The Incidence of Deep Venous Thrombosis and Pulmonary Embolism among Patients with Inflammatory Bowel Disease: A Population-based Cohort Study
Charles N. Bernstein (1) , James F. Blanchard (2, 3) , Donald S. Houston (1) , Andre Wajda (2, 3)
Departments of Internal Medicine (1) and Community Health Sciences (2) , University of Manitoba and Epidemiology Unit (3) , Winnipeg, Manitoba, Canada
Background: There is an impression mostly from specialty clinics
that patients with inflammatory bowel disease (IBD) have an increased
risk of venous thromboembolic disorders. Our aim was to determine the
incidence of deep venous thrombosis (DVT) and pulmonary embolism
(PE) from a population-based database of IBD patients and, to compare
the incidence rates to that of an age, gender and geographically matched
population control group.
Methods: IBD patients identified from the administrative claims
data of the universal provincial insurance plan of Manitoba were
matched 1:10 to randomly selected members of the general population
without IBD by year, age, gender, and postal area of residence using
Manitoba Health’s population registry. The incidence of hospitalization
for DVT and PE was calculated from hospital discharge abstracts using
ICD-9-CM codes 451.1, 453.x for DVT and 415.1x for PE. Rates were
calculated based on person-years of follow-up for 1984-1997. Comparisons
to the population cohort yielded age-adjusted incidence rate ratios
(IRR). Rates were calculated based on person-years of follow-up
(Crohn’s disease = 21,340, ulcerative colitis = 19,665) for 1984-1997.
Results: In Crohn’s disease the incidence rate of DVT was
31.4/10,000 person-years and of PE was 10.3/10,000 person-years. In
ulcerative colitis the incidence rates were 30.0/10,000 person-years for
DVT and 19.8/10,000 person-years for PE. The IRR was 4.7 (95% CI,
3.5-6.3) for DVT and 2.9 (1.8-4.7) for PE in Crohn’s disease and 2.8
(2.1-3.7) for DVT and 3.6 (2.5-5.2) for PE, in ulcerative colitis. There
were no gender differences for IRR. The highest rates of DVT and PE
were seen among patients over 60 years old; however the highest IRR
for these events were among patients less than 40 years.
Conclusion: IBD patients have a threefold increased risk of developing
DVT or PE.