Randomized Controlled Trial of One Anastomosis Gastric Bypass Versus Roux-En-Y Gastric Bypass for Obesity: Comparison of the YOMEGA and Taiwan Studies

Background The YOMEGA study (Y-study) was a randomized trial comparing one anastomosis gastric bypass (OAGB) and Roux-en-Y gastric bypass (RYGB). Here, we aim to compare the Y-study and our pioneer trial from Taiwan (T-study). Methods Data from the Y-study and the T-study were collected and compared. Results The Y-study recruited 234 patients with a mean body mass index (BMI) of 43.9 and age of 43.5 years. The T-study recruited 80 patients with a similar mean BMI of 44.3 and mean age of 31.4 years. The studies had similar findings including (1) OAGB is easier and possibly safer procedure than RYGB. Both studies showed that OAGB had a shorter operation time than RYGB, but a lower surgical complication rate was only demonstrated in T-study. (2) Both procedures have similar weight loss but OAGB features better glycemic control than RYGB. Weight loss at 2 years after surgery was similar between two procedures, but OAGB reduced HbA1c to a greater degree than RYGB at 2 years in Y-study (- 2.3% vs. - 1.3%; p = 0.025). The resolution of the metabolic syndrome was 100% for both groups in the T-study. (3) OAGB carried a higher risk of malnutrition. OAGB had more malabsorptive problems with a lower hemoglobin level than RYGB at 2 years after surgery. Adverse malnutrition events occurred in nine (7.8%) OAGB patients in the Y-study. Four (3.4%) patients of OAGB received revision surgery in Y-study but none in T-study. (4) Bile reflux was noted in OAGB patients but did not influence quality of life or revision rate. Y-study found that bile in the gastric pouch was present in 16% of patients in the OAGB group versus none in the RYGB, but no inter-group difference in quality of life was detected. There was a trend for RYGB patients to experience more abdominal pain than OAGB. Conclusions Both studies showed that OAGB is a technically easier procedure and features better glycemic control than RYGB, but has a mal-absorptive effect. However, the bile reflux and abdominal pain controversies persisted.