_terms: D000328:Adult; D000368:Aged; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D003201:Computers; D003625:Data Collection / Q000295:instrumentation; D005260:Female; D005745:Gastric Acidity Determination / Q000295:instrumentation*; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D010992:Plethysmography, Impedance / Q000295:instrumentation*; D019518:Postprandial Period; D011237:Predictive Value of Tests; D054328:Proton Pump Inhibitors; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation
chemical_list: D000897:Anti-Ulcer Agents; D054328:Proton Pump Inhibitors