Despite the increase in bleeding, patients appeared to benefit through overall reduction in stroke and systemic embolisms with net quality-adjusted life years gained of 0.185, 0.302, and 0.140 per patient treated with apixaban vs aspirin in the 3 cohorts, respectively.

“The ratio of the number of patients needed to treat to avoid an additional stroke over the number of patients needed to treat to harm with an additional bleed is estimated to be 0.5,” Gregory Lip, MD, of the Centre for Cardiovascular Science at the University of Birmingham in the United Kingdom, and his colleagues wrote in the study. “Therefore, 1 additional major bleed is caused for every 2 strokes avoided. Over a lifetime horizon, the net reduction in clinical events results in increased quality-adjusted life-year gains at marginal additional costs, deeming apixaban cost-effective vs aspirin across all low-risk patients.”


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The quality-adjusted life-year gains were achieved at an increased cost lower than the UK threshold of $44 400 per quality-adjusted life year gained across the 3 cohorts.

Although one might expect higher-risk patients to benefit more from this treatment than lower-risk patients, the researchers found that reduction in stroke and systemic embolism were higher in the lowest-risk group of participants with a CHA2DS2-VASc score of 1 vs a CHA2DS2-VASc score of 2 to 4, with a reduction of 84 strokes and systemic embolisms vs 34 strokes and systemic embolisms, respectively.

Researchers believe they found a larger reduction in strokes in the participants with a CHA2DS2-VASc score of 1  because they had lower all-cause mortality, leading to increased life expectancy and thereby an increased risk for stroke over a lifetime and because they had a higher risk reduction (though not statistically significant) compared with aspirin in stroke and systemic embolisms.

These findings demonstrate that treating patients at a low risk for stroke with an anticoagulant leads to increased life expectancy and provides cost-effective benefits. The researchers recommended that patients with a CHA2DS2-VASc score of 1 or greater be treated with anticoagulation.

Reference

Lip GYH, Lanitis T, Mardekian J, et al. Clinical and Economic Implications of Apixaban Versus Aspirin in the Low-Risk Nonvalvular Atrial Fibrillation Patients. Stroke. 2015;46:2830-2837.