title: Postprandial oesophageal integrated acidity is a reliable predictor of gastro-oesophageal reflux disease.
abstract: BACKGROUND
  Measurement of oesophageal acid exposure parameters postprandially has been shown to distinguish gastro-oesophageal reflux disease patients from normal individuals.
  
  
  OBJECTIVE
  To calculate the accuracy of postprandial oesophageal integrated acidity in diagnosing gastro-oesophageal reflux disease.
  
  
  METHODS
  Ambulatory 24-h pH studies of 626 patients were analysed retrospectively. Gastro-oesophageal reflux disease, defined as pH < 4 for > 4.2% of time, was identified in 305 subjects. Postprandial oesophageal integrated acidity was measured for 2 and 3 h after the largest meal peak as determined from gastric pH. Postprandial symptom-associated probability was calculated.
  
  
  RESULTS
  Gastro-oesophageal reflux disease subjects had a greater postprandial oesophageal integrated acidity than non-gastro-oesophageal reflux disease subjects [median (IQR): 0.57 (0.08-2.66) vs. 0.03 (0.01-0.15) mmol*h/L]. Median postprandial oesophageal integrated acidity did not differ with gender or age in gastro-oesophageal reflux disease and non-gastro-oesophageal reflux disease subjects (P > 0.05 for all). A 3-h postprandial oesophageal integrated acidity value of 0.121 mmol*h/L had a 71.1% sensitivity and 71.7% specificity in diagnosing gastro-oesophageal reflux disease. Gastro-oesophageal reflux disease subjects with symptoms had a higher postprandial oesophageal integrated acidity than those without (P = 0.043), whereas non-gastro-oesophageal reflux disease subjects with and without symptoms did not differ (P = 0.74). The correlation between symptom-associated probability and postprandial oesophageal integrated acidity was poor (gastro-oesophageal reflux disease: r = 0.15; non-gastro-oesophageal reflux disease: r = 0.25).
  
  
  CONCLUSIONS
  Postprandial oesophageal integrated acidity provides a robust estimation of oesophageal acid exposure and may predict symptoms in gastro-oesophageal reflux disease patients.
authors.affiliation: Division of Gastroenterology, University of Pennsylvania Health Systems, Philadelphia, PA 19104, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Shih
authors.forename: C M
authors.initials: CM
authors.lastname: Brensinger
authors.forename: D A
authors.initials: DA
authors.lastname: Katzka
authors.forename: D C
authors.initials: DC
authors.lastname: Metz
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000553:Ambulatory Care; D015331:Cohort Studies; D004947:Esophagus / Q000502:physiology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity