The Lancet Publishes PREVAIL Study Results Showing LMW Heparin Superiority Over Unfractionated Heparin For Reducing The Risk Of Venous ThromboEmbolism

The PREVAIL (Prevention of VTE after Acute Ischemic Stroke with LMWH Enoxaparin) trial published in the medical journal The Lancet showed that once daily administration of enoxaparin sodium injection 40 mg was more effective than UnFractionated Heparin (UFH) 5000 IU twice a day for the prevention of VTE in patients who suffered an acute ischemic stroke, a group of medically- ill patients at an increased risk for developing VTE.

Among medically-ill patients, stroke patients are at an increased risk for developing VTE. Without VTE prophylaxis, up to 75% of patients with hemiplegia following stroke develop Deep-Vein Thrombosis (DVT) and 20% develop Pulmonary Embolism (PE).PREVAIL study showed a significant 43% relative risk reduction in VTE events was observed with enoxaparin sodium vs. unfractionated heparin (UFH) for the primary efficacy endpoint, the composite of symptomatic or asymptomatic DVT, symptomatic and/or fatal PE during the treatment period (10.2 % vs. 18.1%; p= 0.0001).Importantly, the reduction in VTE risk was also observed in patients presenting with different levels of ischemic stroke severity, without significant difference in clinically important bleedings as well.The significant reduction of VTE risk with enoxaparin sodium versus UFH was maintained when therapy was initiated within 24 hours or 24 hours-48 hours after stroke onset.The incidence of the composite of symptomatic intracranial and major extracranial haemorrhage was small with no difference between groups (enoxaparin 1.3%, UFH 0.7%; p=0.2275). No difference was observed for symptomatic intracranial haemorrhage between groups (0.5% vs 0.7%, respectively; p=0.5466). The rate of major extracranial bleeding, mainly gastrointestinal bleeding, was higher with enoxaparin (0.8% vs. %, p=0.0154) but did not lead to increased mortality. There was no difference in all-cause mortality between groups.In conclusion the authors said that “enoxaparin is preferable to unfractionated heparin for venous thromboembolism prophylaxis in this high- risk medically ill patient in view of its better clinical benefits to risk ratio and convenience of once daily administration.”(Source: The Lancet : PREVAIL Study Investigators : April 2007.)