Exclusion of the meal period improves the clinical reliability of esophageal pH monitoring.

Meal period exclusion from 24-h pH testing allows better separation between controls and patients with gastroesophageal reflux disease. We reviewed the results of 24-h pH studies of 350 patients with reflux symptoms. They were divided into two groups based on the 95th percentile of the total percentage of time when pH was < 4 for healthy persons in our laboratory. Thus group A consisted of 212 patients with symptoms and normal acid exposure and group B consisted of 138 patients with symptoms and abnormal acid exposure. The change in upright reflux excluding the meal period was calculated for each patient. Meal period exclusion resulted in opposite effects for the two groups of patients, with a change in median upright reflux of -0.6% for group A and +0.5% for group B (p < 0.0001). After meal exclusion, five patients were reclassified as having reflux, with four (80%) of these responding to antireflux therapy. Nine other patients were recategorized as not having reflux after meal exclusion. Only one of seven patients (14%) for whom data were available responded to treatment (two patients were lost to follow-up). We recommend meal period exclusion from pH analysis because it improves the clinical reliability of esophageal pH monitoring.