PD549 - POSTOPERATIVE NUTRITIONAL DEFICIENCIES AFTER ONE-ANASTOMOSIS GASTRIC BYPASS VERSUS ROUX-EN-Y GASTRIC BYPASS: A SYSTEMATIC REVIEW AND META-ANALYSIS

PD549

POSTOPERATIVE NUTRITIONAL DEFICIENCIES AFTER ONE-ANASTOMOSIS GASTRIC BYPASS VERSUS ROUX-EN-Y GASTRIC BYPASS: A SYSTEMATIC REVIEW AND META-ANALYSIS

F. Simas^1,2,3, I. Figueiredo^2,4,5,*, A. Ghiletechi⁶, A. Brito-Costa^1,3,7,8, J. Oliveira Torres^5,9,10, B. Almeida Marques^1,3, J. Silva-Nunes^2,3,9,10

¹Department of Nutrition, Unidade Local de Saúde de São José, ²Multidisciplinary Unit of Bariatric and Metabolic Surgery, Curry Cabral Hospital, ³Centro Clínico Académico de Lisboa, ⁴Unidade Local de Saúde de São José, ⁵Faculdade de Medicina, Universidade de Lisboa, Lisbon, ⁶Unidade Local de Saúde Entre o Douro e Vouga, Santa Maria da Feira, ⁷Laboratório de Nutrição, Faculdade de Medicina, Universidade de Lisboa, ⁸Gabinete de Análise Epidemiológica E Estatística Do Centro de Investigação, Unidade Local de Saúde São José, ⁹Department of Endocrinology, Diabetes, and Metabolism, Unidade Local de Saúde de São José, Curry Cabral Hospital, ¹⁰Nova Medical School – Faculdade de Ciências Médicas, Lisbon, Portugal

Rationale: One-anastomosis gastric bypass (OAGB) is increasingly performed worldwide due to its technical simplicity and favorable metabolic outcomes. However, concerns remain regarding its nutritional safety profile compared with Roux-en-Y gastric bypass (RYGB). This systematic review and meta-analysis aimed to evaluate the prevalence of postoperative nutritional deficiencies after OAGB and to compare that risk between OAGB and RYGB.

Methods: A systematic review was conducted following PRISMA guidelines. Electronic databases were searched for studies reporting nutritional outcomes after OAGB or RYGB. Random-effects meta-analyses with Hartung–Knapp adjustment were used to estimate pooled prevalence rates (PP). Comparative risk between OAGB and RYGB was assessed using pooled risk ratios (RR). Heterogeneity was evaluated using the I² statistic.

Results: 30 studies were included. At 12 months after OAGB, pooled prevalence was 21.3% for protein deficiency, 6.9% for calcium, 16.5% for reduced iron, 8.8% for B12, and 23.2% for vitamin D deficiency. At 24 months, B12 and D deficiencies rose to 13.4% and 42.4%. OAGB had higher short-term risk of calcium deficiency (RR 1.86, 95% CI 1.30–2.66) and higher long-term risk of nutritional anemia (RR 1.58, 95% CI 1.15–2.18) than RYGB. No differences for other micronutrients.

Conclusion: Assuming identical nutritional counseling and supplementation, OAGB is associated with clinically relevant postoperative nutritional deficiencies and shows higher short-term risk of calcium deficiency and greater long-term risk of nutritional-deficiency anemia compared with RYGB. These differences emerge progressively, suggesting cumulative micronutrient depletion leading to anemia. These findings emphasize the need for lifelong nutritional monitoring after OAGB and support individualized bariatric procedure selection.

Disclosure of Interest: None declared