Venous Thromboembolism in Patients with Inflammatory Bowel Disease: An Analysis by Severity of Illness

Introduction: Patients with inflammatory bowel disease (IBD) have chronic inflammation of the gastrointestinal tract, which confers a higher risk of developing venous thromboembolism (VTE) compared to individuals without IBD. Current guidelines advocate routine VTE prophylaxis for hospitalized IBD patients, but utilization remains inconsistent. This study evaluates the incidence of VTE in hospitalized IBD patients by severity of illness (SOI) to generate real-world evidence that may guide adherence to prophylaxis guidelines and inform future risk-based prevention protocols. Methods: We utilized data from the 2020 National Inpatient Sample (NIS) database, the largest inpatient care database in the USA. All patients aged ≥18 years with primary diagnosis of IBD, identified by ICD-10 codes, were included. SOI was defined using the All Patient Refined Diagnosis Group (APR-DRG) SOI: minor, moderate, major, and extreme. VTE was identified by the ICD-10 codes for deep vein thrombosis (DVT) and pulmonary embolism (PE). Baseline demographics of study participants were obtained. The primary outcome studied was the incidence of VTE graded by disease severity. Logistic regression analysis was used to calculate odds of VTE in study participants based on SOI adjusted for baseline characteristics. Sampling weights were applied to generate nationally representative estimates. Results: A total of 252,485 patients met criteria and were included. The incidence of VTE increased with increasing SOI. The incidence of VTE in patients with minor SOI was low at 0.4% compared to 7.6% in patients with extreme SOI. The incidence of DVT and PE showed similar trends across SOI. The adjusted odds ratios of VTE in patients admitted with moderate, major, and extreme SOI were 2.9 (95% confidence interval [CI]: 2.1–3.9), 10.2 (95% CI: 7.4–13.9), and 20.8 (95% CI: 14.8–29.8) compared to that of patients admitted with minor SOI. Conclusion: Our findings demonstrate a clear relationship between illness severity and VTE risk, reinforcing current guidelines that recommend thromboprophylaxis for all hospitalized IBD patients. Ensuring consistent implementation, especially in patients with severe illness, is essential to preventing avoidable complications.