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

Gencer Kurt,1 Rune Erichsen1,2 1Department of Clinical Epidemiology and Center for Population Medicine, Aarhus University Hospital and Aarhus University, Aarhus, Denmark; 2Department of Surgery, Randers Regional Hospital, Randers, DenmarkCorrespondence: Gencer Kurt, Department of Clinical Epidemiology and Center for Population Medicine, Aarhus University Hospital and Aarhus University, Olof Palmes Allé 43-45, DK, Aarhus, 8200, Denmark, Email genkur@clin.au.dkPurpose: 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.Keywords: inflammatory bowel disease, venous thromboembolism, mortality, colectomy, cohort study