The performance of two rapid quantitative D-dimer assays in 287 patients with clinically suspected pulmonary embolism

Context: Objective tests are necessary for the diagnosis of pulmonary embolism (PE). D-dimer assays have been suggested as useful screening tests to exclude this diagnosis.

Objective: To compare the diagnostic accuracy of two rapid quantitative D-dimers in patients with suspected pulmonary embolism.

Design: Plasma D-dimer levels were measured using two commercially available assays (Tinaquant and Vidas). A strict imaging protocol was used to arrive at a final diagnosis of PE or deep venous thrombosis (DVT).

Setting: Multicenter study in six Dutch referral centers.

Patients: A total of 287 in- and outpatients with clinically suspected pulmonary embolism.

Main outcome measures: Diagnostic accuracy indices for the two assays were calculated and additional receiver-operated characteristics (ROC) analysis was performed.

Results: Using the manufacturer's advised cutoff values, the sensitivity and specificity were 88% and 52% for Vidas and 82% and 61% for Tinaquant, respectively. These differences were statistically significant (McNemar, P < 0.0001). However, no statistical differences were found between the two assays using ROC analysis (AUC = 0.78 for both assays).

Conclusions: Both quantitative D-dimer tests had similar diagnostic accuracy; however, at the manufacturer's advised cutoff level, Vidas performed significantly better. Nevertheless, to safely exclude pulmonary embolism, D-dimer assays should be combined with other diagnostic tests.