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Diagnosing PE: Combining Clinical Probability and D-Dimer Testing

Patients with suspected pulmonary embolism who have a normal D-dimer concentration and a low clinical probability of PE can safely forego further testing.

A clinical decision rule that combines risk factors, symptoms, and signs to predict the probability that a patient has a pulmonary embolism (PE) was published in 1998 but has not been widely used. Since 1998, the D-dimer test has come to the forefront and has been well studied. Researchers from the Netherlands assessed whether combining these 2 tools could safely reduce testing for PE. They developed and evaluated a diagnostic strategy in a prospective study of 242 consecutive patients with suspected PE.

If the clinical decision rule predicted low probability and the D-dimer test was negative, the patient was considered not to have PE, and no further testing was conducted. If the D-dimer concentration was elevated or the decision rule indicated moderate or high probability, the patient also underwent ultrasound of the legs. If the ultrasound was positive, treatment for thromboembolism was started; if the ultrasound was negative, pulmonary angiography was performed.

Overall, 26% of patients had a low probability of PE and a negative D-dimer test. None of these patients died during the 3-month follow-up. Three patients returned to the hospital because of recurring symptoms and underwent further testing; all were negative for PE. Thus, the 3-month risk for venous thromboembolism among patients with a low probability and a normal D-dimer concentration was 0% (95% CI, 0%-6%).

Comment: These authors present a rational, low-cost, and reasonably rapid way for physicians to decide when to shout "stop" during the evaluation of patients with suspected PE. The decision rule could be presented automatically when the D-dimer test is ordered, thereby providing the clinician with the necessary information.

— J. Stephen Bohan, MS, MD, FACP, FACEP

Published in Journal Watch Emergency Medicine October 16, 2002

Citation(s):

Kruip MJHA et al. Use of a clinical decision rule in combination with D-dimer concentration in diagnostic workup of patients with suspected pulmonary embolism: A prospective management study. Arch Intern Med 2002 Jul 22; 162:1631-5.

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