Clinical Report: One-Anastomosis Gastric Bypass (OAGB) 2025 Review and Meta-Analysis

Overview

One-anastomosis gastric bypass (OAGB) is a widely performed bariatric procedure with growing evidence supporting its long-term efficacy in weight loss and metabolic improvements. This comprehensive review and meta-analysis evaluates indications, outcomes, and complications after five years, highlighting both benefits and concerns such as bile reflux and nutritional deficiencies.

Background

OAGB is among the top three primary metabolic and bariatric surgeries globally and has been recognized by major surgical societies including IFSO and ASMBS. It is effective for severe obesity and can be used as a revisional procedure after restrictive surgeries. While short- and mid-term outcomes are promising, long-term data on weight loss, diabetes remission, and complications remain critical for patient selection and management. This study systematically reviews literature up to April 2025 to provide updated evidence on OAGB outcomes.

Data Highlights

The meta-analysis included studies with at least 5 years of follow-up and over 100 patients, focusing on weight loss, metabolic outcomes, and complications. Key findings include significant BMI reduction, improved HbA1c levels, and a 28% higher 5-year remission rate of type 2 diabetes compared to other bariatric procedures. Complication rates such as bile reflux, vitamin deficiencies, and marginal ulcers were also analyzed, with revisional surgery rates remaining relatively low.

Key Findings

• OAGB achieves effective long-term weight loss and metabolic improvements, including significant HbA1c reduction.
• Five-year remission rates of type 2 diabetes are approximately 28% higher with OAGB compared to Roux-en-Y gastric bypass and sleeve gastrectomy.
• Long-term complications include bile reflux, malnutrition, vitamin D and iron deficiencies, and marginal ulcers.
• Some studies report increased gastroesophageal reflux disease (GERD) and need for conversion to Roux-en-Y gastric bypass due to reflux and nutritional issues.
• Despite complications, the overall rate of revisional surgery after OAGB remains relatively low and acceptable in mid- to long-term follow-up.
• Patient selection and indication criteria for OAGB continue to be important considerations to optimize outcomes.

Clinical Implications

Clinicians should consider OAGB as a safe and effective option for severe obesity and metabolic disease, especially given its superior diabetes remission rates. However, careful patient selection and monitoring for long-term complications such as bile reflux and nutritional deficiencies are essential. Regular follow-up and management strategies can help mitigate risks and reduce the need for revisional surgery.

Conclusion

OAGB represents a validated bariatric procedure with strong long-term efficacy in weight loss and metabolic control. While some complications persist, the procedure’s benefits and acceptable safety profile support its continued use with appropriate patient selection and follow-up.

References

1. International Federation for the Surgery of Obesity (IFSO) 2021 -- Recognition of OAGB
2. American Society for Metabolic and Bariatric Surgery (ASMBS) 2023 -- Endorsement of OAGB
3. Meta-analyses 2025 -- Weight loss and HbA1c reduction after OAGB
4. Systematic Review and Meta-Analysis 2025 -- Long-term outcomes and complications of OAGB