Preferences for oral anticoagulants in atrial fibrillation: a best-best discrete choice experiment

Atrial fibrillation (AF) is recognised as a growing clinical and public health problem in many countries, owing to disability and death from stroke associated with the condition, high hospitalisation costs and an increasing prevalence with ageing populations. Under-treatment with oral anticoagulants has been a significant challenge of treatment, historically related to patient concerns over the safety and convenience of warfarin, which until recently was the only oral anticoagulant available.

The aim of this study is to examine: (1) patient preferences for attributes of warfarin and the new oral anticoagulants (dabigatran, rivaroxaban, apixaban) in AF; (2) which attributes are most important; and (3) whether current under-treatment is likely to improve with the new oral anticoagulants.

This study was conducted in Melbourne, Australia, with members of the general public with or without AF aged ≥40 years, where those without AF proxy for newly-diagnosed patients. Participants completed a computerised best-best discrete choice experiment (and follow-up interview) as if they had AF with a moderate-to-high risk of stroke. Choice data were modelled using mixed rank-ordered logit. Relative value was explored via estimation of marginal rates of substitution with predicted probability analysis used to simulate potential uptake of oral anticoagulants.

Seventy-six participants were recruited and completed the study. Efficacy (stroke risk) was more important than safety (bleed risk, antidote), which were both considerably more important than convenience factors (blood tests, dose frequency, drug or food interactions). Cost was also important. Predicted use of the new oral anticoagulants (and under-treatment of AF) using simulation, given moderate-to-high risk of stroke, is 25 % (52 %), 54 % (29 %) and 70 % (21 %) assuming a market price of AUD$120/month, AUD$30/month (subsidised price) and AUD$30/month with an antidote, respectively.

Based on the study sample and the modelled attributes, the overall profiles of the new oral anticoagulants were preferred to warfarin as their cost decreased. Public subsidisation and the development of antidotes (such as vitamin K for warfarin) for the new oral anticoagulants may have a positive effect on the under-treatment of AF.