title: Usefulness of baseline impedance in patients with proton pump inhibitor-refractory nonerosive reflux disease.
abstract: OBJECTIVE
  Approximately more than half of patients with non-erosive reflux disease (NERD) do not respond to proton pump inhibitor (PPI) therapy. Although NERD is a heterogeneous entity, previous study showed that multichannel intraluminal impedance (MII)-pH monitoring could distinguish reflux-related disease from PPI-refractory NERD. The aim of this study was to examine the usefulness of baseline impedance in PPI-refractory NERD patients.
  
  
  METHODS
  We used MII-pH monitoring to analyze reflux parameters, symptom index (SI), and baseline impedance in 37 PPI-refractory NERD patients on PPI. Reflux was divided into acid (nadir pH ≤ 4) and non-acid (nadir pH > 4). Subjects were classified as having reflux-related disease based on abnormal reflux parameters or positive SI (≥ 50%), or non-reflux-related disease, including functional heartburn, based on negative SI with normal reflux parameters.
  
  
  RESULTS
  A total of 26 of the 37 subjects were diagnosed with reflux-related disease, including eight with acid-reflux type and 18 with non-acid-reflux type, and nine with functional heartburn and two with pseudohypersalivation. There were no significant differences in the clinical characteristics of the acid-reflux type, non-acid-reflux type, and functional heartburn groups. The baseline impedance value in the acid-reflux type (1245 ± 392 Ω) was significantly lower than that in the non-acid-reflux type (2824 ± 1160 Ω) and functional heartburn (3546 ± 1353 Ω) groups. Baseline impedance values inversely correlated with reflux percent time, acid-reflux time, and acid exposure time.
  
  
  CONCLUSIONS
  Among patients with PPI-refractory NERD, acid-reflux type was associated with lower baseline impedance compared with non-acid-reflux type and functional heartburn.
authors.affiliation: Department of Gastroenterology, Osaka City University Graduate School of Medicine, Osaka, Japan.
authors.forename: Yukie
authors.initials: Y
authors.lastname: Kohata
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Yamagami
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tanigawa
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Shiba
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Toshio
authors.initials: T
authors.lastname: Watanabe
authors.forename: Kazunari
authors.initials: K
authors.lastname: Tominaga
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Arakawa
mesh_terms: D000328:Adult; D000368:Aged; D004351:Drug Resistance; D017097:Electric Impedance; D050782:Esophageal pH Monitoring / Q000379:methods*; D005260:Female; D005764:Gastroesophageal Reflux / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*
chemical_list: D054328:Proton Pump Inhibitors
keywords: MII-pH monitoring; PPI-refractory NERD; baseline impedance