• D-dimer;
  • deep vein thrombosis;
  • diagnosis;
  • diagnostic accuracy;
  • prospective study;
  • sensitivity;
  • specificity;
  • ultrasonography

Abstract. Larsen TB, Stoffersen E, Christensen CS, Laursen B (Aalborg Hospital, Aalborg, Denmark). Validity of D-dimer tests in the diagnosis of deep vein thrombosis: a prospective comparative study of three quantitative assays. J Intern Med 2002; 252: 36–40.

Objectives. To assess the diagnostic reliability of a new quantitative D-dimer assay (VIDAS New®) and an established quick test (Nycocard® D-dimer assay) in the diagnosis of deep vein thrombosis (DVT) compared with ultrasonography. A third assay (Auto Dimer®) became available during sample collection and has been included in the final assessment. The diagnostic performance of the Auto Dimer® assay was evaluated on three different coagulation analysers.

Design. A clinical prospective study of patients admitted to hospital for evaluation of DVT.

Setting. The admission ward at Aalborg Hospital.

Subjects. A total of 113 outpatients with suspected DVT.

Main outcome measures. Compression ultrasonography was used as the reference method for a diagnosis of DVT and compared with different D-dimer assays. The results were expressed as sensitivity, specificity, positive predictive value and negative predictive value (NPV).

Results. Deep vein thrombosis was established in 49 patients (43%). Two D-dimer assays (VIDAS New® and Auto Dimer®) showed sensitivities of 90 and 88%, specificities of 42 and 44%, and NPV's of 85 and 83%, respectively. The Nycocard® D-dimer assay showed a sensitivity of 63%, specificity of 67% and NPV of 71%.

Conclusions. The diagnostic performance of VIDAS New® and the Auto Dimer® D-dimer assays is almost identical, but this study suggests that neither of the D-dimer assays is suitable as the only screening method for DVT, in a situation with a high pretest probability of DVT. This call for a differential strategy that distinguishes between cases of low and high clinical probability using either a D-dimer test or ultrasonography.

Abbreviations DVT, deep venous thrombosis, NPV, negative predictive value, PPV, positive predictive value