Value of thrombin-antithrombin III complexes in major orthopedic surgery: Relation to the onset of venous thromboembolism

This study evaluated (a) the possible changes of plasma levels of thrombin- antithrombin III complexes during hospitalization to predict venous thrombo embolism in patients undergoing elective total hip replacement and (b) the sensitivity and specificity of thrombin-antithrombin III complexes in the l ate incidence of deep vein thrombosis when these patients are discharged fr om the hospital. In 50 consecutive patients (18 men, mean age = 63 +/- 8 ye ars) a venous blood sample was obtained fi om each patient before surgery a nd postsurgery on days 5 +/- 2, 9 +/- 2, and 45 to evaluate the thrombin-an tithrombin III complexes by the enzyme-linked immunosorbent assay as a part of a larger surveillance program. Six of 50 patients developed deep Vein t hrombosis, diagnosed by phlebography on the 45th day postsurgery. From the day before until the ninth day after surgery, mean values of the thrombin-a ntithrombin III complexes increased to a greater extent in patients with de ep vein thrombosis than in those without, although the differences were not significant (from 14.8 +/- 11.2 ng/mL to 36.2 +/- 19.1 ng/mL in the former group and from 13.6 +/- 3.3 ng/mL to 22.4 +/- 5.1 ng/mL in the latter, p = NS). On the 45th day after surgery the mean value of the thrombin-antithro mbin III complexes reduced less in patients with deep vein thrombosis (up t o 9.9 +/- 1.9 ng/mL and to 25.2 +/- 17.2 ng/mL, respectively, p = NS). In a ddition, thrombin-antithrombin III complexes remained over the level reache d on the fifth day only in the patients who developed deep vein thrombosis. On the 45th day after surgery, thrombin-antithrombin III complexes exhibit ed a sensitivity of 17%, a specificity of 86%, and an accuracy of 78% in di fferentiating the presence and absence of deep vein thrombosis as compared with phlebopraphy. We conclude that after total hip replacement (a) serial measurement of the thrombin-antithrombin III complexes does not appear help ful in predicting venous thromboembolism during hospitalization, and (b) me asurement of thrombin-antithrombin III complexes has a low diagnostic accur acy in diagnosing delayed deep vein thrombosis. However, the greater and pe rsistent increase]of thrombin-antithrombin III complexes level in patients who developed deep vein thrombosis may deserve further investigations.