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The overlooked clot

Many occur after patients leave the hospital, but preventive treatment is spotty.

July 30, 2007|Chelsea Martinez | Times Staff Writer

BLOOD clots can be painful, difficult to diagnose, even life-threatening. But hospital patients -- who are at an especially high risk of developing the condition -- often don't receive treatment to prevent them, researchers have found.

A hospital stay, even one as short as a few days, can greatly increase the chance of developing a clot in the legs or lungs. In fact, blood clots in the lungs, known as pulmonary embolisms, are blamed for as much as 10% of deaths in hospitalized patients. Blood clots are even more likely to develop after a patient has left the hospital.

A study in the July 23 issue of the Archives of Internal Medicine has found that less than half of patients get drug therapy to prevent the clots.

In looking at medical records of 1,897 people diagnosed with the blood clots in the Worcester, Mass., area, researchers found that 60% of the cases occurring in an outpatient setting had happened within three months of surgery or hospital stay.

Of those, 59.7% had received any type of therapy to prevent the condition while in the hospital, with almost 43% receiving anti-clotting medication and almost 17% receiving nondrug methods.

More than half of the patients who experienced blood clots after hospitalization had been in the hospital for four days or fewer, suggesting that the risk doesn't exist only for long-term patients.

The study, led by Dr. Frederick Spencer, director of clinical thromboembolism at the Chedoke Hospital at McMaster University in Ontario, Canada, says doctors should be doing more to prevent these problems, which may occur with greater frequency as the average length of hospital stays shrinks.

"The thing about blood clots is a lot of people don't even know they have them," he says. "Does it mean we need to send everybody home with anticoagulation medication? Maybe, but if we did a better job while they were in the hospital that could also prevent a lot of these cases."

Traditional therapy to reduce the risk of blood clots includes blood-thinning drugs, such as heparin or fondaparinux, or compression stockings or shoes that help improve blood flow. Clots probably cause more deaths than are recognized because they often go undiagnosed. Symptoms of blockage in the legs -- warmth, swelling and sharp pain -- can be confused with a muscle strain or tear. Untreated, the clots can lodge in the vessels of the lung, cutting off air flow and leading to suffocation.

"What we're really trying to prevent is them traveling to the lungs," Spencer says.

Dr. Peter Lawrence, chief of vascular surgery and director of the Gonda Vascular Center at UCLA, says that clotting history and blood thickness are routinely checked for patients undergoing surgery but are not commonly done for patients in the hospital for other reasons. But he says the three greatest factors that increase a person's chance of blood clot formation -- thickening of the blood, which can be triggered by some medications; venous injury, such as that from a catheter; and prolonged immobility -- are common to nonsurgical patients as well. Whenever blood flow is restricted or slowed, the enzymes that normally clean the vessel walls of potential clots don't circulate as well.

"People get a false sense of security because patients often look their best at the time of hospital discharge," says Dr. Samuel Goldhaber, a professor at Harvard Medical School who wrote an editorial accompanying the study.

Dr. Fred Weaver, chief of vascular surgery and endovascular therapy at USC, says, "The major impetus for feeling a clot is upright posture -- you might not see the blood clot until the person is up and moving again. A lot of these patients do go home and spend a lot of time in bed."

"The fact that we're moving people out of the hospital faster means we're not going to see it," he says. "Once patients go home, there is no common collective mechanism for figuring out their complications unless it brings them back to the hospital."

Spencer said he hopes that, ultimately, every doctor who releases a patient has to say yes or no to clot prevention measures. Until then, he says, patients should consider asking their physician if they could benefit from a thinner or compression sleeve. "I think that would be a reasonable thing to ask -- and it's a good reminder for the docs."

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chelsea.martinez@latimes.com

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