Venous Thromboembolism After Total Colectomy in Inflammatory Bowel Disease: Risk Factors and Mortality - a Danish Population-Based Cohort Study

Purpose: Total colectomy is a key intervention in inflammatory bowel disease (IBD) management and a high-risk procedure for postoperative venous thromboembolism (VTE). We investigated risk factors for postoperative VTE and VTE-associated mortality in patients with IBD undergoing total colectomy. Patients and Methods: We conducted a population-based cohort study using Danish registries (1996-2021), including all patients with IBD who underwent total colectomy (n=5303). We calculated the 90-day cumulative risk of VTE and used Cox regression to assess the association between potential risk factors and VTE. We used the Kaplan-Meier method to calculate 1-year mortality after VTE, and we compared mortality between patients with and without VTE using Cox regression as an estimate of the mortality rate ratio. Results: The 30-day VTE risk was 0.6% in patients with Crohn's disease and 1.3% in those with ulcerative colitis. During this period, the strongest risk factors were age (adjusted hazard ratio 3.95 95% CI 1.87-8.37) for 41-60 years and 2.96 1.30-6.75 for ≥60 years vs ≤40 years), calendar year of total colectomy (3.84 1.10-13.34 for 2014-2020 vs 1996-2001), high comorbidity burden (2.14 0.94-4.88 vs low comorbidity), IBD duration <1 year (1.84 0.81-4.16 vs 1-5 years), male sex (1.56 (0.92-2.64), and corticosteroid use (1.55 0.86-2.79). In secondary analyses, comparing preoperative systemic corticosteroid use to non-use, we found a twofold higher 30-day VTE rate. Most associations persisted for 31-90 days, though with some attenuation. The 1-year mortality risk after VTE was 21.0% (hazard ratio of 7.65 95% CI, 3.12-18.73). Conclusion: Several patient and clinical factors were associated with elevated postoperative VTE risk, and VTE after total colectomy carried a substantially increased 1-year mortality. These findings may help identify high-risk subgroups and inform future studies of extended thromboprophylaxis and perioperative management in IBD.