Review: once daily LMWH is as effective as twice daily LMWH for initial treatment of venous thromboembolism.

Is once daily low molecular weight heparin (LMWH) as effective (for reducing recurrent venous thromboembolism [VTE]) and as safe (with respect to major haemorrhagic events) as twice daily LMWH in the initial treatment of VTE?METHODSData sources: Cochrane Peripheral Vascular Diseases Specialized Trials Register lup to April 2005), Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 1, 2005), Medline (up to April 2005), EMBASE/Excerpta Medica (up to April 2005), and bibliographies of relevant articles.Study selection and assessment randomised controlled trials (RCTs) in any language that compared (in an intention to treat analysis) once daily with twice daily use of a fixed dose of subcutaneous LMWH as initial treatment in patients with objectively documented WE (deep venous thromboembolism [DVT] or pulmonary embolism [PE]). Study quality was assessed using the laded scale. Trials without adequate concealment of allocation or without blinded outcome assessment were excluded.Outcomes: symptomatic recurrent VTE (DVT or PE) during initial treatment and during follow up; and major haemorrhagic episodes during initial treatment or within 48 hours after treatment cessation. Secondary outcomes included extension of thrombus size, all cause mortality, and post-thrombotic syndrome.MAIN RESULTS5 RCTs (n= 1508) met the selection criteria. 1 of the RCTs enrolled patients with DVT and PE, and the rest included only patients with DVT. Brands of LMWH included dalteparin, enoxaparin, nadroparin, and tinzaparin. In all RCTS, the same generic compounds were used in head to head comparisons of once and twice daily treatment regimens. Meta-analysis was done using a fixed effects model. Once daily and twice daily treatment regimens did not differ for any of the outcomes (table).CONCLUSIONOnce daily low molecular weight heparin (LMWH) is as effective (for reducing recurrent venous thromboembolism [VTE]) and as safe (with respect to major haemorrhagic events) as twice daily LMWH for initial treatment of patients with VTE.