This review summarizes the major clinical trials and addresses controversial areas such as extended (post-discharge) VTE prophylaxis and unfractionated versus low molecular weight heparin.
Pharmacologic VTE prophylaxis is associated with relative risk reductions for VTE in the neighborhood of 50-60%.
LMWH has a slight edge over UFH. Some studies were beset with design issues and had non statistically significant differences, but the signal consistently favored LMWH for efficacy with a suggestion of less bleeding risk.
While extended duration (post-discharge) VTE prophylaxis has been well validated for orthopedic and cancer surgery patients it is less well validated for medical patients. Benefits appear to be confined to particularly high risk patients at the price of increased bleeding risk.