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Medicare database analysis, Apixaban associated with significantly lower risk of stroke or systemic embolism and lower rate of major bleeding compared to Warfarin

Findings from a real-world data analysis of the U.S. Medicare database comparing the risk of stroke or systemic embolism and rate of major bleeding among patients with non-valvular atrial fibrillation who were treated with direct oral anticoagulants versus Warfarin were presented at the American College of Cardiology’s ( ACC ) 66th Annual Scientific Session in Washington, D.C..
In the analysis, titled Effectiveness and Safety of Apixaban, Dabigatran, and Rivaroxaban Compared to Warfarin among Non-Valvular Atrial Fibrillation Patients in the U.S. Medicare Population, Apixaban ( Eliquis ) was associated with a significantly lower risk of stroke or systemic embolism and lower rate of major bleeding compared to Warfarin.

In this observational analysis, medical and pharmacy claims were evaluated from the U.S. Medicare fee-for-service database of non-valvular atrial fibrillation patients age 65 and older who were newly prescribed oral anticoagulation therapy between January 1, 2013, and December 31, 2014 ( n=186,132, following inclusion and exclusion criteria ).
The analysis included 41,606 patients treated with Apixaban or Warfarin ( 20,803 patients each in the Apixaban and Warfarin cohorts ), balanced according to select demographic and clinical characteristics.
The matched Apixaban-Warfarin cohorts, followed for a mean of 5.7 and 6.5 months, respectively, had a mean age of 78 years, a CHA2DS2-VASc score of 4.6 and 4.7, respectively, and a HAS-BLED score of 3.3.
CHA2DS2-VASc score is a method for estimating stroke risk in patients with atrial fibrillation, and HAS-BLED score helps to estimate risk of major bleeding in patients with atrial fibrillation.

Real-world data analyses cannot be used as stand-alone evidence to validate the efficacy and/or safety of a treatment. Observational real-world studies can only evaluate association and not causality.

Apixaban, in this analysis, was associated with a significantly lower risk of stroke or systemic embolism ( hazard ratio, HR=0.40, 95% CI: 0.31-0.53; p less than 0.0001 ) and lower rate of major bleeding ( HR=0.51, 95% CI: 0.44-0.58; p less than 0.0001 ) than patients treated with Warfarin.
The findings from the Apixaban-Warfarin cohort complement the results of the randomized phase 3 ARISTOTLE ( Apixaban for Reduction In Stroke and Other ThromboemboLic Events in Atrial Fibrillation ) trial.

In addition to the Apixaban cohort, this analysis of the U.S. Medicare database included cohorts comparing two other direct oral anticoagulants ( Rivaroxaban [ Xarelto ] and Dabigatran [ Pradaxa ] ) separately with Warfarin.
The analysis was conducted in patients age 65 and older with non-valvular atrial fibrillation who had not received an oral anticoagulant for at least one year.
Patients had to have continuous health plan enrollment with medical and pharmacy benefits for at least 12 months pre-index date.
Patients with evidence of valvular heart disease, transient atrial fibrillation, venous thromboembolism, valve replacement or surgery or indication of pregnancy 12 months prior to the index date were excluded.

Real-world data have the potential to supplement randomized clinical trial data by providing additional information about how a medicine performs in routine medical practice.
Real-world data analyses have several limitations. For example, the source and type of data used may limit the generalizability of the results and of the endpoints.
It is important to note that there are no head-to-head clinical trials comparing direct oral anticoagulants.

Apixaban is an oral selective factor Xa inhibitor. By inhibiting factor Xa, a key blood clotting protein, Apixaban decreases thrombin generation and blood clot formation. ( Xagena )

Source: Pfizer, 2017