from Heartwire — a professional news service of WebMD

February 2, 2007 — The American College of Physicians and American Academy of Family Physicians announced clinical practice guidelines for the diagnosis and management of venous thromboembolism (VTE), which claims more than 200,000 lives each year in the United States.

The guidelines, which are the first ever to be developed by the 2 physician groups, were released on January 29, and are published jointly in the Annals of Internal Medicine and Annals of Family Medicine.

"The purpose of the guidelines is to present recommendations, based on the current evidence, to clinicians to aid in the diagnosis and management of lower extremity deep vein thrombosis (DVT) and pulmonary embolism (PE)," according to lead author Amir Qaseem, MD, of the American College of Physicians in Philadelphia, Pennsylvania.

The guidelines are also meant to bring attention to an expanding population at risk, Dr. Qaseem said in an interview with heartwire .

DVT occurs when clots form in the legs. If pieces of these leg clots break off and travel to the lungs, a serious condition called PE can occur.

"The annual incidence of VTE in the U.S. is 600,000 cases, and it is increasing with the aging population. Undiagnosed and untreated PE can result in up to 25% mortality. Early diagnosis and treatment is very crucial to prevent mortality and morbidity associated with it," stressed Dr. Qaseem.

He said the new guidelines are meant to help clinicians understand the value and use of various diagnostic tools, such as D-dimer and ultrasound, and the significance of the clinical characteristics that are useful in identifying high-risk patients.

"Strong evidence supports the use prediction rules," he said. "Use of high-sensitivity D-dimer assay in patients who have a low-pretest probability of VTE has a high negative predictive value, and is highest in younger patients with a low-pretest probability and no associated co-morbidities."

There is strong evidence supporting the use of ultrasonongraphy for diagnosing proximal DVT in patients with intermediate-to-high risk of pretest probability; however, he noted that sensitivity is much lower in asymptomatic patients for detecting calf vein DVT.

Positive D-dimer Test May Indicate Need for Ultrasound

"The clinical prediction rules will help physicians determine risk categories. If patients are in low-to-intermediate risk, they should get the D-dimer test. If the test is positive, ultrasound may be indicated," Dr. Qaseem said in his interview with heartwire .

For management, Dr. Qaseem said low-molecular-weight heparin (LMWH) is indicated for DVT, as it is as effective as unfractionated heparin, especially for reducing morbidity and mortality during initial therapy. Outpatient therapy is safe and cost-effective to treat DVT (but is good only for the highly selected population and if good support services are in place).

The recommendations call for the use of compression stockings to prevent postphlebitic syndrome, and anticoagulation is important.

"Duration is dependent on risk factors: Three to six months for VTE secondary to transient risk factors, and for more than 12 months for recurrent VTE," Dr. Qaseem said.

Diagnostic Guideline Recommendations

• Validated clinical prediction rules should be used to estimate pretest probability of VTE, both DVT and PE, and for the basis of interpretation of subsequent tests. Validated clinical prediction rules should be used to estimate probability of VTE, DVT, and PE on the basis of subsequent tests. The Wells prediction rule for DVT is the standard and is based on clinical characteristics (cancer, recently bedridden, swollen leg or calf, edema). For PE, the clinical characteristics are previous embolism, elevated heart rates, and hemoptysis.
• In appropriately selected patients with low pretest probability of DVT or PE, obtaining a high-sensitivity D-dimer is a reasonable option, and if negative, indicates a low likelihood of VTE.
• Ultrasound is recommended for patients with intermediate-to-high pretest probability of DVT in the lower extremities.
• Patients with intermediate or high pretest probability of PE require diagnostic imaging studies.

Low-Molecular-Weight Heparin Preferred Over Unfractionated Heparin

The management guideline recommends

• LMWH, rather than unfractionated heparin, should be used whenever possible for the initial inpatient treatment of DVT. Either unfractionated heparin or LMWH are appropriate for the initial treatment of PE.
• Outpatient treatment of DVT, and possibly PE, with LMWH is safe and cost-effective for carefully selected patients and should be considered when required support services are in place.
• Compression stockings should be used routinely to prevent postthrombotic syndrome, beginning within a month of diagnosis of proximal DVT and continuing for at least 1 year after diagnosis.
• There is insufficient evidence to make specific recommendations for types of anticoagulation management of VTE in pregnant women.
• Anticoagulation should be for 3 to 6 months for VTE and for more than 12 months for recurrent VTE. While the appropriate duration of anticoagulation for idiopathic or recurrent VTE is not definitively known, there is evidence of benefit for extended-duration therapy.
• LMWH is safe and efficacious for the long-term treatment of VTE in selected patients (and may be preferable for patients with cancer).

Ann Fam Med. 2007;5:57-62.

Ann Intern Med. 2007;146:204-240.

The complete contents of Heartwire , a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.

Clinical Context

Pearls for Practice

• PE can occur in up to 70% of patients with venous thrombosis in veins proximal to the knee, but it is less commonly associated with more distal thrombosis. PE can lead to recurrent embolic events in more than half of undiagnosed and untreated patients.
• Young, healthy patients with a low clinical probability of VTE and a negative D-dimer assay may not require diagnostic imaging for suspected thrombosis.

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