Prophylaxis for Thromboembolism in Hospitalized Medical Patients
Charles W. Francis
(N Engl J Med, 356:1438-1444, 2007)
Department of Hematology and Oncology, University of Rochester, Medical Center, Rochester, NY.
Approximately 25% of all cases of venous thromboembolism occur in hospitalized patients, and more than half of those affected are on the medical service. Because death from pulmonary embolism usually occurs before the diagnosis is suspected, primary prophylaxis should be administered when specific risk factors for thromboembolism are present. Methods of risk assessment, choices of prophylactic therapies, and guidelines for hospitalized patients at risk are discussed in this clinical practice report.
All patients should undergo risk assessment at admission and a reassessment if their status changes. Acute conditions that increase risk for venous thromboembolism are infectious disease, myocardial infarction, and respiratory disease. Stroke, congestive heart failure, rheumatic disease, and inflammatory bowel disease are additional risk factors. Clinical characteristics associated with risk include older age, previous venous thromboembolism, recent surgery or trauma, immobility, and obesity. In general, prophylaxis should be considered for medical service patients who have at least 1 risk factor, are older than 40 years, and have had limited mobility for 3 days or more.
Prophylactic therapy improves venous flow or reduces blood coagulability. Ambulation, exercises involving foot extension, and graduated compression stockings are nonpharmacologic methods of choice. The most cost-effective medication is unfractionated heparin (5000 U subcutaneously, every 8 hours); more expensive are low-molecular-weight heparins (enoxaparin and dalteparin) and fondaparinux. Trials have found such prophylaxis beneficial, especially for the highest risk patients. Studies indicate, however, that prophylaxis for venous thromboembolism is underused in hospitalized patients.
Although there is strong evidence that anticoagulant prophylaxis reduces the risk of asymptomatic deep-vein thrombosis and proximal deep-vein thrombosis in hospitalized patients with known risk factors, the application of these findings to heterogeneous populations is uncertain. There is also uncertainty regarding the best prophylactic treatment, but heparin is recommended in the absence of a contraindication for patients with several risk factors. Graduated compression stockings or pneumatic compression devices are a reasonable alternative for patients at high risk for bleeding or with active gastrointestinal or intracranial bleeding.