Subcutaneous unfractionated heparin for the initial treatment of venous thromboembolism.

BACKGROUND: Venous thromboembolism is a prevalent condition with potentially dire consequences. Its medical treatment requires anticoagulation, which is usually achieved with either unfractionated or low molecular weight heparin (LMWH). Unfractionated heparin (UFH) is usually administered intravenously, but can be applied subcutaneously as well.

OBJECTIVES: To explore the effectiveness of subcutaneous UFH for the initial treatment of venous thromboembolism compared with other treatment modalities.

SEARCH STRATEGY: The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched 14 July 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched The Cochrane Library 2009, Issue 3). We searched MEDLINE and EMBASE (last searched February 2009).

SELECTION CRITERIA: Randomised controlled trials, in which treatment with subcutaneous UFH was compared to control, such as subcutaneous LMWH continuous intravenous UFH in patients with acute venous thromboembolism.

DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed trial quality.

MAIN RESULTS: Fifteen randomised controlled trials were included with a total of 3054 participants (1475 patients in the intervention group and 1579 patients in the control group). The results for all the major outcomes were statistically non-significant. The odds ratio (OR) for recurrent deep vein thrombosis (DVT) or pulmonary embolism (PE) during three months follow up were 1.68 (95% confidence interval (CI) 0.92 to 3.04) and 1.18. (95% CI 0.54 to 2.56), favouring the control arm. The odds ratio for developing PE during heparin treatment also favoured the control group (OR 1.10, 95% CI 0.46 to 2.62). The ORs for major bleeding during heparin treatment and throughout three months follow up were non significant (1.07, 95% CI 0.64 to 1.79, and 0.66, 95% CI 0.33 to 1.32, respectively). Disease or treatment related deaths as well as total mortality during heparin treatment and at three months follow up did not differ between study groups.

AUTHORS' CONCLUSIONS: Subcutaneous unfractionated heparin for the treatment of venous thromboembolism cannot be considered non-inferior to other treatment modalities in terms of recurrent DVT and PE at three months, but seems as safe and effective with regards to rates of major bleeding and death.