CLINICAL UTILITY OF PROTHROMBIN FRAGMENT-1-III COMPLEXES AND D-DIMER MEASUREMENTS IN THE DIAGNOSIS OF DEEP-VEIN THROMBOSIS FOLLOWING TOTAL HIP-REPLACEMENT(2, THROMBIN ANTITHROMBIN)

Background: Measurements of prothrombin fragment 1+2 (F1+2), thrombin antithrombin III complexes (TAT) and D-dimer plasma levels have been p roposed as non-invasive screening tests to exclude postoperative deep venous thrombosis (DVT). We investigated the diagnostic efficacy of th ese coagulation activation markers to rule. out postoperative DVT in p atients undergoing hip surgery under antithrombotic prophylaxis. Metho ds: In this substudy of a randomized double-blind thrombosis prophylax is trial comparing three doses of desirudin (10, 15 or 20 mg b.i.d.) w ith unfractionated heparin (5000 IU t.i.d.) we used ELISA procedures t o measure F1+2, TAT and D-dimer in 159 patients undergoing total hip r eplacement at baseline (day 0) and on postoperative days 1, 3 and 6. B ilateral venography was performed in all cases 8-11 days after surgery . Results: For the F1+2 assay sensitivity ranged from 73 to 83% in the three postoperative days investigated, and negative predictive value (NPV) from 68 to 74%. For TAT and D-dimer sensitivity ranged from 71 t o 73% and from 71 to 83% and NPV from 61 to 65% and from 61 to 74% res pectively. Interpretation: In terms of sensitivity and NPV F1+2 and D- dimer are equivalent and are superior to TAT. However, their accuracy is too low to rule out the presence of DVT after hip surgery under ant ithrombotic prophylaxis.