Inflammatory bowel disease hikes blood clots

People with inflammatory bowel disease are at an increased risk of developing blood clots, and this risk is highest during a flare-up, researchers report online February 9 in the Lancet . Although hospitalized IBD patients have been known to have problems with clotting, the new study finds a surprisingly high risk in people dealing with an episode outside the hospital setting. IBD includes Crohn’s disease and ulcerative colitis. Although medication can bring IBD under control and keep it in remission temporarily, relapses of the disease are common and can debilitate a person. Patients often require steroid medication to knock back inflammation that causes the abdominal pain, diarrhea, vomiting and blood in the stool that mark the condition. In the new study, Matthew Grainge and his colleagues at the University of Nottingham in England analyzed medical records dating from 1987 to 2001 of more than 13,000 IBD patients and a control group of 71,000 people who didn’t have IBD. People in both groups were in their mid-40s on average and had comparable weights and smoking histories, factors that also influence blood clot formation. The researchers excluded people whose records showed a prescription for blood thinners or who might have taken steroids for other ailments, such as asthma. The scientists found that hospitalized IBD patients fending off a flare-up were three times more likely to develop venous thrombosis — a blood clot in a vein — than were hospitalized people in the control group without IBD, a finding that matches past reports. But IBD patients dealing with a flare-up outside a hospital setting were 16 times more likely than the nonhospitalized control group to develop a venous thrombosis. In absolute terms, people with IBD in the hospital were still at greater risk than those who were treated as outpatients. Even while in remission, IBD patients were twice as likely as the people who didn’t have the disease to develop such a clot. A venous thrombosis that occurs in a large vein in a leg or arm, a condition called deep-vein thrombosis, can cause pain and swelling. The chief risk is that the clot will dislodge and cause a pulmonary embolism, a blockage of one of the main arteries in the lung. That can lead to chest pain, breathing problems, loss of oxygen, abnormal heart rate, sinking blood pressure, collapse and even death. On rare occasions, according to case studies, these clots can lodge in the brain and cause strokes. The reason for increased clot risk in IBD patients remains a mystery. Steroid use might contribute to it, the authors say, but additional risk has not shown up in other groups using steroids, including people with asthma or rheumatoid arthritis. Some scientists hypothesize that the systemic inflammation that characterizes IBD might trigger clotting, but it’s not clear how, says Geoffrey Nguyen, a gastroenterologist at the University of Toronto. People in hospitals tend to be sicker and therefore have a greater risk of clotting whether they have IBD or not, Nguyen says. This may account in part for why the hospitalized IBD patients were only three times more likely to have clots than their hospitalized counterparts while the risk for the nonhospitalized IBD patients was much higher compared to nonhospitalized controls. Also, hospitalized IBD patients in this study might have received short-term regimens of blood thinners that didn’t show up on the prescription records analyzed, he notes. In any case, Nguyen says, this study should help doctors in treating people who have IBD. “It’s important for clinicians to really instruct patients that they have a condition that increases the risk of clots,” he says. To that end, he suggests that the kind of support stockings used to minimize clot formation on long airplane flights are helpful and inexpensive, Nguyen says. And most important, patients need to report promptly any swelling and pain in extremities, as these may indicate venous thrombosis, he says.