title: Esophageal intraluminal baseline impedance differentiates gastroesophageal reflux disease from functional heartburn.
abstract: OBJECTIVE
  Mucosal integrity can be assessed in patients with gastroesophageal reflux disease (GERD) by measuring intraluminal baseline impedance (BI). However, it is not clear whether BI is abnormal in patients with functional heartburn (FH), or can be used to distinguish them from patients with GERD. We compared differences in BI between patients with FH vs GERD.
  
  
  METHODS
  We performed a prospective study of 52 patients (16 men; mean age, 55 y; range, 23-78 y) seen at a tertiary university hospital from February 2009 through December 2012. Thirty-five patients had GERD (19 had nonerosive reflux disease [NERD], 16 had erosive reflux disease [ERD]) and 17 had FH. All patients discontinued proton pump inhibitor therapy and then underwent esophagogastroduodenoscopy and multichannel intraluminal impedance and pH monitoring. BI was assessed at 3, 5, 7, 9, 15, and 17 cm proximal to the lower esophageal sphincter in recumbent patients. Biopsy specimens were taken from 3 cm above the gastroesophageal junction; histology analysis was performed to identify and semiquantitatively score (scale, 0-3) dilated intercellular spaces.
  
  
  RESULTS
  Baseline impedance in the distal esophagus was significantly lower in patients with NERD or erosive reflux disease (ERD) than FH (P = .0006). At a cut-off value of less than 2100 Ω, BI measurements identified patients with GERD with 78% sensitivity and 71% specificity, with positive and negative predictive values of 75%. Also in the proximal esophagus, reduced levels of BI levels were found only in patients with ERD. There were negative correlations between level of BI and acid exposure time (r = -0.45; P = .0008), number of acidic reflux episodes (r = -0.45; P = .001), and proximal extent (r = -0.40; P = .004). Biopsy specimens from patients with NERD or ERD had significant increases in dilation of intercellular spaces, compared with those from patients with FH; there was an inverse association between dilated intercellular spaces and BI in the distal esophagus (r = -0.28; P = .06).
  
  
  CONCLUSIONS
  Measurement of BI in the lower esophagus can differentiate patients with ERD or NERD from patients with FH (78% sensitivity and 71% specificity), and therefore should be considered as a diagnostic tool for patients with proton pump inhibitor-refractory reflux. Low levels of BI are associated with increased exposure to acid and dilation of intercellular spaces, indicating that BI is a marker of mucosal integrity.
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany. Electronic address: Arne.Kandulski@med.ovgu.de.
authors.forename: Arne
authors.initials: A
authors.lastname: Kandulski
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weigt
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Carlos
authors.initials: C
authors.lastname: Caro
authors.affiliation: Institute of Pathology, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Doerthe
authors.initials: D
authors.lastname: Jechorek
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany; Medical Laboratory for Clinical Chemistry, Microbiology and Infectious Diseases, Department of Molecular Genetics, Magdeburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wex
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Malfertheiner
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D003937:Diagnosis, Differential; D017097:Electric Impedance; D050782:Esophageal pH Monitoring; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000473:pathology*; D006356:Heartburn / Q000175:diagnosis* / Q000473:pathology*; D006651:Histocytochemistry; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D062606:Tertiary Care Centers; D055815:Young Adult
keywords: Acid-Suppressive Therapy; Diagnosis; Esophageal Mucosa; MII-pH