Authors' objectives:

Venous thromboembolism (VTE), thrombosis in the venous vasculature, causes considerable morbidity and mortality, and diagnosis and treatment are challenging. In this report we sought to summarize evidence on the following questions: 1) What are the efficacy and safety of low molecular weight heparin (LMWH) compared to unfractionated heparin (UFH) for treatment of deep venous thrombosis (DVT)? 2) What are the efficacy and safety of LMWH compared to UFH for treatment of pulmonary embolism (PE)? 3) What are the efficacy, safety, and cost-effectiveness of outpatient versus inpatient treatment of DVT with LMWH or UFH? 4) What is the optimal duration of treatment for DVT and PE? 5) How accurate are clinical prediction rules used for the diagnosis of DVT or PE? 6) What are the test characteristics of ultrasonography for diagnosis of DVT? 7) What are the test characteristics of helical computerized tomography (CT), magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA) for diagnosis of PE? 8) What are the test characteristics of D-dimer for diagnosis of VTE?

Authors' results and conclusions: The search identified 64 original studies and 29 systematic reviews that addressed the questions. Results were as follows: 1) The evidence indicated that LMWH was more efficacious than UFH in reducing thrombus extension and recurrence in patients with DVT, with less risk of major bleeding and death. 2) Evidence was limited but supported the efficacy and safety of LMWH for the treatment of PE. 3) LMWH for outpatient treatment of DVT was safe and effective in carefully selected patients. LMWH was either cost-saving or cost-effective compared with inpatient treatment with UFH. 4) The evidence indicated that the optimal duration of oral anticoagulation after a first DVT is between three and six months. A longer duration may be necessary for patients with thrombophilic risk factors or PE. 5) Clinical prediction rules had high negative predictive values for excluding DVT, and moderately high predictive values for excluding PE. 6) Ultrasonography had high sensitivity and specificity for diagnosing proximal DVT, but was less accurate for diagnosis of calf vein thrombosis. 7) Helical CT was fairly sensitive and had high specificity for detecting PE. MRA was accurate in detecting PE of the lobar and segmental branches of pulmonary arteries. 8) The literature was too varied to make conclusions about the accuracy and role of D-dimer for diagnosis or exclusion of VTE.

Authors' recommendations: Relatively strong evidence exists to support the efficacy, safety, and cost-effectiveness of LMWH for treatment of DVT, as an inpatient or outpatient therapy. Moderate evidence exists to define the optimal duration of oral anticoagulation for patients with DVT. Less evidence exists regarding duration of treatment for PE. Strong evidence indicates that ultrasonography is accurate for diagnosing proximal DVT, while moderate evidence exists to support a role for clinical prediction rules for diagnosis of DVT or PE, and for helical CT or MRA for diagnosis of PE.

Authors' methods: Systematic review

Project Status: Completed

URL for project: http://www.ahrq.gov/clinic/tp/dvttp.htm

Year Published: 2003

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: Agency for Healthcare Research and Quality

Contact Address: Center for Outcomes and Evidence Technology Assessment Program, 540 Gaither Road, Rockville, MD 20850, USA. Tel: +1 301 427 1610; Fax: +1 301 427 1639;

Contact Name: martin.erlichman@ahrq.hhs.gov

Contact Email: martin.erlichman@ahrq.hhs.gov

Copyright: Agency for Healthcare Research and Quality (AHRQ)