Estimation of the effectiveness of apixaban in non valvular atrial fibrillation in anticoagulant suitable population in Argentina

Abstract

Purpose: To estimate the effectiveness of apixaban relative to warfarin in NVAF anticoagulation suitable population in Argentina. Methods: A literature review was undertaken to obtain epidemiological, clinical atrial fibrillation, and stroke data in Argentina. Data of interest was efficacy and safety of apixaban and warfarin, and quality of life in NVAF and stroke. Two Delphi Panels conformed by 6 and 7 experts representing the 3 main health subsectors (private, public and social security) were used to review and validate findings from published literature. All data were used to populate and adapt a global Excel based Markov decision tree cost-effectiveness model. Apixaban 5 mg BID and warfarin (5 mg QD, INR adjusted) were allocated into a simulated cohort of 1,000 patients per treatment group over a lifetime horizon. Utilities were derived from an EQ 5D questionnaire. The effectiveness findings from the analysis are reported. Results: In 2012, Argentinean population was estimated around 42,192,494 with 11.1% (4,699,166) over 65 years of age. Estimated NVAF prevalence in the group of 65 and older is 8% (375,933). Of this cohort, 79% (296,987) were suitable for the use of anticoagulants and the average estimated CHADS2 score of 2.2. We estimated that 49% of the warfarin treated patients had a mean time in target range (TTR) over 52%. According to the model, the NNT for stroke (ischemic or hemorrhagic) was 53. As compared to warfarin, apixaban was estimated to avoid 13 strokes (ischemic and hemorrhagic) or systemic embolism events for every 1000 patients treated. Also, as compared to warfarin, apixaban was estimated to reduce 44 major bleeding episodes for every 1000 patients treated. Extrapolating these estimated strokes and bleeding risk reduction to the population at risk, apixaban would potentially avoid an additional 3861 strokes or systemic embolism events and an additional 13,067 major bleeding events. Compared with warfarin, apixaban would potentially increase 0.24 QALYs and 0.258 Life Years for every 1000 patients treated (71.3 QALYs and 76.6 years for the population at risk). Conclusion: Based on the model estimations, using epidemiological data from Argentina, the use of apixaban compared to warfarin in NVAF patients could reduce the burden of disease and related costs and improve patient's survival and quality of life by reducing stroke and major bleeding events.