Anticoagulation for thrombosis prophylaxis in cancer patients with central venous catheters
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BACKGROUND: Central venous catheter (CVC) placement increases the risk of thrombosis in cancer patients. Thrombosis often necessitates the removal of the CVC, resulting in treatment delays and thrombosis related morbidity and mortality. OBJECTIVES: To evaluate the efficacy and safety of anticoagulation in reducing venous thromboembolic (VTE) events in cancer patients with CVC. SEARCH STRATEGY: A comprehensive search for studies of anticoagulation in cancer patients up to January 2006 was conducted in the following databases: The Cochrane Central Register of Controlled Trials ( CENTRAL), MEDLINE, EMBASE and ISI the Web of Science. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing unfractionated heparin (UFH), low molecular weight heparin (LMWH), vitamin K antagonists (VKA), fondaparinux or ximelagatran to no intervention or placebo in cancer patients with a CVC or comparing two different anticoagulants. DATA COLLECTION AND ANALYSIS: Data was extracted on methodological quality, patients, interventions and outcomes including all cause mortality (primary outcome), premature CVC removal, catheter-related infections, CVC site and non CVC site deep venous thrombosis (DVT), pulmonary embolism (PE), major and minor bleeding and thrombocytopenia. MAIN RESULTS: Of 3986 identified citations nine RCTs were included in the meta-analysis including one published as an abstract and one focusing on paediatric patients not included in the meta-analysis. None of these RCTs tested fondaparinux or ximelagatran. The use of heparin in cancer patients with CVC was associated with a trend towards a reduction in symptomatic DVT (Relative Risk (RR) = 0.43; 95% Confidence Interval (CI): 0.18 to 1.06), but the data did not show any statistically significant effect on mortality (RR = 0.74; 95% CI: 0.40 to 1.36), infection (RR = 0.91; 95% CI: 0.36 to 2.28), major bleeding (RR = 0.68; 95% CI: 0.10 to 4.78) or thrombocytopenia (RR = 0.85; 95% CI: 0.49 to 1.46). The effect warfarin on symptomatic DVT was not statistically significant (RR = 0.62; 95% CI: 0.30 to 1.27). When studies assessing different types of anticoagulants were pooled, symptomatic DVT rates were significantly reduced (RR = 0.56; 95% CI: 0.34 to 0.92). AUTHORS' CONCLUSIONS: Cancer patients with CVC considering anticoagulation, should consider the possible benefit of reduced incidence of thromboembolic complications with the burden and harms of anticoagulation. Future studies should be adequately powered and evaluate the effects of newer anticoagulants such as fondaparinux and ximelagatran in cancer patients with CVC.