Cost-effectiveness of apixaban vs. current standard of care for stroke prevention in patients with atrial fibrillation

Abstract

Aims: Warfarin, a vitamin K antagonist (VKA), has been the standard of care for stroke prevention in patients with atrial fibrillation (AF). Aspirin is recommended for low-risk patients and those unsuitable for warfarin. Apixaban is an oral anticoagulant that has demonstrated better efficacy than warfarin and aspirin in the ARISTOTLE and AVERROES studies, respectively, and causes less bleeding than warfarin. We evaluated the potential cost-effectiveness of apixaban against warfarin and aspirin from the perspective of the UK payer perspective.

Results and methods: A lifetime Markov model was developed to evaluate the pharmacoeconomic impact of apixaban compared with warfarin and aspirin in VKA suitable and VKA unsuitable patients, respectively. Clinical events considered in the model include ischaemic stroke, haemorrhagic stroke, intracranial haemorrhage, other major bleed, clinically relevant non-major bleed, myocardial infarction, cardiovascular hospitalization and treatment discontinuations; data from the ARISTOTLE and AVERROES trials and published mortality rates and event-related utility rates were used in the model. Apixaban was projected to increase life expectancy and quality-adjusted life years (QALYs) compared with warfarin and aspirin. These gains were expected to be achieved at a drug acquisition-related cost increase over lifetime. The estimated incremental cost-effectiveness ratio was £11 909 and £7196 per QALY gained with apixaban compared with warfarin and aspirin, respectively. Sensitivity analyses indicated that results were robust to a wide range of inputs.

Conclusions: Based on randomized trial data, apixaban is a cost-effective alternative to warfarin and aspirin, in VKA suitable and VKA unsuitable patients with AF, respectively.

Keywords: Apixaban; Aspirin; Atrial fibrillation; Cost-effectiveness; Stroke prevention; Vitamin K antagonist.

© The Author 2014. Published by Oxford University Press on behalf of the European Society of Cardiology.

Figures

Figure 1

Schematic representation model. ASA, aspirin CRNM, clinically relevant non-major; ICH, intracranial haemorrhages; NVAF, non-valvular atrial fibrillation; AC, anticoagulant; IS, ischaemic stroke; HS, haemorrhagic stroke. ‘M’ represents a Markov process with 11 health states that are identical for each of the treatment options. All patients remain in the ‘NVAF’ state until one of stroke, bleed, SE, MI, treatment discontinuation, or death occurs. The transition probabilities of these events depend on the treatment. For patients on second-line aspirin ‘NVAF subsequent ASA’ the events are identical however patients cannot experience any further discontinuation. Triangles indicate which health state the patient enters after an event. Health states coloured in blue are permanent health states, with the remainder being transient health states occurring for a maximum period of 6 weeks before returning to the prior or subsequent health state.

Figure 2

(A) One-way sensitivity analysis of apixaban vs. warfarin. (B) One-way sensitivity analysis of apixaban vs. aspirin. Rates are displayed per 100 patient-years. The solid vertical line represents the base–case incremental incremental cost-effectiveness ratio for apixaban compared with warfarin or aspirin. Horizontal bars indicate the range of incremental incremental cost-effectiveness ratios obtained by setting each variable to the values shown in the white boxes while holding all other values constant.

Figure 3

(A) Probabilistic sensitivity analyses for apixaban vs. warfarin. (B) Probabilistic sensitivity analyses for apixaban vs. aspirin. Each line represents a cost-effectiveness threshold representing the maximum amount society is willing to pay for a QALY gain. Apixaban is a cost-effective alternative in cases that fall to the right of this line; apixaban is not a cost-effective alternative in cases that fall to the left of this line.