Sensitivity and Specificity of a Rapid Whole-Blood Assay for D-Dimer in the Diagnosis of Pulmonary Embolism

  1. Jeffrey S. Ginsberg, MD;
  2. Philip S. Wells, MD;
  3. Clive Kearon, MB;
  4. David Anderson, MD;
  5. Mark Crowther, MD;
  6. Jeffrey I. Weitz, MD;
  7. Janis Bormanis, MD;
  8. Patrick Brill-Edwards, MD;
  9. Alexander G. Turpie, MB;
  10. Betsy MacKinnon, MSc;
  11. Michael Gent, DSc; and
  12. Jack Hirsh, MD
  1. From McMaster University, Hamilton, Ontario, Canada; University of Ottawa, Ottawa, Ontario, Canada; and Dalhousie University, Halifax, Nova Scotia, Canada. Acknowledgment: The authors thank Agen Biomedical, Ltd., for donating the d-dimer assay kits. Grant Support: By grant MT-12016 from the Medical Research Council of Canada. Drs. Wells and Anderson are recipients of Research Scholarships from the Heart and Stroke Foundation of Canada. Drs. Ginsberg and Weitz are recipients of Career Investigator Awards from the Heart and Stroke Foundation of Ontario. Requests for Reprints: Jeffrey S. Ginsberg, MD, McMaster University Medical Centre, 1200 Main Street West, Room 3W15, Hamilton, Ontario L8N 3Z5, Canada. Current Author Addresses: Dr. Ginsberg: McMaster University Medical Centre, 1200 Main Street West, Room 3W15, Hamilton, Ontario L8N 3Z5, Canada.

    Abstract

    Background: Patients with suspected pulmonary embolism often have nondiagnostic lung scans and may present in circumstances where lung scanning is unavailable. Levels of d-dimer, a fibrin-specific product, are increased in patients with acute thrombosis; this may simplify the diagnosis of pulmonary embolism.

    Objective: To determine the sensitivity and specificity of a whole-blood d-dimer assay in patients with suspected pulmonary embolism and in subgroups of patients with low pretest probability of pulmonary embolism or nondiagnostic lung scans.

    Design: Prospective cohort.

    Setting: Four tertiary care hospitals.

    Patients: 1177 consecutive patients with suspected pulmonary embolism.

    Measurements: All patients underwent an assessment of pretest probability by use of a standardized clinical model, a d-dimer assay, ventilation-perfusion lung scanning, and bilateral compression ultrasonography. Patients in whom pulmonary embolism was not initially diagnosed were followed for 3 months. Accordingly, patients were categorized as positive or negative for pulmonary embolism.

    Results: Of the 1177 patients, 197 (17%) were classified as positive for pulmonary embolism. Overall, the d-dimer assay showed a sensitivity of 84.8% and a specificity of 68.4%. In 703 patients (3.4%) with a low pretest probability of pulmonary embolism, the likelihood ratio associated with a negative d-dimer test result was 0.27, resulting in a posterior probability of 1.0% (95% CI, 0.3% to 2.2%). In 698 patients with nondiagnostic lung scans (previous probability, 7.4%), the likelihood ratio associated with a negative d-dimer test result was 0.36, resulting in a posterior probability of 2.8% (CI, 1.4% to 4.8%).

    Conclusions: A normal d-dimer test result is useful in excluding pulmonary embolism in patients with a low pretest probability of pulmonary embolism or a nondiagnostic lung scan.

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    1. Ann Intern Med December 15, 1998 vol. 129 no. 12 1006-1011
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