DIAGNOSTIC EFFICACY OF THE D-DIMER ASSAY IN DISSEMINATED INTRAVASCULAR COAGULATION (DIC)

The D-Dimer (D-D) assay for measuring cross-linked fibrin degradation products is now available for the clinical laboratory. We combined this assay with other tests to assess patients with diagnosed or suspected DIC. Also, a small group of patients (20) with deep venous thrombosis (DVT) were studied. The D-D test, antithrombin-III assay, FDP titer, fibrinopeptide-A level, protamine sulfate test, fibrinogen, prothrombin time, and activated partial thromboplastin time were used. The D-D test was abnormal in 93.7%, the AT-III level was abnormal in 87.5%, the fibrinopeptide-A level was abnormal in 89.5%, and the FDP titer was elevated in 83.7% of patients with DIC. When assessing patients found not to have confirmed DIC the D-D assay was abnormal in 20%, the AT-III level was abnormal in 6%, and the fibrinopeptide-A level was elevated in 13%. We conclude the D-Dimer assay to be a useful molecular marker of hemostasis in diagnosing DIC and this test will often discriminate between those patients with or without DIC, especially when used with the AT-III and fibrinopeptide-A assays. Of the battery of tests used in this study, the most useful, in descending order of efficacy, appear to be the D-dimer assay (93.7% abnormal), the fibrinopeptide-A titer (89.5% abnormal), the AT-III level (87.5% abnormal), and the FDP titer (83.7% abnormal). Of the global tests, the diagnostic efficacy of the prothrombin time activated partial thromboplastin time, and protamine sulfate test were no greater than chance and appear to be of little use in aiding in a diagnosis of DIC. Also, the D-Dimer assay is similar in cost to the FDP titer and is cost effective for the routine clinical laboratory.