620 Outcomes of One Anastomosis Gastric Bypass Conversion to Roux-en-Y Gastric Bypass for Morbid Obesity: A Systematic Review and Meta-Analysis

Abstract

Abstract Introduction One anastomosis or ‘mini’ gastric bypass (OAGB) is a highly effective procedure to treat morbid obesity. However, conversion to Roux-en-Y gastric bypass (RYGB) for OAGB-related complications such as bile reflux is increasing. We therefore conducted the first systematic review to determine the weight outcomes, safety and efficacy associated with OAGB-RYGB conversion surgery. Method A systematic search was conducted by three independent reviewers using Medline, Embase and the Cochrane library following PRISMA guidelines. Data extracted included patient demographics, weight, and reflux outcomes. Risk of bias was assessed using the Newcastle-Ottawa scale. The mean BMI difference was analysed using a random effects model. This study was registered on PROSPERO (Registration ID: CRD42022379759). Results 6 studies were selected which included data from 134 patients undergoing OAGB-RYGB conversion surgery. Follow-up ranged from 6-60 months. Patients' baseline BMI at conversion was 30.2 (S.D. 2.85). Common indications for conversion surgery were reflux (47.8%), malnutrition (31.3%) and inadequate weight loss (8.2%). Biliopancreatic limb length ranged from 50-200cm. Weighted mean of study outcomes demonstrated biliary reflux symptoms resolved in 90.9% cases (95 % CI 78.8-n100%). Studies reporting BMI at >24 months reported overall stable medium-term weight (mean BMI difference -0.71 (-4.03-2.61)) with moderate study heterogeneity (I2 = 82%). The rate of major post-op complications was 14.7% (6.25%-23.1%). Conclusions OAGB to RYGB conversion surgery is associated with a high resolution of reflux symptoms. However, it is associated with weight regain, albeit this may be acceptable to patients to treat biliary reflux as the weight gain is small and stable over the long-term.