OBJECTIVES

Direct oral anticoagulants (DOACs) have confirmed efficacy in preventing strokes in patients with non-valvular atrial fibrillation (NVAF). However, nonadherence is considered to result in significant avoidable morbidity. This analysis evaluated the cost-effectiveness of full adherence compared to varying levels of nonadherence. Also, the cost-effectiveness of an adherence-improving intervention was assessed.

METHODS

A cost-utility analysis was performed based on published data from the Stockholm Healthcare database of NVAF patients with a first stroke between 2011 and 2018. A Markov model estimated costs, morbidity and mortality related to the natural history of NVAF and the effects of DOAC treatment over a 20-year horizon, for a cohort of 77-year-old patients in the base-case. Adherence was defined by the medication possession ratio (MPR;<90% defining nonadherence). The primary outcomes were number of ischaemic strokes and the associated incremental cost-utility ratio (ICUR). Costs comprised of treatment and health state costs.

RESULTS

Hypothetical comparisons between 1,000 patient cohorts of varying nonadherence levels and full adherence (MPR>90%), predicted an additional number of strokes ranging from 117 (MPR 81% to 90%) to 866 (MPR <61%), and years of life lost ranging from 177 (MPR 81% to 90%) to 1,318 (MPR <61%) (discounted at 3%).

Weighted results were generated to reflect real-world settings by comparing 1,000-patient cohorts with different nonadherence distributions. There was a cost saving of €456,150 (SEK 4,639,407) and a 31 QALY-gain when improving the proportion of fully adherent patients by 5% (from 81% to 86%). The maximum cost of a putative adherence improving intervention per patient was €2,739 (SEK 27,861) with a willingness to pay of 750,000 SEK/QALY.

CONCLUSIONS :

This analysis suggests an increasing clinical and economic burden associated with worsening levels of DOAC nonadherence, and that incremental improvements in adherence can deliver cost savings. This is an important consideration for Swedish health policymakers planning quality improvement initiatives.