Feb. 9, 2010 -- Non-hospitalized patients with a flare-up of inflammatory
bowel disease are 16 times more likely to develop potentially life-threatening
blood clots as people without the bowel disorder, new research reveals.
While the risk is still quite small for individuals with Crohn's disease and
ulcerative colitis, which are forms of inflammatory bowel disease (IBD), the
findings suggest that active IBD is a bigger risk factor for blood clots than
has been previously recognized.
Blood clots, known medically as venous thromboembolisms, can become deadly
when they break away from the large veins in the legs or groin and move to the
lungs. The Surgeon General estimates that between 300,000 and 1.2 million
Americans experience such clots each year, and more than 100,000 die from
In earlier studies, researchers reported that most IBD patients who develop
blood clots do so when their disease is symptomatic, rather than when it is in
remission. For this reason, many hospitalized IBD patients receive anticlotting
drugs like heparin to reduce their blood clot risk. But the risk to
non-hospitalized IBD patients in the active, or flare-up, phase of the disease
has not been well understood.
In an effort to assess this risk, researchers analyzed a database in the
U.K. that included information on patients with and without IBD.
The analysis included 13,756 patients treated for IBD between November 1987
and July 2001 and 71,672 people without the disease who served as a comparison
Among the results:
Overall, IBD patients were 3.4 times more likely to develop a blood clot
than people without IBD.
This risk more than doubled among patients experiencing IBD flares. These
symptomatic patients were eight times more likely to develop a clot as those
Patients hospitalized for a flare-up of IBD were three times as likely to
develop a blood clot as patients hospitalized for other reasons.
While the overall risk for developing a blood clot was greatest among
patients hospitalized with IBD, the relative risk was greatest for symptomatic
IBD patients who were not hospitalized.
Compared to non-hospitalized people without IBD, these patients were 16
times more likely to develop a potentially life-threatening blood clot.