Clinical trials with low molecular weight heparins in the prevention of postoperative thromboembolic complications: a meta-analysis.

Several clinical studies have evaluated the efficacy and safety of LMWH in the prevention of postoperative thromboembolic complications. We subjected 42 studies to a statistical meta-analysis in order to evaluate the efficacy of different prophylactic regimens compared with LMWH prophylaxis. In general surgery LMWH was more effective than LDH three times daily and placebo, but comparable with LDH twice daily. In elective hip surgery, thromboprophylaxis with LMWH was more effective than placebo, LDH, and dextran 70, but comparable with LDH in combination with dihydroergotamine. In patients undergoing surgery for hip fractures LMWH was more effective than placebo, but the studies comparing LMWH with LDH were too small to show any clinically relevant difference, although there was a trend toward a better efficacy of LMWH. This study demonstrated that LMWH is clinically effective and safe to use in the prevention of thromboembolic complications after general and orthopedic surgery.