Hospitalized Patients at High Risk of Vein Clots

But only half get clot-preventing treatments, researchers say

FRIDAY, July 13, 2007 (HealthDay News) -- A surprisingly large number of hospital patients run the risk of a potentially fatal vein clot, but half of them aren't getting preventive treatment, researchers report.

The clotting condition, called venous thromboembolism (VTE) involves the formation of blood clots in a vein. This can cause serious problems such as blockage of blood vessels in the leg (deep vein thrombosis) or a pulmonary embolism, the blockage of a lung artery. Studies have linked pulmonary embolism to up to 10 percent of in-hospital sudden deaths.

VTE may be a bigger threat to hospitalized Americans than once thought, the new study shows.

"We looked at 38 million discharges in a data base for U.S. hospitals and found that about one of every three people in a hospital bed in the United States arguably should be protected against VTE because they have a risk," said lead researcher Dr. Frederick A. Anderson Jr., director of the Center for Outcomes Research at the University of Massachusetts Medical School.

His team published its findings in the July issue of the American Journal of Hematology.

The report is the first to estimate the number of U.S. hospital patients at risk for VTE, Anderson said. Risk was estimated using criteria set by the American College of Chest Physicians. According to those guidelines, risk factors include a hospital stay of two days or more, the presence of severe medical or surgical conditions, older age and any operation involving general anesthesia.

The study found that, among surgery patients, 24 percent were at high risk of VTE and 17 percent were at very high risk. About half of nonsurgery patients were at some risk for VTE under those criteria.

Patients meeting the criteria should be given preventive treatment, generally an anticoagulant drug such as heparin or Coumadin, when they leave the hospital, Anderson said.

However, he and another researcher, Dr. Samuel Z. Goldhaber of Harvard Medical School, performed another study of 80 selected American hospitals and found that while 50 percent of discharged patients had VTE risk factors, only half received preventive therapy.

That paper is slated for presentation at the meeting of the International Society on Thrombosis and Hemostasis in Geneva, which brings together more than 2,000 medical experts in the field.

"This paper should have an impact, because it shows the magnitude of the problem," said Goldhaber, who wrote an editorial accompanying the report in the journal.

Physicians have traditionally separated problems caused by in-hospital pulmonary embolism from those that occur at home, Goldhaber noted. But the dividing line may not be so clear.

"A study has shown that the mass of outpatients who develop pulmonary embolism had been hospitalized or had some medical procedure during the past 90 days," Goldhaber said. "So, we can no longer think of these as separate problems."

Sudden death outside the hospital usually is attributed to a heart attack or abnormal heart rhythm, Goldhaber said, and too often doctors may not take pulmonary embolism into account. "Many of these patients are being misdiagnosed," he said.

Data on the percentage of discharged hospital patients who are at risk of VTE and who get preventive treatment remains limited, Anderson said. "We just don't have the data, even though the potential for benefit or harm is significant," he said.

The risk is highest for people undergoing orthopedic surgery, such as hip or knee replacement, Anderson said. "About 9 of every 10 orthopedic surgery patients are at risk," he said.

Preventing VTE after hospital stays could have a significant public health impact, the expert added. "Here we have a preventable cause of death in hospital patients, and we should be trying to prevent it," Anderson said.

More information

The complexities of pulmonary embolisms are explained by the U.S. National Library of Medicine.

SOURCES: Frederick A. Anderson, M.D., director, Center for Outcomes Research, University of Massachusetts Medical School, Worcester; Samuel Z. Goldhaber, M.D., professor, medicine, Harvard Medical School, Boston; July, 2007, American Journal of Hematology
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