Cost-effectiveness of apixaban for stroke prevention in non-valvular atrial fibrillation in Saudi Arabia

BACKGROUND: Apixaban, an oral anticoagulant for stroke and systemic embolism prevention in non-valvular atrial fibrillation (NVAF), was superior to warfarin in prevention of stroke and systemic embolism, bleeding outcomes and mortality (ARISTOTLE trial), and substantially reduced stroke risk, with no significant increase in major or intracranial bleeding risk versus aspirin (AVERROES trial). OBJECTIVE: Estimate cost-effectiveness of apixaban versus other anticoagulants for NVAF treatment in Saudi Arabia. DESIGN: Lifetime Markov model. SETTING: A published model was adapted from the United Kingdom (UK) to the Saudi Arabia setting. PATIENTS AND METHODS: The model enabled pairwise comparisons of apixaban against other anticoagulants, aspirin, and aspirin+clopidogrel. Apart from warfarin and aspirin, comparisons were indirect. Subpopulations included vitamin K antagonist (VKA) suitable and unsuitable patients. Medication and physician visit costs were from published lists. A cost ratio (0.533), from comparison of UK and Saudi physician visit costs, was applied to UK model inputs to estimate local event costs. Background life expectancy was from Saudi life tables. Model structure, treatment comparators, patient characteristics, event rates, and utilities were unchanged. Costs and health benefits were discounted by 3.5% annually. MAIN OUTCOME MEASURE: Incremental cost-effectiveness ratio of cost per quality-adjusted life-year (QALY) gained. SAMPLE SIZE: Model cohort of 1000 NVAF patients, for VKA suitable and VKA unsuitable populations. RESULTS: Apixaban was dominant versus warfarin (VKA suitable) and rivaroxaban (VKA suitable and unsuitable). Compared against dabigatran (110mg, 150 mg, 110/150mg), the cost/QALY gained for apixaban was $5166, $11 143, $10 849 (VKA suitable) and $5 157, $14 424, $14 134 (VKA unsuitable), respectively. Cost/QALY for apixaban versus aspirin and aspirin+clopidogrel was $14 805 and $5784 (VKA suitable); and $10 564 and $4203 (VKA unsuitable), respectively. Sensitivity analyses demonstrated consistency of findings across varying inputs. CONCLUSIONS: Apixaban was found to be cost-effective for stroke prevention among Saudi NVAF patients, when assessed using a US$20 000 willingness-to-pay threshold. LIMITATIONS: Lack of robust local clinical, cost and utility data for model inputs. Lack of head-to-head clinical trial data for rivaroxaban, dabigatran, and clopidogrel plus aspirin comparators. CONFLICT OF INTEREST: Study was funded by Pfizer Inc. and Bristol Myers-Squibb. KO, RS, SAK and AAA received salaries from their respective employers, but did not receive direct financial compensation for participation in or authorship of this study.