Heparin Prophylaxis for Medical Patients?

Pulmonary embolism causes or contributes to 200 000 deaths each year in the United States and is considered the most common preventable cause of hospital deaths [1]. Because the first manifestation of venous thromboembolism is often fatal pulmonary embolism and because most deaths occur within the first half hour, mortality is not sufficiently improved by therapy begun after diagnosis. Prophylactic measures against deep venous thrombosis and associated pulmonary embolism have therefore been advocated for many groups of hospitalized patients.

Most studies and recommendations on prophylaxis of venous thromboembolism have involved low-dose heparin. It is available either in the standard unfractionated form, usually given subcutaneously two or three times a day, or as low-molecular-weight heparin, a derivative of unfractionated heparin with more predictable and prolonged activity that can be given subcutaneously once a day. Although it was hoped that low-molecular-weight heparin would be more effective than unfractionated heparin for prophylaxis, four randomized trials in medical patients [2-5] and numerous studies in general surgery patients [6, 7] have shown no consistent differences between the two preparations in resulting venous thromboembolism, bleeding, or death. I therefore consider unfractionated heparin and low-molecular-weight heparin together. Intermittent pneumatic compression and graduated elastic compression stockings have been shown to reduce the rate of asymptomatic deep venous thrombosis in surgical patients and are reviewed elsewhere [8].

Heparin prophylaxis is well established for most surgical patients. A meta-analysis of randomized trials in more than 14 000 surgical patients showed a statistically significant reduction in deep venous thrombosis, pulmonary embolism, fatal pulmonary embolism, and total mortality with low-dose heparin [9]. The situation for hospitalized medical patients is far less certain, and the many differences between surgical and medical patients (for example, compared with surgical patients, medical patients have generally lower rates of thromboembolic disease, higher rates of …