Development of venous thromboembolic event risk calculator for metabolic and bariatric surgery patients to reduce mortality

Background: Venous Thromboembolic events (VTE) after Metabolic and Bariatric Surgery (MBS) result in significant morbidity and are the leading cause of mortality. Objective: The objective of this study was to identify patients who are at a high risk for developing VTE and who may benefit from extended chemoprophylaxis following MBS. Setting: Multi-institutional study. Methods: Using the 2015-2019 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) participant user file (PUF), we identified 696,069 patients who completed 30-day follow-up data and met the inclusion criteria. Using logistic regression analysis, we identified preoperative and postoperative risk factors associated with VTE and validated our model externally using the MBSAQIP 2020-2021 datasets (N = 273,692). The Hosmer–Lemeshow test was used for goodness of fit and calibration. We also compared our model's discriminatory capability with that of other VTE risk assessment tools. We then used these risk factors to create an online open source application. Results: The overall incidence of VTE after MBS in the 696,069 (MBSAQIP 2015-2019 database) patients included in our analysis was .40% (2759 patients). Our model had a good predictive capability, with a C-statistic of .66. Our model also demonstrated good fit with a Hosmer–Lemeshow chi-square of 11.06 (P = .198). A cut-off point of .4% resulted in a sensitivity of 48.28%, with 24% of patients having a VTE risk greater than .4% within the 2015-2019 MBSAQIP dataset. Among all the perioperative factors selected in the PUF, high risk for VTE included African American race (adjusted odds ratios [AOR] 1.625, P < .0001), operation length in minutes (AOR: 1.003, P < .0001), preop functional status (AOR 1.012, P = .007), procedure type (Roux en Y Gastric Bypass; AOR .768, P < .0001 and RBS; AOR .758, P = .019 with respect to sleeve), preop body mass index (BMI) (AOR 1.012, P < .001), history of pre-op vein thrombosis requiring therapy (AOR 5.041, P < .0001), post-op superficial or organ space surgical site infection (AOR 2.713, P < .0001), preop venous stasis (AOR 1.425, P = .019),at least one readmission within 30 days(AOR 1.583, P < .0001), or at least one reoperation within 30 days (AOR 4.399, P < .0001). Conclusion: VTE after MBS can result in increased mortality rates. High-risk patients might benefit from extended chemoprophylaxis. Our model suggests that patients with a VTE risk ≥ .4% in the first 30 days following surgery may benefit from extended chemoprophylaxis.