AVERROES: Apixaban bleeding profile no worse than with aspirin
MedWire News: The risk for major or intracranial bleeding among atrial fibrillation (AF) patients taking the factor Xa inhibitor apixaban is much the same as among those taking aspirin, show the full results from the AVERROES trial.
As previously reported, patients taking apixaban had a 55% reduction in the risk for ischemic stroke or systemic embolism, which resulted in the early termination of the AVERROES (Apixaban Versus Acetylsalicylic acid to Prevent Strokes in AF Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment) trial after an average follow-up of 1.1 years.
A total of 5599 AF patients with at least one other stroke risk factor were randomly assigned to receive twice-daily apixaban 5 mg or aspirin 81-324 mg/day. About 65% of the aspirin group took an 81-mg dose, about a quarter took 162 mg daily, and the remainder took a 243- or 324-mg dose.
Nearly all patients were clinically eligible for warfarin treatment but were considered unsuitable to receive the drug, with about half having multiple reasons for unsuitability. The two predominant reasons were physicians believing that routine measurement of international normalized ratios could or would not be achieved (in 43%) and patients refusing to take the drug (up to 38%).
During follow-up, 44 patients in the apixaban group suffered major bleeding (1.4% per year) compared with 39 (1.2% per year) in the aspirin group. This equated to a nonsignificant 1.13-fold increase in bleeding risk among patients taking apixaban (95% confidence interval: 0.74-1.75).
Importantly, there was no increase in hemorrhagic stroke risk among patients taking apixaban, of whom 11 suffered intracranial bleeding, compared with 13 aspirin-treatment patients.
Major bleeding is the main drawback of warfarin therapy, with intracranial bleeding the most feared outcome. The current findings suggest that a "reduction of intracranial bleeding will be one of the most important benefits of the newer oral antithrombotic drugs over vitamin K antagonist therapy," say Stuart Connolly (Population Health Research Institute, Hamilton, Ontario, Canada) and colleagues.
The primary outcome, of stroke or systemic embolism, occurred in 51 patients taking apixaban (1.6% per year) versus 113 patients taking aspirin (3.7% per year), giving a highly significant 55% risk reduction for the apixaban group.
"The net clinical benefit of apixaban in these patients was therefore substantial," concludes the team in the New England Journal of Medicine.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Eleanor McDermid