S1033 Predictors of Gastroesophageal Reflux Disease After Bariatric Surgery: A Cohort Study

Introduction: Gastroesophageal reflux disease (GERD) is common after bariatric surgery. Predictors of postoperative reflux beyond surgery and pre-operative GERD remain unclear. In this study, we aim to identify clinical variables associated with postoperative GERD in patients undergoing bariatric surgery. Methods: This was a retrospective cohort study of patients with ambulatory pH monitoring following bariatric surgery from 2010 to 2024 at a tertiary referral center. GERD was assessed by ambulatory pH monitoring with 24-hour impedance pH monitoring or 48-hour wireless pH capsule (BRAVO) and was defined as acid exposure time (AET) ≥6%. Patient demographics, pre- and postoperative body mass index (BMI), GERD symptoms, and proton pump inhibitor use were recorded. Pre- and postoperative ambulatory pH testing, esophageal manometry, esophagogastroduodenoscopy (EGD), and esophagram results were collected. Results: Forty-six patients who underwent ambulatory pH monitoring following bariatric surgery were included. Of these, N = 38 (82.6%) were women. Mean age was 52.6 ± 13.4 years at the time of reflux testing. The mean preoperative BMI was 42.9 ± 5.1, and the mean postoperative BMI at the time of testing was 32.1 ± 6.5, with a mean BMI reduction of 10.9. Twenty-seven patients (58.7%) underwent 48-hour wireless BRAVO pH testing, while N = 19 (41.3%) underwent 24-hour impedance pH monitoring. Reflux testing was performed at a median of 3.7 years (range 2.6 months to 12.7 years) following bariatric surgery. Patients who underwent Roux-en-Y gastric bypass had a lower mean DeMeester score and lower total AET (% time pH < 4) compared to those who underwent sleeve gastrectomy. Severe acid reflux, defined as acid exposure time >10%, was more common in patients with sleeve gastrectomy compared to those with Roux-en-Y (P = 0.028). The presence of a hiatal hernia on EGD or esophagram, as well as findings of esophagitis on EGD or reflux on esophagram, did not correlate with abnormal acid exposure. Preoperative BMI, postoperative BMI, and the degree of BMI change were also not associated with postoperative reflux. Conclusion: In patients undergoing ambulatory pH testing after bariatric surgery, sleeve gastrectomy was associated with higher acid exposure time and a greater proportion of patients with severe acid reflux compared to Roux-en-Y gastric bypass. This further supports type of bariatric surgery as an impactful risk factor for GERD.