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CME / CE

Guidelines Issued on Venous Thromboembolism Diagnosis and Management

  • Authors: News Author: Carole Bullock
    CME Author: Charles Vega, MD, FAAFP
  • CME / CE Released: 2/2/2007; Reviewed and Renewed: 2/1/2008
  • THIS ACTIVITY HAS EXPIRED
  • Valid for credit through: 2/1/2009
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Target Audience and Goal Statement

This article is intended for primary care clinicians, emergency medicine specialists, hematologists, radiologists, cardiologists, and other specialists who care for patients who may develop VTE.

The goal of this activity is to provide medical news to primary care clinicians and other healthcare professionals in order to enhance patient care.

Upon completion of this activity, participants will be able to:

  • Describe the clinical consequences of VTE.
  • Identify current best practices for diagnosing VTE.


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Medscape, LLC encourages Authors to identify investigational products or off-label uses of products regulated by the US Food and Drug Administration, at first mention and where appropriate in the content.


Author(s)

  • Carole Bullock

    Carole Bullock is a freelance journalist for Medscape. She has been writing and reporting on health and science news since 1980. She was the Senior Communications Manager for the American Heart Association for 9 years. Carole has a B.A. in Biology from the University of Texas and a M.A. in Journalism from New York University. She can be contacted at [email protected]

    Disclosures

    Disclosure: Carole Bullock has disclosed no relevant financial relationships.

CME Author(s)

  • Charles P Vega, MD

    Associate Professor; Residency Director, Department of Family Medicine, University of California, Irvine

    Disclosures

    Disclosure: Charles Vega, MD, FAAFP, has disclosed that he has received grants for educational activities from Pfizer.


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CME / CE

Guidelines Issued on Venous Thromboembolism Diagnosis and Management

Authors: News Author: Carole Bullock CME Author: Charles Vega, MD, FAAFPFaculty and Disclosures
THIS ACTIVITY HAS EXPIRED

CME / CE Released: 2/2/2007; Reviewed and Renewed: 2/1/2008

Valid for credit through: 2/1/2009

processing....

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

VTE affects an estimated 71 per 100,000 persons each year. Thrombosis of veins proximal to the knee increases the risk for PE, which can occur at rates of up to 70% in such patients. Patients with undiagnosed, untreated PE have a rate of a subsequent fatal embolic event of 26%, and another 26% may experience a recurrent nonfatal embolic event. Thrombosis confined to the veins inferior to the knee carries a lower risk for PE, but these thrombi are associated with high rates of postthrombotic syndrome.

The use of D-dimer testing and clinical prediction rules has altered the ways that clinicians diagnose VTE since the last report from the Evidence-Based Practice Center and American College of Physicians in 2003. The current guidelines offer the best practice in diagnosing VTE among ambulatory patients.

Study Highlights

  • The authors recommend the Wells prediction rules for VTE as a fairly reliable means to predict the risk for thrombotic events prior to diagnostic testing. However, they caution that these rules are most effective among young patients without a history of VTE or significant comorbidity.
  • Enzyme-linked immunosorbent assay and advanced turbidimetric D-dimer tests are associated with a sensitivity of diagnosing VTE between 96% and 100%. Specificity of this test is approximately 50% for VTE. Therefore, patients with a low clinical pretest probability of VTE and a negative D-dimer assay may not need to undergo further diagnostic testing to evaluate for VTE. Previous research has demonstrated that the 3-month incidence of VTE among such patients is 0.5%. Again, these criteria are most useful to exclude VTE among younger, healthier patients with a short duration of symptoms.
  • Patients with intermediate or high probability of VTE should undergo diagnostic imaging. Ultrasound is the test of choice to diagnose VTE of the lower extremities, with sensitivities of diagnosis between 89% and 96% and specificities from 94% to 99%. However, the sensitivity of ultrasound to diagnose thrombosis of calf veins is lower, ranging from approximately 75% among symptomatic patients to 50% among asymptomatic patients. Therefore, ultrasound cannot reliably exclude thrombosis in veins distal to the knee.
  • Patients with intermediate or high probability of PE should also undergo imaging studies. Helical computed tomography is frequently used as an initial imaging modality and carries a sensitivity of 90% and specificity of 95% compared with pulmonary arteriography in diagnosing PE. However, previous research has reported a wide range of accuracy of helical CT in diagnosing PE, meaning that this modality may not be sufficient to exclude the diagnosis. Meanwhile, research on modern multi-detector computed tomographic scanners has demonstrated 100% sensitivity in diagnosing PE compared with pulmonary arteriography. Overall, the accuracy of computed tomography in diagnosing PE appears to be improving, although the characteristics of a positive test result from multi-detector computed tomographic imaging are also evolving.

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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