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.
Study researcher Matthew J. Grainge, MD, of the University of Nottingham,
and colleagues conclude that patients with symptomatic IBD who are not
hospitalized may benefit from short-term treatment with intravenous heparin or
other anticlotting drugs.
But in an editorial published with the study, University of Toronto
inflammatory bowel disease specialist Geoffrey C. Nguyen, MD, PhD, writes that
this may be premature.
He notes that treating non-hospitalized patients with daily injections of
heparin has no proven effectiveness and would add to the disease burden.
Johns Hopkins University School of Medicine IBD specialist Mark Lazarev, MD,
tells WebMD that a study comparing treatment vs. non-treatment for reducing
blood clot risk would be expensive and difficult to do.
"You would need a large number of patients because the individual risk is
very low," he says.
Stephan R. Targan, MD, who directs the IBD Center at Cedars-Sinai Medical
Center in Los Angeles, agrees it is too soon to talk about treating all
patients with symptomatic IBD to reduce their blood clot risk.
"It doesn't really make sense to talk about treating the entire population
with active IBD," he tells WebMD. "Maybe if we knew more about what predisposes
people with these conditions to develop blood clots we could target such
treatments. But right now we can't do that."
Grainge, M.J. The Lancet, Feb. 9, 2010; online edition.
News release, The Lancet.
Mark Lazarev, MD, assistant professor of medicine, Johns Hopkins University
School of Medicine, Baltimore.
Stephen R. Targan, MD, director, Inflammatory Bowel Disease Center and
division of gastroenterology, Cedars-Sinai Medical Center; professor of
medicine, David Geffen School of Medicine, University of California, Los