IBC Oxford University Oral Abstract 6 - Definition and predictors of insufficient weight loss after bariatric surgery: a retrospective cohort study

Abstract Introduction After bariatric surgery, insufficient weight loss (IWL)—a failure to achieve sufficient weight loss—is the main reason for undergoing a second revisional bariatric surgery. Not only is a standardized definition for IWL missing, but its pre-, peri, and postoperative predictor factors remain unclear. This study aims to assess rates of IWL two years after bariatric surgery, applying 4 definitions; and identify predictors of IWL to improve patient counselling regarding their prevention and optimize intraoperative bariatric procedures. Methods We conducted a single-centre retrospective cohort study with 1056 consecutive patients submitted to bariatric surgery between 2019 and 2021. Regarding IWL, the following four definitions were applied: (1) body mass index (BMI) higher than 35 kg/m2 at 24 months; (2) percentage of excess weight loss (%EWL) of less than 50% at 18 months; (3) percentage of total weight loss (%TWL) of less than 20% at 24 months; (4) percentage of alterable weight loss (%AWL) of less than 35% at 24 months. All participants were followed for at least 2 years. Univariate and multivariate analyses were performed using logistic regression to compute the odds ratio (OR) and the 95% confidence intervals (95%c.i.). Results A total of 1056 patients were included, with a mean age of 45.8 (±10.3) years, of which 82.9% were female. Significant insufficient weight loss rates ranged from 6 to 14% depending on the definition, being the %EWL the definition with the highest proportion of patients with IWL. Considering %TWL as the definition for IWL, patients with IWL had significantly longer hospital time response (adjusted odds ratio: 1.03, 95% c.i.: 1.02–1.05) and were more submitted to sleeve gastrectomy (adjusted odds ratio: 2.51, 95% c.i.: 1.46–4.30). Male gender was associated with IWL only considering the first definition (BMI > 35 kg/m2) (adjusted odds ratio: 3.55, 95% c.i.: 2.36–5.33) and the second definition (%EWL) (adjusted odds ratio: 4.43, 95% c.i.: 2.80–7.02). The multivariate analysis showed that a longer hospital response and sleeve gastrectomy were independent predictors of IWL after bariatric surgery, regardless of the definition. Conclusion The predictors of insufficient weight loss varied depending on the definition applied. However, regardless of the IWL’s definition, a longer hospital response and sleeve gastrectomy were independent predictors of insufficient weight loss after bariatric surgery.