The quality of evidence is downgraded by study limitations (unclear allocation concealment and selective outcome reporting).
A Cochrane review [Abstract] 1 included 29 studies with a total of 10 390 subjects. During the initial treatment period, the incidence of recurrent venous thromboembolic events was lower in participants treated with LMWH than in participants treated with unfractionated heparin (UFH; Peto OR 0.69, 95% CI 0.49 to 0.98; 18 studies, n=6 238). After a follow-up of 3 months, the period in most of the studies for which oral anticoagulant therapy was given, the incidence of recurrent VTE was lower in participants treated with LMWH than in participants with UFH (Peto OR 0.71, 95% CI 0.56 to 0.90; 16 studies, n=6 661), and at the end of follow-up, LMWH was associated with a lower rate of recurrent VTE than UFH (Peto OR 0.72, 95% CI 0.59 to 0.88; 22 studies, n=9 489). LMWH was also associated with a reduction in thrombus size compared to UFH (Peto OR 0.71, 95% CI 0.61 to 0.82, statistical heterogeneity I2 =56%; 16 studies, n=2 909). Major haemorrhages occurred less frequently in participants treated with LMWH than in those treated with UFH (Peto OR 0.69, 95% CI 0.50 to 0.95; 25 studies, n=8780). There was no difference in overall mortality between LMWH and UFH (Peto OR 0.84, 95% CI 0.70 to 1.01; 24 studies, n=9 663).
Primary/Secondary Keywords