title: Time esophageal pH < 4 overestimates the prevalence of pathologic esophageal reflux in subjects with gastroesophageal reflux disease treated with proton pump inhibitors.
abstract: BACKGROUND
  A Stanford University study reported that in asymptomatic GERD patients who were being treated with a proton pump inhibitor (PPI), 50% had pathologic esophageal acid exposure.
  
  
  OBJECTIVE
  We considered the possibility that the high prevalence of pathologic esophageal reflux might simply have resulted from calculating acidity as time pH < 4.
  
  
  METHODS
  We calculated integrated acidity and time pH < 4 from the 49 recordings of 24-hour gastric and esophageal pH from the Stanford study as well as from another study of 57 GERD subjects, 26 of whom were treated for 8 days with 20 mg omeprazole or 20 mg rabeprazole in a 2-way crossover fashion.
  
  
  RESULTS
  The prevalence of pathologic 24-hour esophageal reflux in both studies was significantly higher when measured as time pH < 4 than when measured as integrated acidity. This difference was entirely attributable to a difference between the two measures during the nocturnal period. Nocturnal gastric acid breakthrough was not a useful predictor of pathologic nocturnal esophageal reflux.
  
  
  CONCLUSIONS
  In GERD subjects treated with a PPI, measuring time esophageal pH < 4 will significantly overestimate the prevalence of pathologic esophageal acid exposure over 24 hours and during the nocturnal period.
authors.affiliation: Stanford University School of Medicine, Stanford, CA, USA. lgerson@stanfordmed.org
authors.forename: Lauren B
authors.initials: LB
authors.lastname: Gerson
authors.forename: George
authors.initials: G
authors.lastname: Triadafilopoulos
authors.forename: Peyman
authors.initials: P
authors.lastname: Sahbaie
authors.forename: Winston
authors.initials: W
authors.lastname: Young
authors.forename: Sheldon
authors.initials: S
authors.lastname: Sloan
authors.forename: Malcolm
authors.initials: M
authors.lastname: Robinson
authors.forename: Philip B
authors.initials: PB
authors.lastname: Miner
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Gardner
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles / Q000627:therapeutic use; D002940:Circadian Rhythm / Q000502:physiology*; D050782:Esophageal pH Monitoring; D004947:Esophagus / Q000503:physiopathology*; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000188:drug therapy* / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009853:Omeprazole / Q000627:therapeutic use; D011237:Predictive Value of Tests; D015995:Prevalence; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*; D064750:Rabeprazole; D012189:Retrospective Studies
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D054328:Proton Pump Inhibitors; D064750:Rabeprazole; D009853:Omeprazole