Validation and Improvement of a Highly Predictive Bariatric Surgery Mortality Risk Calculator to Include Sleeve Gastrectomy Using MBSAQIP 2015-2017 Data

Abstract Introduction Initial development of a prominent bariatric surgery mortality risk calculator comprised of cases that now account for less than 10% of commonly performed operations. Whether the previously highly predictive model is valid with more recent data is unknown. Methods The MBSAQIP Participant Use File from years 2015 to 2017 was used for the analysis. C-statistics were calculated with observed death as the outcome and estimated 30-day mortality risk as the only predictor and receiver operating characteristic curve was plotted. Similar analyses were repeated for each body mass index (BMI) subgroup. Backward selection logistic regression was used to investigate the potential of improving the robustness of the model. Results Patients were predominantly female (n = 446,149, 80.4%) and white (n = 409,350, 73.7%) with a mean (SD) age of 45.4 (12.0) years and BMI of 44.5 (8.4) kg/m2, and the most commonly performed operation was sleeve gastrectomy (n = 338,061, 60.9%). Assessing previous model using present data, area under the curve (AUC) was 0.7412. By BMI subgroup, AUC for BMI 60 kg/m2 was 0.6576. Discussion The present study found that the model previously developed maintains discrimination with changing surgical procedures. Though variables in the initial calculator are helpful, additional factors should be considered when weighing risk such as sex, previous surgery, and renal function. Future studies are needed to determine whether changes in modifiable risk factors will impact mortality rates.