Review: low-molecular-weight heparin reduces recurrent venous thromboembolism better than unfractionated heparin.

and commentary also appear in ACP Journal Club. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . For correspondence: Professor M Prins, University of Maastricht, Maastricht, The Netherlands. [email protected] Source of funding: Scottish Executive UK. Commentary P revious meta-analyses comparing fixed dose LMWH with adjusted dose UFH for the treatment of acute VTE showed that LMWH reduces all cause mortality, and found trends for reduction of recurrent VTE and major bleeding. 2 The meta-analysis by van Dongen et al used a comprehensive search strategy and included the most recent RCTs (all done after 1990) and thus presents an aggregate of the most current evidence. Furthermore, the large sample size shows that the review had sufficient power to find differences in efficacy. Their analysis confirmed that LMWH confers a survival advantage and significantly reduces the incidence of major bleeding and recurrent VTE. Limitations include the use of trials that compared LMWH with subcutaneous UFH, which may have contributed to the finding of superiority of LMWH; lack of an analysis examining whether the superiority of LMWH is maintained when limited to trials examining patients treated with LMWH primarily at home; the combining of 8 different LMWH preparations; and the small number of trials examining symptomatic PE. Despite these limitations, the rigorous methodology and consistency of the results with those of previous analyses support the main findings of improved outcomes with LMWH. Although LMWH has previously been shown to be at least as safe and efficacious as UFH and to allow selected patients with DVT to be treated at home, many patients are still often hospitalised and treated with UFH. Potential barriers to home treatment with LMWH are medication cost, inconsistent availability of the medication from area pharmacies, patient education about self injection, and outpatient initiation of oral anticoagulation. Given the data showing that LMWH improves outcomes and provides the opportunity to avoid hospitalisation for many patients, it is time to overcome any remaining obstacles and adopt LMWH as the standard of care for appropriately selected patients with VTE. Andrew Dunn, MD Mount Sinai Medical Center New York, New York, USA 1 Gould MK, Dembitzer AD, Doyle RL, et al. Ann Intern Med 1999;130:800–9. 2 Dolovich LR, Ginsberg JS, Douketis JD, et al. Arch Intern Med 2000;160:181–8. 3 Aujesky DA, Cornuz J, Bosson JL, et al. Int J Qual Health Care 2004;16:193–200. Fixed dose subcutaneous low molecular weight heparin (LMWH) v adjusted dose unfractionated heparin (UFH) for acute venous thromboembolism* Outcomes Follow up Number of trials (n) Weighted event rates RRR (95% CI) NNT (CI) LMWH UFH Recurrent venous thrombo-embolism During treatment 15 (6060) 1.4% 2.4% 31% (2 to 51) 100 (100 to ‘) 3 months 13 (5831) 3.0% 5.0% 30% (11 to 46) 50 (34 to 100) 6 months 6 (2781) 3.7% 5.7% 31% (3 to 51) 50 (34 to ‘) 3–6 months 18 (8122) 3.4% 5.4% 31% (15 to 44) 50 (34 to 100) Major haemorrhage During treatment 19 (7124) 1.0% 2.0% 42% (16 to 60) 100 (100 to ‘) All cause mortality 3–6 months 18 (8054) 5.0% 6.0% 23% (7 to 36) 100 (50 to ‘) *Abbreviations defined in glossary; weighted event rates, RRR, NNT, and CI calculated from data in article using a fixed effect models. 80 THERAPEUTICS www.evidence-basedmedicine.com EBM Volume 10 June 2005 group.bmj.com on June 21, 2017 Published by http://ebm.bmj.com/ Downloaded from