Discharged Hospital Patients Run Risk of Blood Clots

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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.

"Although these agents reduce thrombotic events, they do not reduce all-cause mortality, perhaps because many events are not life-threatening or because of other mortality risks or because adverse events of these agents offset their benefits," said lead researcher Dr. Henry Krum, a professor of epidemiology at Monash University, in Melbourne, Australia.

Compared with a placebo, unfractionated heparin was linked to a 67 percent lower risk of venous thrombosis and a 36 percent lower risk of pulmonary embolism. Low-molecular-weight heparin was associated with a 44 percent lower risk of deep vein thrombosis and 63 percent lower risk of pulmonary embolism, the researchers found.

When compared with each other, low-molecular-weight heparin was associated with a 32 percent reduced risk of deep vein thrombosis and a 53 percent lower rate of hematoma at the injection site. Fondaparinux sodium also prevented venous thromboembolism. But, using these drugs wasn't associated with lower death rates, according to the study results.