LOW-MOLECULAR-WEIGHT HEPARIN VERSUS WARFARIN IN THE PREVENTION OF RECURRENCES AFTER DEEP-VEIN THROMBOSIS

To evaluate the role of low-molecular weight heparin (LMWH) as an alte rnative to oral anticoagulants in the prevention of recurrent venous t hromboembolism, we compared in a randomized trial conventional warfari n treatment with a three-month course of enoxaparin 4000 anti-Xa units once a day subcutaneously. 187 patients with symptomatic deep-vein th rombosis (DVT), diagnosed by strain-gauge plethysmography plus D-dimer latex assay and confirmed by venography in most cases, were treated w ith full-dose subcutaneous heparin for ten days and then randomized to secondary prophylaxis. During the 3-month treatment period, 6 of the 93 patients who received LMWH (6%) and 4 of the 94 patients on warfari n (4%) had symptomatic recurrence of venous thromboembolism confirmed by objective testing (p = 0.5; 95% confidence interval [CI] for the di fference, -3% to 7%). Four patients in the LMWH group had bleeding com plications as compared with 12 in the warfarin group (p = 0.04; 95% CI for the difference, 4% to 14%). In the 9-month follow-up period, duri ng which 34 patients on warfarin prolonged treatment for other 3 month s and 14 up to one year, 10 patients in the enoxaparin group and 4 pat ients in the warfarin group suffered a documented recurrence of venous thromboembolism. Of these 14 late recurrences, just one occurred in p atients with postoperative DVT. After one year there were 16 recurrenc es (17%) in the LMWH group and 8 (9%) in the warfarin group (p = 0.07; 95% CI for the difference, 1% to 16%). These results confirm the pote ntial of LMWH as an alternative to oral anticoagulants in this setting , and suggest to evaluate in a prospective study a slightly higher dos e of enoxaparin in patients with postoperative DVT.