Obesity Is Associated With Increasing Esophageal Acid Exposure in Korean Patients With Gastroesophageal Reflux Disease Symptoms

BACKGROUND/AIMS: Obesity is regarded as an important contributor to the increasing occurrence of gastroesophageal reflux disease. The aims of this study were to determine whether obesity is associated with gastroesophageal reflux in patients with gastroesophageal reflux disease and to identify the factors affecting increased acid exposure in obese patients. METHODS: We retrospectively analyzed the data of patients who underwent ambulatory 24-hour pH monitoring and esophageal manometry at Seoul St. Mary's Hospital. Obesity was classified according to the Asia-Pacific criteria. RESULTS: A total of 366 patients were analyzed; 18 were underweight, 152 normal weight, 104 overweight, and 92 obese. Obesity was more frequent in men and younger patients. The percentage time of pH < 4 in the total, upright, and postprandial periods was significantly higher in obese patients than in normal or underweight patients. The DeMeester score was also higher in obese patients. Body mass index correlated positively with reflux parameters. Multivariate analysis showed that being male and obesity were significantly associated with abnormal acid exposure (P < 0.005). The total lower esophageal sphincter length shortened as body mass index increased (P < 0.005). The gastroesophageal pressure gradient increased as body mass index increased (P < 0.05). CONCLUSIONS: Obesity is associated with increasing esophageal acid exposure. The mechanism responsible for the relationship between gastroesophageal reflux disease and obesity may be associated with shortening of the lower esophageal sphincter length and increasing the gastroesophageal pressure gradient.