Inflammatory Bowel Disease Raises Blood Clot Risk

Jennifer Warner

February 28, 2011

February 25, 2011 — Inflammatory bowel disease may more than double the risk of a serious blood clot in the legs or lungs, according to a new study.

Inflammatory bowel disease (IBD) is an umbrella term that includes a variety of intestinal disorders, such as Crohn’s disease and ulcerative colitis.

Researchers found that children and adults with IBD were more than twice as likely to develop a dangerous type of blood clot that develops in the leg, known as deep vein thrombosis (DVT), or lung, called pulmonary embolism (PE).

These types of blood clots affect about two out of every 1,000 people in developed countries each year, and the risk generally increases with age.

But in this study, researchers found the results showed the relative risk of blood clots associated with IBD was particularly high among young people.

In people aged 20 and younger, the relative risk of a pulmonary embolism was six times higher among people with inflammatory bowel disease, compared to similarly aged people without IBD.

IBD Raises Clot Risk

The study compared the risk of pulmonary embolism and deep vein thrombosis in 49,799 Danish adults and children with IBD and more than 477,000 Danish people without IBD, who were followed from 1980 to 2007.

After accounting for other factors known to increase the risk of blood clots, such as a broken bone, cancer, surgery, or pregnancy, researchers found that the risk of pulmonary embolism and deep vein thrombosis was twice as high in people with IBD compared to people without IBD.

In a further analysis, researchers also took into account chronic medical conditions associated with an increased risk of blood clots, including heart disease, diabetes, congestive heart failure, and the use of hormone replacement therapy or antipsychotic drugs. They found that the risk of blood clots still remained up to 80% higher among people with IBD.

Researcher Michael Kappelman, MD, of the University of North Carolina at Chapel Hill and colleagues say the results confirm previous studies that have shown that IBD increases the risk of blood clots. In addition, they suggest that inflammatory bowel disease may be an independent risk factor for blood clots that in some cases may benefit from preventive treatment.


Kappleman, M. Gut, published online Feb. 21, 2011.

News release, British Medical Journals.


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