Prospective study of the diagnostic accuracy of the simplify D-dimer assay for pulmonary embolism in emergency department patients

Jeffrey A. Kline, Michael S. Runyon, William B. Webb, Alan E. Jones, Alice M. Mitchell

Research output: Contribution to journalArticle

52 Scopus citations


Objective: To determine if a d-dimer assay (Simplify D-dimer; Agen Biomedical; Brisbane, Australia) can reliably exclude pulmonary embolism (PE) by producing a posttest probability of PE < 1% in low-risk, symptomatic emergency department (ED) patients. Methods: Hemodynamically stable patients were evaluated for PE using a structured d-dimer-centered protocol; d-dimer testing was performed prior to imaging. Prior to testing, physicians completed an electronic data form that included their unstructured clinical estimate for the pretest probability of PE (< 15%, 15 to 40%, or > 40%) and the elements of the Charlotte rule and Canadian score for PE. Criterion standard was selective use of pulmonary vascular imaging and 90-day follow-up. Results: We enrolled 2,302 patients (mean age, 45 ± 16 years [± SD]; 31% male); 108 patients received a diagnosis of PE (4.7%; 95% confidence interval [CI], 3.6 to 5.6%). The overall sensitivity and specificity of the d-dimer assay were 80.6% (95% CI, 71.8 to 87.5%) and 72.5% (95% CI, 70.6 to 74.4%), respectively. The negative likelihood ratio and negative predictive value were 0.27 (95% CI, 0.18 to 0.39) and 98.7% (95% CI, 98.0 to 99.1%), respectively. The posttest prevalence of PE among low-risk patients with negative d-dimer results was 0.7% (95% CI, 0.3 to 1.4%) for the unstructured estimate, 1.2% (95% CI, 0.7 to 2.0%) for the Canadian score, and 1.1% (95% CI, 0.6 to 1.7%) for the Charlotte rule. Conclusions: The Simplify D-dimer assay had moderate sensitivity and relatively high specificity for PE in low-risk ED patients. The combination of a physician's unstructured estimate of pretest probability of PE of < 15% and a negative d-dimer result produced a posttest probability of PE of 0.7% (95% CI, 0.3 to 1.4%).

Original languageEnglish (US)
Pages (from-to)1417-1423
Number of pages7
Issue number6
StatePublished - Jun 2006
Externally publishedYes


  • D-dimer
  • Diagnosis
  • Pulmonary embolism
  • Sensitivity and specificity
  • Thromboembolism

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine
  • Cardiology and Cardiovascular Medicine

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