Cut-off values of D-dimer and soluble fibrin for prediction of deep vein thrombosis after orthopaedic surgery

Soluble fibrin (SF) and D-dimer are considered to be useful for the diagnosis of thrombosis; however, the efficacy of the diagnosis of deep vein thrombosis (DVT) after orthopaedic surgery by SF and D-dimer is still not well established. The present study was designed to evaluate the efficacy of SF and D-dimer in the diagnosis of DVT after orthopaedic surgery. The plasma concentrations of SF and D-dimer were measured in 99 patients following orthopaedic surgery. The plasma concentrations of D-dimer and SF in patients undergoing orthopaedic surgery were markedly high in comparison to healthy volunteers, and these markers were increased after surgery. The plasma concentrations of D-dimer were significantly higher in patients with DVT than in those without DVT at days 4, 7, 10 and 14, and those of SF were significantly higher in patients with DVT than in those without DVT at days 1, 4 and 14. A receiver operating characteristic (ROC) analysis of SF and D-dimer for diagnosis of DVT after surgery generated an ROC curve that showed SF to be better than D-dimer at day 1, while D-dimer was better than SF at day 4. In addition, less than 7.2 μg/ml of D-dimer or 3.6 μg/ml of SF at day 1 after surgery, or less than 7.0 μg/ml of D-dimer at day 4 excluded DVT. These findings suggest that the D-dimer and SF are useful for the diagnosis and exclusion of DVT after orthopaedic surgery.