Cost-effectiveness of apixaban compared to warfarin in the management of atrial fibrillation in Australia

Objective: To determine the cost-effectiveness of apixaban versus warfarin in patients with atrial fibrillation (AF) with a moderate to severe risk of stroke, from an Australian government-perspective. Methods: A decision-analytic Markov model was constructed to assess the cost-effectiveness of apixaban versus warfarin, based on data from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in AF (ARISTOTLE) trial. The model comprised five health states: Alive, no major bleeding or stroke, Alive, no major bleeding, post stroke/ systemic embolism, Alive, post major bleeding, no stroke, Alive, post-major bleeding and stroke and Dead. Disease cost data was derived from the North-East Melbourne Stroke Incidence Study and the Australian Refined Diagnose Related Groups. Costs of medications were based on data from the Pharmaceutical Benefit Scheme. Utility data was derived from published sources, and an annual discount rate of 5% was applied to costs and benefits. The main outcome of interest was incremental cost-effectiveness ratios per life year gained (LYG) and quality adjusted life years (QALYs) gained. Results: Over 20 years, in the sample of 1000 subjects the model predicted that compared to warfarin, apixaban led to a (discounted) of 0.33 LYG and 0.31 QALYs gained, at a net cost of $4,308 per-person. These equated to ICERs of $AUD12, 914 per LYG and $AUD13, 679 per QALY gained. Probabilistic sensitivity analysis demonstrated that apixaban was cost-effective at 99.0% probability using willingness to pay thresholds of $AUD45 000 per LYG and QALY. Conclusion: Compared to warfarin, apixaban is likely to represent a cost-effective means of preventing stroke-related morbidity and mortality in patients with AF.