Summary
Objective. To compare efficacy, safety, and feasibility of adjusted- dose oral anticoagulants
(OAC) versus fixed-dose subcutaneous low molecular weight heparin (LMWH) for the prevention
of deep venous thrombosis (DVT) in patients who have undergone elective hip or knee
replacement.
Design. Multicentre, single blind randomised trial. OAC (acenocoumarol, target International
Normalised Ratio, 2.0-3.0) and LMWH (nadroparine, 60 aXa IU/kg once daily) were started
preoperatively and continued for 10 days. All outcome measures were adjudicated by
an independent committee unaware of treatment allocation.
Subjects. 672 consecutive patients scheduled for elective hip or knee replacement
surgery. All patients wore bilateral graduated compression stockings.
Main outcome measures. The endpoint for the assessment of efficacy was venography
confirmed DVT or confirmed symptomatic pulmonary embolism. The endpoint for the assesment
of safety was clinically important bleeding during study treatment or within 48 h
of the end of treatment.
Results. Among the 517 patients with interpretable venograms, 391 had a hip replacement
and 126 had a knee implant. DVT was demonstrated in 50 (20%) of 257 patients allocated
to OAC and 43 (17%) of 260 patients allocated to nadroparine (p = 0.45), for an absolute
difference in DVT incidence of 2.9% in favour of nadroparine (95% Cl, -3.7-9.5). Clinically
important bleeding occurred in eight (2.3%) of the 342 oral anticoagulant treated
patients and in five (1.5%) of the 330 nadroparine treated patients (p = 0.62), for
an absolute difference in favour of nadroparine of 0.8% (95% Cl, -1.3-2.9).
Conclusion. Patients who undergo major orthopaedic operations have a high risk of
venous thromboembolism. Once daily fixed-dose subcutaneous nadroparine is at least
as efficacious and safe as daily adjusted OAC for prophylaxis against DVT after hip
or knee implantation but is more simple to administer.
