Benefits now shown for extended thromboprophylaxis with
heparin
EXTENDED treatment with heparin for up to seven weeks
following total knee or hip replacement significantly reduces the frequency
of venous thromboembolism, say the authors of a meta-analysis of randomised
trials (Lancet 2001;358:9). The reduction in risk is equivalent
to preventing 20 symptomatic events and one death per 1,000 patients treated.
Nine studies involving 4,000 patients were included
in the analysis. The trials compared extended-duration heparin prophylaxis
with placebo or untreated controls. None of the studies assessed extended-duration
use of warfarin. The authors found that prophylaxis for 30 to 42 days
significantly reduced the frequency of symptomatic venous thromboembolism.
There was a greater risk reduction within the hip replacement group (1.4
per cent of patients treated with heparin experienced a symptomatic venous
thromboembolism compared with 4.3 per cent for placebo) than within the
knee replacement group (1.0 per cent compared with 1.4 per cent). Extended
treatment was associated with increased minor bleeding, but no increase
in major bleeding was noted. The authors comment that current international
guidelines state that seven to 10 days of thromboprophylaxis are adequate
and that it is common practice to treat for seven to 14 days after surgery
until discharge from hospital.
In a press release, one of the authors of the paper,
Dr Daniel Quinlan, department of radiology, King’s College Hospital, London,
said that there has been intense debate about the optimal duration of
thromboprophylaxis in these instances: “Our data provide clear evidence
that these patients benefit from extended duration thromboprophylaxis.”
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