The Impact of Hospital Volume on Bariatric Surgery Safety: a population-based study using data from the National Bariatric Surgery Registry of the United Kingdom

Background Hospital procedural volume is recognised as an important determinant of outcomes in complex surgery. However, the volume–outcome relationship in bariatric surgery remains incompletely defined. This study examined the association between hospital procedural volume and major complications in primary metabolic bariatric surgery using the United Kingdom (UK) National Bariatric Surgery Registry (NBSR). Methods Prospectively collected NBSR data from 2014–2023 were analysed. Adults undergoing RYGB, SG, or OAGB were included. Hospitals were stratified into quartiles using a four-year moving average of annual procedural volume. Primary outcomes were major postoperative complications, including gastrojejunal obstruction, bleeding, and Clavien-Dindo grade ≥ III events. Multivariable logistic regression assessed associations between hospital volume and outcomes. Results A total of 54,195 patients were included (RYGB: 23,139; SG: 25,300; OAGB: 4,744). Complication rates were low overall. For RYGB, obstruction rates declined with increasing hospital volume (0.8% in quartile I vs. 0.2% in quartile IV; p < 0.001). Higher volume independently predicted lower risk of obstruction (OR 0.31, 95% CI 0.16–0.58; p < 0.001) and Clavien-Dindo ≥ III complications (OR 0.71, 95% CI 0.51–0.99; p = 0.044). No significant associations between volume and outcomes were observed for SG or OAGB. Conclusion Higher hospital volume was associated with fewer severe complications following RYGB, supporting centralisation of complex bariatric procedures. Outcomes for SG and OAGB were consistently favourable across all volume quartiles, indicating a lesser influence of hospital volume. Minimum volume standards within bariatric accreditation frameworks may enhance patient safety.