title: Once versus twice daily LMWH for the initial treatment of venous thromboembolism.
abstract: BACKGROUND
  In the initial treatment of venous thromboembolism (VTE) low molecular weight heparin (LMWH) is administered once or twice daily. A once daily treatment regimen is more convenient for the patient and may optimise home treatment. However, it is not clear whether a once daily treatment regimen is as safe and effective as a twice daily treatment regimen.
  
  
  OBJECTIVE
  To compare the efficacy and safety of once daily versus twice daily administration of LMWH.
  
  
  METHODS
  We identified trials through searching the Specialised Register of the Cochrane Peripheral Vascular Diseases Group (last searched April 2005), the Cochrane Central Controlled Trials Register (CENTRAL) (last searched Issue 2, 2005), handsearches of relevant journals, checking cross-references and through personal communication with experts.
  
  
  METHODS
  Randomised clinical trials in which LMWH given once daily is compared to LMWH given twice daily for the initial treatment of venous thromboembolism.
  
  
  METHODS
  Two authors assessed trials for inclusion and extracted data independently.
  
  
  RESULTS
  Five studies were included with a total of 1508 participants. The pooled data showed a statistically non-significant difference in recurrent venous thromboembolism between the two treatment regimens (OR 0.82, 0.49 to 1.39). A comparison of major haemorrhagic events (OR 0.77, 0.40 to 1.45) and mortality (OR 1.14, 0.62 to 2.08) also showed a statistically non-significant difference between the two treatment regimens.
  
  
  CONCLUSIONS
  Once daily treatment with LMWH is as effective and safe as twice daily treatment with LMWH. However, the 95% confidence interval implies that there is a possibility that the risk of recurrent VTE might be higher when people are treated once daily. Hence, the decision to treat a person with a once daily regimen will depend on the evaluated balance between increased convenience and the potential for a lower efficacy.
authors: Department of Clinical Epidemiology and Biostatistics, Room J2-204, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, Netherlands. c.j.vandongen@amc.uva.nl
authors: C J
authors: CJ
authors: van Dongen
authors: M R
authors: MR
authors: MacGillavry
authors: M H
authors: MH
authors: Prins
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D006470:Hemorrhage / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage*; D006801:Humans; D011655:Pulmonary Embolism / Q000188:drug therapy; D016032:Randomized Controlled Trials as Topic; D013923:Thromboembolism / Q000188:drug therapy*; D020246:Venous Thrombosis / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight