Postprandial oesophageal integrated acidity is a reliable predictor of gastro-oesophageal reflux disease

Background: Measurement of oesophageal acid exposure parameters postprandially has been shown to distinguish gastro-oesophageal reflux disease patients from normal individuals. Aims: 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). Conclusion: Postprandial oesophageal integrated acidity provides a robust estimation of oesophageal acid exposure and may predict symptoms in gastro-oesophageal reflux disease patients.