Roles of swallowing and belching in different phenotypes of gastroesophageal reflux disease.

Background: The contributions of swallowing and belching to specific gastroesophageal reflux disease (GERD) phenotypes are unclear.
Methods: This study retrospectively analyzed esophageal pH/impedance studies, comparing reflux events preceded by gastric belching (GB), supragastric belching (SGB), air swallowing, and liquid/solid swallowing based on reflux position, lower esophageal sphincter (LES) pressure, and acid exposure time (AET).
Key Results: 20 GERD patients and 10 controls were studied. Upright GERD patients and controls had a higher proportion of reflux events with a preceding swallow or belch (0.64, 0.64) than the supine group (0.38, p = 0.043). The upright group and controls trended toward a higher proportion of reflux events preceded by overall swallowing (0.61, 0.50) and air swallowing (0.55, 0.48) than the supine group (0.32, 0.31 p = 0.064, p = 0.11), but the three groups had similar rates of liquid/solid swallowing (0.032, 0.024, 0.017, p = 0.69). LES pressure did not correlate with reflux events preceded by swallowing (R ²  = 0.021, p = 0.44). There was a higher rate of events preceded by gastric belching in the control group (0.14) than in the upright (0.032) and supine groups (0.066, p = 0.049). LES pressure did not correlate with the rate of events preceded by belching (R ²  = 0.000093, p = 0.96). Normal AET patients had a higher rate of events preceded by GB (0.12) than those with increased acid exposure (0.030, p = 0.0083), but the two groups had similar rates of preceding air (0.43, 0.47, p = 0.68), liquid/solid (0.018, 0.032, p = 0.30), and overall swallowing (0.44, 0.53, p = 0.38).
Conclusions and Inferences: Swallowing more than belching is a dominant mechanism for reflux irrespective of GERD position, LES pressure, and AET.
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