Clinical effectiveness analisis of LMWH in the prevention of deep vein thrombosis and pulmonary embolism

Background: The aim of the study was to assess the clinical effectiveness of low molecular weight heparins in prevention of deep vein thrombosis and pulmonary embolism in comparison with physical methods, unfractionated heparin and placebo, by a systematic review of reports in medical literature. Methods: The assessment of the clinical effectiveness of undertaken interventions was compliant with the principles of systematic review (EBM), based on the Cochrane Collaboration guidelines. Statistical analysis and meta-analysis were performed by means of the RevMan 4.2 software version. Results: Regarding the risk of postoperative overall deep-vein thrombosis and proximal deep-vein thrombosis, a meta-analysis of obtained results revealed a trend towards low-molecular-weight heparin versus the results of physical methods. However, the difference between the analyzed groups did not reach statistical significance. Compared to placebo, the results of deep vein thrombosis risk assessment by meta-analysis showed statistically significant differences in favor of low-molecular-weight heparins (RR = 0.50, 95% CI: 0.34, 0.74, P = 0.0004, NNT = 23). In comparison to the group, receiving unfractionated heparin, the observed differences did not attain statistical significance, neither in thromboembolism prevention nor in deep vein thrombosis treatment. Regarding the risk of any bleeding episodes, the meta-analysis showed a statistically significant difference in favor of low-molecular-weight heparins administered in the study group vs. placebo results in the control group (RR = 1.55, 95% CI: 1.07, 2.24, P = 0.02) with the NNH equal to 94. Conclusion:Low molecular weight heparins are effective and safe treatment for venous thromboembolism versus placebo, however, no statistically significant advantages were observed vs. physical methods or unfractionated heparins.