Lower rates of stroke, bleeding seen with apixaban compared to warfarin in Afib patients, regardless of risk profile

Apixaban (Eliquis), an investigational anticoagulant developed by Bristol-Myers Squibb and Pfizer, has lower rates of stroke, systemic embolism, and bleeding than warfarin in patients with atrial fibrillation, regardless of level of risk for these events, according a recent online analysis published October 2 in The Lancet.

Researchers from Duke University Medical Center and other institutions analyzed the ARISTOTLE trial results that were previously published, to assess how the outcomes differed for patients according to three risk scores that are used to predict the risk of stroke and bleeding (CHADS2 score, CHA2DS2VASc score, and HAS-BLED score).

Patients who were assigned to apixaban (n=9120) had significantly lower rates of stroke or system embolism, mortality, and bleeding than those treated with warfarin (n=9081) in the ARISTOTLE trial, regardless of CHADS2 score. Stroke or systemic embolism occurred in 44 patients (0.74%) with a CHADS2 score of 1 who were assigned to apixaban and 51 patients (0.87%) who received warfarin. Those with a CHADS2 score of 2 had a higher rate of stroke and systemic embolism (74 [1.24%] taking apixaban and 82 [1.37%] taking warfarin. Those with a CHADS2 score of 3 or higher had the highest rate of stroke or systemic embolism (94 [1.95%] on apixaban and 132 [2.80%] on warfarin. Similar trends were evident in terms of mortality and bleeding rates, the authors noted.

"Irrespective of CHADS2, CHA2DS2VASc, and HAS-BLED score, patients who received apixaban had less net clinical events, with lower rates of the composite of stroke, systemic embolism, ISTH major bleeding, and all-cause mortality, than did patients who received warfarin. These results were driven mainly by reductions in bleeding,"the authors wrote.

The researchers suggested that because the benefits of apixaban do not differ in patients according to the risk scores, the risk scoring systems being used might not be as relevant when tailoring apixaban treatment to individual patients than for patients receiving warfarin.

"Further improvement in the methods for risk stratification of both stroke and bleeding should help to advance personalized treatment with novel oral anticoagulants in patients with atrial fibrillation, particularly those at low risk," the authors concluded.

The analysis was funded by Bristol-Myers Squibb and Pfizer.