Comparison of the clinical usefulness of two quantitative D-Dimer tests in patients with a low clinical probability of Pulmonary Embolism

Background: Quantitative D-Dimer tests are established methods in the non-invasive diagnostic management to rule out venous thromboembolism (VTE). The diagnostic performance and the clinical efficiency different D-Dimer assays in the exclusion of pulmonary embolism (PE) have not yet been compared in a clinical outcome study. Objective: Evaluation of the efficiency and safety of excluding the diagnosis of PE with two different quantitative D-Dimer assays in consecutive patients with clinically suspected PE. Patients and Methods: We studied the VTE-failure rate of 2206 consecutive patients with an unlikely clinical probability in whom VIDAS or Tinaquant D-Dimer tests were performed. Results: The prevalence of PE in 1238 patients whose D-Dimer level was analyzed with Tinaquant assay was 11%. The VIDAS assay group consisted of 968 patients with a PE prevalence of 13%. The VIDAS assay had a sensitivity of 99.2% (95%CI; 96 -> 99.9%), the Tinaquant assay of 97.3% (95%CI; 93-99%). The negative predictive value (NPV) in the Tinaquant assay group was 99.4% (95%CI 98-99.8%) in comparison to 99.7% (95%CI 99 -> 99.9%) in the VIDAS assay group. During 3 month of follow-up, there were no fatal cases of PE among patients with normal D-Dimer and unlikely clinical probability in both D-Dimer assay groups. In addition, the test efficiency of Tinaquant assay was significantly higher in comparison to VIDAS assay (52% vs 42%, p<0.001). Conclusion: Both Tinaquant and VIDAS D-Dimer tests perform equally well in combination with an unlikely clinical probability in excluding PE. The Tinaquant test was shown to be more efficient. (C) 2008 Elsevier Ltd. All rights reserved.