Even though more blood clots, or venous thromboembolisms are diagnosed during the three months after patients’ hospitalizations than while they are in hospital, fewer than half of them receive medications to prevent blood clots while they are inpatients, according to a new report published in Archives of Internal Medicine (a JAMA/Archives journal), July 23 issue.

Researchers examined the results of several previous studies and found that both unfractionated and low-molecular-weight heparin are effective in preventing venous thromboembolisms in the legs and lungs of hospitalized patients.

According to background information in this study, venous thromboembolism and pulmonary embolism are major causes of complications and death among hospitalized patients. It is estimated that up to 10% of hospital deaths may be attributed to pulmonary embolism. Venous thromboembolisms, on the other hand, tend to happen out of the hospital.

Frederick A. Spencer, M.D., McMaster University Medical Center, Hamilton, Ontario, Canada, and team looked at the medical records of people from Worcester, Massachusetts, who were diagnosed with venous thromboembolism during 1999, 2001 and 2003.

The authors wrote that “A total of 1,897 subjects had a confirmed episode of venous thromboembolism. In all, 73.7 percent of patients developed venous thromboembolism in the outpatient setting; a substantial proportion of these had undergone surgery (23.1 percent) or hospitalization (36.8 percent) in the preceding three months.” 67% of all those patients experienced venous thromboembolisms within one month of their hospitalization. Two other risk factors were active cancer (29%) and a previous blood clot (19.9%).

The authors wrote “Because most of the cases of venous thromboembolism occurred within 29 days of hospital discharge (41% 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 (such as, compression stockings, pneumatic compression devices and, in high-risk patients, anticoagulants.”

The study states that about half of the outpatients who experienced venous thromboembolism after hospitalization had been in hospital for four days or less. They indicate that patients who are in hospital for a short time should receive preventative therapy. As hospital stays are getting shorter, patients are spending more recovery time at home without moving about – they would benefit from anti-clotting therapy even after discharge.

Another meta-analysis, carried out by Lironne Wein, Monash University and Alfred Hospital, Melbourne, Australia, and colleagues, looked at 36 previously published randomized controlled trials which compared drugs used to prevent venous thromboembolism – comparisons were made against a control group who did not receive prophylactic therapy. 14 of the studies compared unfractionated heparin with a control, 11 compared low-molecular weight heparin to a control, 10 compared two types of heparin to each other, and 1 compared fondaparinux sodium to a placebo.

The findings were as follows:
Unfractionated heparin was linked to a 67% lower deep vein thrombosis risk and a 36% lower pulmonary embolism risk, compared to control groups.
Low-molecular-weight heparin was linked to a 44% % lower deep vein thrombosis risk and a 63% lower pulmonary embolism risk, compared to control groups.
Fondaparinux was shown to be effective in preventing venous thromboembolism.
When compared with each other, low-molecular-weight heparin was associated with a 32% lower risk of deep vein thrombosis and a 53% lower rate of hematoma at the injection site.
Prophylactic therapy, however, was not linked to lower mortality rates.
The authors wrote “This meta-analysis has shown that unfractionated heparin and low-molecular-weight heparin are both associated with a reduced risk of venous thromboembolism in medical patients, with low-molecular-weight heparin being more effective in preventing deep vein thrombosis than unfractionated heparin when considering trials that directly compared the two agents. The unfractionated heparin dosage of 5,000 units three times daily was more effective than the unfractionated heparin dosage of 5,000 units twice daily in reducing the risk of deep vein thrombosis. We believe that routine prophylactic anticoagulation has an important place in the medical setting.”

“Although such therapy may not necessarily decrease mortality among hospitalized medical patients, it will reduce the occurrence of deep vein thrombosis and pulmonary embolism and therefore the burden of illness currently caused by these events.”

“Venous Thromboembolism in the Outpatient Setting”
Frederick A. Spencer, MD; Darleen Lessard, MS; Cathy Emery, RN; George Reed, PhD; Robert J. Goldberg, PhD
Arch Intern Med. 2007;167:1471-1475
Click here to view abstract online

Related Articles:

Editorial:
“Outpatient Venous Thromboembolism – A Common But Often Preventable Public Health Threat”
Arch Intern Med. 2007;167:1451-1452.
Click here to read the first 150 words of the full text

“Pharmacological Venous Thromboembolism Prophylaxis in Hospitalized Medical Patients: A Meta-analysis of Randomized Controlled Trials”
Lironne Wein, Sara Wein, Steven Joseph Haas, James Shaw, and Henry Krum
Arch Intern Med. 2007;167:1476-1486.
Click here to view abstract online

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