Do Comorbid Conditions Increase the Incidence of Venous Thromboembolism after Colorectal Surgery?

Introduction: Colorectal surgery (CRS) patients are at high risk for venous thromboembolism (VTE). The Caprini model elucidates that comorbidities compound to increase VTE risk, but this association in CRS patients remains undefined. We hypothesize that the compounding presence of comorbidities in patients undergoing colorectal resection (CRR) or small bowel resection (SBR) is associated with greater postoperative VTE risk. Methods: This study was a single-institution, retrospective review of patients undergoing CRR and/or SBR from July 2011 to July 2020. Patient demographics, baseline laboratory values, medical comorbidities, and 30-day outcomes were recorded. Incidence of 30-day preoperative or postoperative VTE, including deep venous thrombosis (DVT), pulmonary embolism (PE), portal vein thrombosis (PVT), or inferior vena cava thrombosis (IVCT), were determined. All patients received multimodal in-hospital VTE prophylaxis. After July 2017, patients at high risk for VTE received post-discharge extended chemoprophylaxis. Results: A total of 4354 patients were identified; 129 patients had a postoperative VTE. There was a high incidence of pre-existing comorbidities. In multivariate analysis, acute kidney injury (p = 0.002) and preoperative 30-day VTE (p<0.001), American Society of Anesthesiologists classification IV (p = 0.015) and V (p = 0.041), and inherited hypercoagulability states (p = 0.029) were associated with postoperative VTEs. In a logistic regression model, multiple comorbidities (p<0.001) and preoperative VTE (p<0.001) were predictive of postoperative VTE. Open SBR (p = 0.004) and open (p = 0.001) and laparoscopic (p<0.001) colectomy were associated with postoperative VTE. After July 2017, there were lower rates of postoperative VTE (p = 0.041). Conclusions: Multimorbidity is linearly associated with increased rates of postoperative VTE after CRS surgery. This high-risk population could benefit from novel in-hospital and post-hospital VTE prophylaxis measures.