Development and Statistical Validation of the Metabolic Surgery Indication Score (MetSIS) – Standardized Procedure Selection in Metabolic and Bariatric Surgery

Background: Sleeve Gastrectomy (SG) and One anastomosis gastric bypass (OAGB) are two of the three most performed MBS procedures worldwide. Indication for the proper surgical procedure is based on the surgeon’s choice, and no validated score for procedure selection exists. The aim of this study was to develop and validate a clinical score, which standardizes procedure selection in metabolic and bariatric surgery (MBS). Methods: Based on the importance of obesity complications and comorbidities, we created a Metabolic Surgery Indication Score (MetSIS), including ten clinical and laboratory parameters to categorize the complex disease obesity with its comorbidities: age, sex, body mass index (BMI), obstructive sleep apnea (OSAS), hypertension, dyslipidemia, type 2 diabetes mellitus, HbA1c, insulin therapy and metabolic dysfunction-associated steatotic liver disease (MASLD). Minimum score was 0 points, maximum 12 points. Retrospectively, data from all patients who underwent primary SG or OAGB in a four-year period in our center of excellence for MBS were analyzed. Exclusion criteria included reflux disease (esophagitis  C next to LA Classification) and/or the presence of hiatal hernia ( 3cm) (since these patients undergo RYGB next to the internal protocol) and revisional bariatric surgery. Results: From March 2019 to September 2023, 468 patients underwent SG (n = 363) or OAGB (n = 105) as primary bariatric procedure. Mean BMI was 42.1 kg/m2 (SG) and 48 kg/m2 (OAGB). Patients who underwent SG demonstrated lower MetSIS score, while patients who underwent OAGB had a higher score (p < 0.001). The parameters BMI (p < 0.001), presence of OSAS associated with CPAP treatment (p < 0.001), hypertension (p < 0.001), T2DM (p < 0.001), insulin requirement (p = 0.001) and MASLD (p = 0.035) were found as statistically significant parameters which influenced procedure choice. Conclusion: The MetSIS score is a simple and immediate score, which can be applied during decision making of MBS procedure in routine clinical settings. Further studies are necessary to associate this score to the real metabolic outcome during long-term follow-up.