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New Clinical Decision Strategy Effective for Excluding Pulmonary Embolism

The approach combines a modified Wells rule, D-dimer testing, and selective chest CT.

Various strategies for the management of pulmonary embolism have combined clinical decision rules, D-dimer testing, and chest computed tomography with contrast. In a cohort study from the Netherlands, the authors evaluated one such strategy that involved a simplified version of the Wells clinical decision rule.

Consecutive patients with clinically suspected PE who presented to 12 centers over a 2-year period were categorized according to the Wells rule into two groups: PE unlikely (Wells score 4) or PE likely (Wells score >4). All patients in the PE-unlikely group underwent D-dimer testing (VIDAS or Tinaquant). The diagnosis of PE was excluded in patients who had normal D-dimer results (500 ng/mL); they did not undergo CT or receive anticoagulants. Patients who had elevated D-dimer results and all patients in the PE-likely group underwent chest CT (multidetector in most cases). The main outcome measure was venous thromboembolism (VTE) at 3-month follow-up.

Of 3306 patients, 2206 (67%) were categorized as PE unlikely and 1100 as PE likely. Overall, PE was diagnosed by CT in 674 patients (20.4%). Of the 1028 patients in the PE-unlikely group who had negative D-dimer results, 5 (0.5%) had VTE (nonfatal PE in 4, deep vein thrombosis [DVT] in 1) during the 3-month follow-up period. Of the 1436 patients who had negative CT findings, 18 (1.3%) had VTE (nonfatal PE in 3, fatal PE in 7, and DVT in 8).

Comment: The key elements in a strategy like this are the sensitivity of the D-dimer test (the VIDAS assay is superior; some latex agglutination methods are inadequate), the attributes of the CT scanner (multidetector is best), and even the radiologist interpreting the study. Nevertheless, the approach used here is rational and safe. In prior studies that used the Wells rule, patients were categorized into three groups: low, moderate, and high risk. According to this study, adoption of a Wells-based two-group classification system (PE unlikely, PE likely) could increase the number of patients in whom PE can be excluded by about 50%. The modified rule is simpler, and its use is associated with low risk for subsequent fatal and nonfatal PE.

— John A. Marx, MD, FAAEM, FACEP

Published in Journal Watch Emergency Medicine March 28, 2006

Citation(s):

Writing Group for the Christopher Study Investigators. Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. JAMA 2006 Jan 11; 295:172-9.

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• Medline abstract (Free)

Hull RD. Diagnosing pulmonary embolism with improved certainty and simplicity. JAMA 2006 Jan 11; 295:213-5.

• Original article (Subscription may be required)
• Medline abstract (Free)