Rapid D-dimer testing and pre-test clinical probability in the exclusion of deep venous thrombosis in symptomatic outpatients

We assessed the performance of three rapid D-dimer tests (Auto Dimertest(R) , VIDAS(R) and Tinaquant(R)) in combination with a pretest clinical probabi lity model for deep venous thrombosis (DVT) in 106 consecutive outpatients with suspected DVT. Contrast venography or colour-coded duplex ultrasonogra phy demonstrated the presence of DVT in 47 patients (14 distal DVT and 33 p roximal DVT). First, we assessed the accuracy indices for different cut-off levels of the rapid D-dimer tests. Sensitivity was found to be 97.9-100%, negative predictive value (NPV) was 96.3-100%, and the exclusion rate was 2 4.5-31.1%. Next, the patients were grouped according to the pre-test clinic al probability model in categories with low, moderate or high probability. In patients with a low pre-test probability, DVT would have been directly r uled out and the patients would not have undergone further investigations. In patients with a moderate probability, D-dimer testing and, in the case o f a positive result, objective testing would have been performed and, in th e case of a negative result, they would have been ruled out of having DVT. Patients with high probability would directly have undergone objective test s for DVT. The combination with the pre-test clinical probability model imp roved the exclusion rate (43.5-44.6%), whereas sensitivity (97.5-100%) and NPV (97.6-100%) remained roughly unchanged. The combination of rapid D-dime r tests with a pre-test clinical probability model may help to reduce unnec essary work-up in patients with suspected DVT. Blood Coagul Fibrinolysis 12 :165-170 (C) 2001 Lippincott Williams & Wilkins.