The Evaluation of D-Dimer Levels for the Comparison of Fibrinogen and Fibrin Units Using Different D-Dimer Kits to Diagnose VTE

The cutoff values of D-dimer levels for diagnosing or predicting the occurrence of deep vein thrombosis (DVT) were evaluated in preoperative patients and compared to those in non-DVT patients. The levels of 8 different D-dimers were measured using the latex agglutination method or enzyme immunoassay before surgery in 262 orthopedic surgery patients to diagnose subclinical DVT or predict postoperative DVT. There were 15 patients with subclinical DVT and 47 with postoperative DVT, but 200 patients had no DVT at all. All 8 plasma D-dimer values were significantly higher in the patients with subclinical or postoperative DVT than in those without DVT or in healthy volunteers. There were differences in the cutoff values between the assays highly sensitive for low D-dimer levels and wild-range assays of D-dimers. Some D-dimer assays might therefore be more useful than others for diagnosing low levels of D-dimer. Although the measurement of D-dimer levels was useful for diagnosing subclinical DVT and predicting the risk of DVT, the cutoff values for the diagnosis or prediction of DVT varied. The cutoff values for the prediction of postoperative DVT were ≥1.7 µg/mL (D-dimer A-D) and ≥1.0 µg/mL (D-dimer E-H).