Long-Term Outcomes of One-Anastomosis Gastric Bypass in Class IV and Class V Obesity: A Comparative Analysis with Sleeve Gastrectomy.

INTRODUCTION: Metabolic and bariatric surgery (MBS) is the most effective treatment for severe obesity. However, the optimal approach for patients with a BMI ≥ 50 kg/m² remains unclear. This study compares the perioperative and long-term outcomes of one-anastomosis gastric bypass (OAGB) and sleeve gastrectomy (SG) in this high-risk population. METHODS: A retrospective analysis of a prospectively maintained database was conducted, including all patients with BMI ≥ 50 kg/m² who underwent OAGB or SG at a tertiary center between 2015 and 2024. Patients with previous MBS were excluded. Baseline characteristics, perioperative complications, weight loss outcomes, and resolution of obesity-related diseases were analyzed. RESULTS: A total of 121 patients were included: 76 underwent SG, and 45 underwent OAGB. The mean preoperative BMI was higher, and the rate of men was lower in the SG group (55±5.4 vs. 52.2±2.7, p =0.0009 and 38.2% vs. 60%, p=0.024, respectively). 90-day postoperative complications did not differ between the groups (SG: 14.5% vs. OAGB: 11.1%, p = 0.78), nor did major complications rate (SG: 2.6% vs. OAGB: 0%, p = 0.53). One perioperative mortality was observed in the SG group (1.3%). At five-year follow-up, OAGB patients showed significantly greater total weight loss (36.7±11.3% vs. 27.1±13%, p=0.01). Conversion surgery trends were higher in SG (9.1% vs. 2.6%, p =0.13), primarily for weight regain. Obesity-related disease resolution rates were high and comparable between groups except for hypertension resolution which was higher in OAGB (p=0.04). CONCLUSIONS: Both OAGB and SG are safe and effective for patients with BMI ≥ 50 kg/m². providing substantial weight loss and disease improvement. In this study, OAGB was associated with higher weight loss outcomes. Larger multi-institutional studies are needed to confirm these findings.