Venous Thromboembolism Among Patients With Inflammatory Bowel Diseases is Not Related to Increased Thrombophilia: A Case-Control Study.

Goal The aim was to assess whether thrombophilia significantly contributes to the risk of venous thromboembolic events (VTEs) in patients with inflammatory bowel disease (IBD). Background Patients with IBD have a high risk of VTE. The underlying mechanism has been only partially defined. Methods A case-control study in adults with IBD and an episode of VTE (IBD-VTE) were matched and compared with non-IBD patients with a VTE (non-IBD-VTE). The study population was comprised of patients seen in 2 tertiary medical centers in Israel between 2000 and 2013. Characteristics of IBD and risk factors for VTE were retrieved from medical charts, and a comprehensive thrombophilia panel was completed in all patients. Results Forty-four IBD-VTE cases (27 Crohn's disease) were matched with 127 non-IBD-VTE controls. The majority of VTE had a clear etiology and were considered provoked events. Provoked and unprovoked VTE rates were not different between the 2 groups. Likewise, thrombophilia rates were similar among patients with IBD-VTE and controls (40.9% vs. 53.5%, respectively, P=0.14). However, among patients with unprovoked VTE, thrombophilia rates were significantly lower in the IBD-VTE group compared with controls (42.1% vs. 70.7%, respectively, P=0.03). Among patients with IBD-VTE, an unprovoked event, and negative thrombophilia, 77% had active inflammation at the time of VTE. Conclusion Thrombophilia rates are similar among patients with IBD-VTE and controls but are less common among patients with unprovoked IBD-VTE. This finding suggests that either inflammation or other novel pathways drive VTE in patients with IBD.