Summary
To evaluate the role of low-molecular weight heparin (LMWH) as an alternative to oral
anticoagulants in the prevention of recurrent venous thromboembolism, we compared
in a randomized trial conventional warfarin treatment with a three-month course of
enoxaparin 4000 anti-Xa units once a day subcutaneously. 187 patients with symptomatic
deep-vein thrombosis (DVT), diagnosed by strain-gauge plethysmography plus D-dimer
latex assay and confirmed by venography in most cases, were treated with 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 warfarin (4%) had symptomatic recurrence of venous thromboembolism
confirmed by objective testing (p = 0.5; 95% confidence interval [Cl] for the difference,
-3% to 7%). Four patients in the LMWH group had bleeding complications as compared
with 12 in the warfarin group (p = 0.04; 95% Cl for the difference, 4% to 14%). In
the 9-month follow-up period, during which 34 patients on warfarin prolonged treatment
for other 3 months and 14 up to one year, 10 patients in the enoxaparin group and
4 patients in the warfarin group suffered a documented recurrence of venous thromboembolism.
Of these 14 late recurrences, just one occurred in patients with postoperative DVT.
After one year there were 16 recurrences (17%) in the LMWH group and 8 (9%) in the
warfarin group (p = 0.07; 95% Cl for the difference, 1% to 16%).
These results confirm the potential of LMWH as an alternative to oral anticoagulants
in this setting, and suggest to evaluate in a prospective study a slightly higher
dose of enoxaparin in patients with postoperative DVT.
