Efficacy and safety of Clivarin and other LMWHs in general surgery: a meta-analysis

Low molecular weight heparin (LMWH) represents the most recent significant development in antithrombotic therapy. A number of meta-analyses of randomized double-blind and open studies of thromboprophylaxis in surgery have been reported recently. Standardized approaches for the diagnosis of efficacy parameters (deep vein thrombosis (DVT) and pulmonary embolism (PE)) have been used in those studies. However, the assessment of safety has varied considerably. In none of these meta-analyses has a homogeneous marker of bleeding risk such as wound haematoma been analysed. In theory, the dose of heparin used should affect safety as well as efficacy. Therefore, we performed a meta-analysis in which the efficacy and an objective assessment of safety in relation to the dose of heparin administered. The dose was standardized relative to the recently established first International Standard for LMWH. On-line literature searches in Medline, EMBASE, Biosis and Ringdoc databases identified 16 randomly allocated trials, of LMWH vs UFH, of high level of methodology which were included in the meta-analysis. The incidence and odds ratios (OR) in relation to the administered dose for DVT and for wound haematoma were recorded. The cut-off point of 3,400 IU aXa was found to be the currently highest recommended dose of LMWH for prophylaxis of thromboembolism in general surgery. The analysis of efficacy (DVT) of all trials gave an OR of -0.79, CI 0.63-0.99. The safety analysis (wound haematoma) of all trials gave an OR 1.03, CI 0.84-1.27.(ABSTRACT TRUNCATED AT 250 WORDS)