Clinical and Economic Implications of Apixaban Versus Aspirin in the Low-Risk Nonvalvular Atrial Fibrillation Patients

BACKGROUND AND PURPOSE: Although recommended by guidelines, the benefits of treating patients with atrial fibrillation with a low-stroke risk score, with aspirin or anticoagulants, have not been clearly established. With advent of safer non-vitamin K antagonist oral anticoagulant, we assessed the clinical and economic implications of 5 mg BID of apixaban versus aspirin among patients with a relative low risk of stroke as assessed using the CHADS2 (congestive heart failure, hypertension, age>75, diabetes mellitus, stroke/transient ischemic attack) and CHA2DS2-VASc (congestive heart failure, hypertension, age, diabetes mellitus, stroke/transient ischemic attack, vascular disease) stroke risk classification.

METHODS: A previously developed and validated Markov model was adapted. A secondary analysis of the Apixaban Versus Acetylsalicylic Acid to Prevent Stroke in Atrial Fibrillation Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment (AVERROES) study was conducted to estimate event rates in different low-risk cohorts by treatment. Three cohorts (n=1000) with a CHADS2 score of 1, CHA2DS2-VASc score of 1, and CHA2DS2-VASc of score 2 to 4 were simulated to assess the number of clinical events avoided in terms of strokes and major bleeds, as well as life years gained, quality-adjusted life years gained, costs, and incremental costs per quality-adjusted life year gained.

RESULTS: Apixaban was associated with fewer strokes and systemic embolism versus aspirin across all subgroups; however, it caused more major bleeding events. The reduction in systemic embolism offset the increase in major bleeding events leading to increased life expectancy and quality-adjusted life year gains, achieved at an increased cost that was lower than the UK threshold of $44 400 (ie, £30 000) per quality-adjusted life year gained across the 3 cohorts examined.

CONCLUSIONS: Anticoagulant treatment with apixaban versus aspirin in low-risk patients, as identified using CHADS2 or CHA2DS2-VASc, is projected to increase life expectancy and provide clinical benefits that are cost effective.