title: Analyses of the Post-reflux Swallow-induced Peristaltic Wave Index and Nocturnal Baseline Impedance Parameters Increase the Diagnostic Yield of Impedance-pH Monitoring of Patients With Reflux Disease.
abstract: OBJECTIVE
  Analyses of impedance parameters such as the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI) have been proposed to increase the accuracy of diagnosis of reflux disease. We assessed whether these improve the diagnostic yield of impedance pH monitoring of reflux disease.
  
  
  METHODS
  We performed a prospective study of consecutive patients with proton pump inhibitor-responsive heartburn who underwent 24-hour impedance pH monitoring at hospitals in Italy from January 2011 through December 2013. Reviewers blindly analyzed off-therapy impedance pH tracings from 289 patients with proton pump inhibitor-responsive heartburn, 68 with erosive reflux disease and 221 with non-erosive reflux disease (NERD), along with 50 healthy individuals (controls). The PSPW index, the MNBI, the esophageal acid exposure time, the number of total refluxes, and the bolus exposure were calculated, as well as the symptom association probability (SAP) and the symptom index (SI).
  
  
  RESULTS
  In receiver operating characteristic analysis, the area under curve of the PSPW index (0.977; 95% confidence interval, 0.961-0.993) was significantly greater than that of the other impedance pH parameters in identifying patients with reflux disease (P < .001). The PSPW index and the MNBI identified patients with erosive reflux disease with the highest level of sensitivity (100% and 91%, respectively), as well as the 118 pH-positive (99% and 86%) and 103 pH-negative (77% and 56%) cases of NERD. The PSPW index and the MNBI identified pH-negative NERD with the highest level of sensitivity; values were 82% and 52% for the 65 SAP-positive and/or SI-positive cases and 68% and 63% for the 38 SAP-negative and SI-negative cases. Diagnoses of NERD were confirmed by pH-only criteria, including those that were positive on the basis of the SAP or SI, for 165 of 221 cases (75%) and by impedance pH criteria for 216 of 221 cases (98%) (P = .001).
  
  
  CONCLUSIONS
  The PSPW index and the MNBI increase the diagnostic yield of impedance pH monitoring of patients with reflux disease. Analysis of impedance pH data by calculating the PSPW index and the MNBI can increase the accuracy of diagnosis of patients with reflux disease, compared with pH-only data.
authors.affiliation: Digestive Pathophysiology Unit and Digestive Endoscopy Unit, Baggiovara Hospital, Modena, Italy. Electronic address: marziofrazzoni@gmail.com.
authors.forename: Marzio
authors.initials: M
authors.lastname: Frazzoni
authors.affiliation: Gastroenterology Unit, Department of Surgery, Oncology and Gastroenterology, University of Padova, Padova, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Savarino
authors.affiliation: Department of Translational Research and New Technology in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: de Bortoli
authors.affiliation: Department of Translational Research and New Technology in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Martinucci
authors.affiliation: Gastroenterology Unit, Department of Internal Medicine, University of Genova, Genova, Italy.
authors.forename: Manuele
authors.initials: M
authors.lastname: Furnari
authors.affiliation: Digestive Pathophysiology Unit and Digestive Endoscopy Unit, Baggiovara Hospital, Modena, Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Frazzoni
authors.affiliation: Digestive Pathophysiology Unit and Digestive Endoscopy Unit, Baggiovara Hospital, Modena, Italy.
authors.forename: Vincenzo Giorgio
authors.initials: VG
authors.lastname: Mirante
authors.affiliation: Digestive Pathophysiology Unit and Digestive Endoscopy Unit, Baggiovara Hospital, Modena, Italy.
authors.forename: Helga
authors.initials: H
authors.lastname: Bertani
authors.affiliation: Department of Translational Research and New Technology in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: Santino
authors.initials: S
authors.lastname: Marchi
authors.affiliation: Digestive Pathophysiology Unit and Digestive Endoscopy Unit, Baggiovara Hospital, Modena, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Conigliaro
authors.affiliation: Gastroenterology Unit, Department of Internal Medicine, University of Genova, Genova, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Savarino
mesh_terms: D000328:Adult; D000818:Animals; D017097:Electric Impedance; D050782:Esophageal pH Monitoring / Q000379:methods*; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000473:pathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007558:Italy; D008297:Male; D008875:Middle Aged; D010528:Peristalsis; D011446:Prospective Studies; D046388:Swallows
keywords: Esophageal Baseline Impedance; Esophageal Chemical Clearance; GERD; Heartburn; Impedance pH Monitoring; ROC AUC