Low-molecular weight vs. unfractionated heparin for prevention of venous thromboembolism in general surgery: a meta-analysis.

To assess the association between low-molecular weight heparin (LMWH) and unfractionated heparin (UFH) in the prevention of venous thromboembolism (VTE) among participants undergoing general surgery. LMWH and UFH are the standard of practice in the prevention of VTE in surgery. However, in the context of general surgery, studies comparing the effectiveness of these treatments are limited. A systematic search was conducted to find studies which examined the comparative effectiveness between LMWH and UFH in the prophylaxis of VTE in the context of general surgery. The number of events of VTE in groups receiving LMWH or UFH was the primary outcome of interest, and was used to calculate odds-ratios. Amongst 33,068 participants pooled from twelve studies, the rate of VTE was 1.3% in those treated with LMWH, and 3.1% in those treated with UFH. Although there was a wide difference in rates due to clinical heterogeneity, there was no statistically significant difference between treatment effects [OR 0.77; 95% CI 0.58-1.03; p value = 0.0783; I2= 62.3%; 12 studies]. In terms of the sensitivity analysis, sources overly contributing to heterogeneity were removed. The random-effects model continued to show insignificance between LMWH and UFH in the prevention of VTE in participants undergoing general surgery [OR 0.86; 95% CI 0.69-1.08; p value = 0.2005; I2= 0%; 9 studies]. Results show an equal effectiveness in the prevention of VTE between participants undergoing general surgery in those allocated to receive LMWH to those allocated to receive UFH.