MONDAY, July 23 (HealthDay News) -- Most blood clots occur in the months after leaving the hospital, but few patients are given medications to prevent them while they are hospitalized, a new study finds.
However, even though anti-clotting drugs prevent the majority of cases of clots, called venous thromboembolism, they don't reduce the rate of death among patients, according to a second study.
Both reports are published in the July 23 issue of the Archives of Internal Medicine..
One expert thinks these studies shed light on an important and pervasive problem.
"What happens in the hospital doesn't stay in the hospital," said Dr. Samuel Z. Goldhaber, of Brigham and Women's Hospital in Boston, and author of an accompanying editorial in the journal. "There are important ramification for the 90 days following hospital discharge in terms of developing pulmonary embolism," he said.
Goldhaber said the studies have important implications for treatment.
"There is a unique opportunity to improve patient safety by aggressively implementing prophylaxis in the hospital that will yield a return by not only lowering the rate of inpatient thromboembolism, but also prevent the development of thromboembolism in the first few months after hospital discharge," he said.
Blood clots include deep vein thrombosis -- clots in the deep veins of the legs and pelvis -- and pulmonary embolism -- clots in the lungs -- and they are a major cause of complications and death in hospitalized patients. In fact, 10 percent of deaths in the hospital are due to pulmonary embolism.
In one study in the journal, lead researcher Dr. Frederick A. Spencer, of McMaster University Medical Center in Hamilton, Ontario, Canada, and colleagues studied the medical records of patients from Worcester, Mass., who were diagnosed with venous thromboembolism in 1999, 2001 and 2003.
Spencer's team found a total of 1,897 cases of venous thromboembolism. Among these patients, 73.7 percent developed their clot after leaving the hospital. Among these patients, 23.1 percent had undergone surgery, and 36.8 percent had been hospitalized in the three months before their clot developed.
Among patients who developed clots, 67 percent had the condition within one month of their hospitalization. Other risk factors for clots were having cancer and having had a previous blood clot.
For patients with venous thromboembolism, 59.7 percent received therapy to prevent clots while in the hospital, the researchers found.
"Because most of the cases of venous thromboembolism occurred within 29 days of hospital discharge (and 41 percent occurred within 14 days), it is not unreasonable to assume that some of these cases may have been prevented simply by increased use of appropriate in-hospital deep vein thrombosis prophylaxis (e.g., compression stockings, pneumatic compression devices and, in high-risk patients, anticoagulants)," the authors wrote.
The second study in the journal looked at 36 published research papers dealing with medications used to prevent venous thromboembolism. The studies compared the blood-thinner unfractionated heparin to a placebo, or low-molecular-weight heparin with a placebo, or both types of heparin with each other. One study compared the blood-thinning drug fondaparinux sodium with a placebo.