"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.
"These medications should be given to reduce thrombotic events, but do not expect to reduce mortality," Krum said.
Goldhaber believes that patients need to take an active role in making sure they are receiving treatment to prevent blood clots. "Patients should demand, during hospitalization, to know what is being done to prevent thromboembolism during this period of risk," he said.
For more information on deep vein thrombosis, visit the U.S. National Heart, Lung, and Blood Institute.
SOURCES: Henry Krum, M.B.B.S., Ph.D., professor of epidemiology, Monash University, Melbourne, Australia; Samuel Z. Goldhaber, M.D., Brigham and Women's Hospital, Boston; July 23, 2007, Archives of Internal Medicine