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Blood clots can be treated by injections at home

August 23, 2006

Treatment of blood clots in the deep veins of the legs or the lungs with an older, less expensive form of the anticoagulant medication heparin can be just as safe and effective as similar treatment with a newer and more expensive heparin, according to a study led by Clive Kearon, professor of medicine at McMaster University, published in the August 23 issue of JAMA (The Journal of the American Medical Association).

When injected subcutaneously (beneath the skin), unfractionated (regular) heparin was shown in a randomized trial to work just as well as subcutaneous injection of the more expensive, low-molecular weight heparin in the treatment of venous thromboembolism. Traditionally, when unfractionated heparin is used in treatment, it is administered intravenously and accompanied by coagulation monitoring, which requires hospitalization. This standard approach includes ongoing dose adjustment in response to measurement of the APTT, a test that measures how fast the blood clots in a test tube under certain conditions.

The newer low-molecular weight heparins, which are administered by injection in fixed-weight doses, have gradually been replacing unfractionated heparin.

Kearon and colleagues conducted a randomized trial to study how fixed-dose, subcutaneous injection of unfractionated heparin compared to injection with the newer heparin in the treatment of blood clots in the legs or lungs.

The study was conducted from September 1998 through February 2004 at six university-affiliated clinical centres in Canada and New Zealand. Patients in the trial received either unfractionated or low-molecular-weight heparin administered subcutaneously every 12 hours. About 70 per cent of both groups were treated as outpatients. All patients received three months of warfarin (an anticoagulant drug) therapy.

Recurrent thromboembolism occurred in 3.8 per cent of the 345 patients in the unfractionated heparin group, and in 3.4 percent of the 352 patients in the low-molecular weight heparin group. The rate of major bleeding was comparable in the two groups.

The authors estimate that drug costs for a six-day course of treatment with low-molecular-weight heparin would be $712 (US), while unfractionated heparin would cost just $37-assuming both drugs are administered in the regimens used in the study. The study indicates the potential for huge costs savings.

"Fixed-dose subcutaneous unfractionated heparin is as effective and safe as low-molecular-weight heparin for initial treatment of patients with venous thromboembolism and is suitable for treatment at home," concluded Dr. Kearon, who is a physician at Hamilton Health Sciences. "In addition, the results of this study question the value of APTT monitoring in patients who are treated with currently recommended doses of unfractionated heparin."

"We've come a long way from having to spend several weeks in hospital with an intravenous heparin drip to a possible out-patient treatment that is safe, efficient, and less expensive," says Dr. Andreas Wielgosz, spokesperson for the Heart and Stroke Foundation.

McMaster University