The Usefulness of Esophageal Baseline Impedance Levels for the Diagnosis of Nonerosive Reflux Disease and the Proper Time for Measurement in Endoscopy-negative Korean Patients With Esophageal or Supraesophageal Symptoms

Background/Aims Low baseline impedance levels (BILs) have been suggested to be evidence of GERD. The aim of this study is to investigate the usefulness of esophageal BILs for the diagnosis of nonerosive reflux disease (NERD) and the proper time for measurement in endoscopy-negative Korean patients with esophageal or supraesophageal symptoms. Methods Endoscopy-negative patients with esophageal or supraesophageal symptoms who underwent esophageal multichannel intraluminal impedance-pH monitoring were included. BILs were measured in the proximal and distal esophagus around 10 minutes before meals, 10 minutes and 30 minutes after meals, 30 minutes before the start of nighttime sleep, and 30 minutes and 60 minutes after the start of nighttime sleep. Results A total of 104 patients were included in the study. Distal and proximal esophageal BILs were decreased after meal ingestion. The BILs of the distal esophagus were significantly lower at all time points in the NERD group, but not in the reflux hypersensitivity (RH) group, compared with the functional group. The area under the receiver operating characteristic curve for the diagnosis of NERD was significant at all time points, but that for the diagnosis of RH was not. The cut-off value of 2375 Omega or 2125 Omega measured around 30 minutes before or 60 minutes after the start of nighttime sleep, respectively, were appropriate for the diagnosis of NERD. Conclusion The BILs of the distal esophagus measured at time points before or after the start of nighttime sleep appear to be useful for the diagnosis of NERD, but not for the diagnosis of RH, in endoscopy-negative Korean patients with esophageal or supraesophageal symptoms.