Summary

Background. The prevention of venous thromboembolic disease is lessstudied in medical patients than in surgery. Methods. We performed ameta-analysis of randomised trials studying prophylactic unfractionatedheparin (UFH) or low-molecular-weight heparin (LMWH) in internalmedicine, excluding acute myocardial infarction or ischaemic stroke. Deepveinthrombosis (DVT) systematically detected at the end of the treatmentperiod, clinical pulmonary embolism (PE), death and major bleeding wererecorded. Results. Seven trials comparing a prophylactic heparin treatmentto a control (15,095 patients) were selected. A significant decrease in DVTand in clinical PE were observed with heparins as compared to control (riskreductions = 56% and 58% respectively, p 0.001 in both cases), withoutsignificant difference in the incidence of major bleedings or deaths. Ninetrials comparing LMWH to UFH (4,669 patients) were also included. Nosignificant effect was observed on either DVT, clinical PE or mortality.However LMWH reduced by 52% the risk of major haemorrhage(p = 0.049). Conclusions. This meta-analysis, based on the pooling of dataavailable for several heparins, shows that heparins are beneficial in theprevention of venous thromboembolism in internal medicine.