BACKGROUND: Medication non-adherence is a common and costly problem. EU-wide, non-adherence may lead to almost 200,000 deaths and excess cost of €80–125 billion. Atrial fibrillation (AF) is the most frequent cardiac arrhythmia, increasing the risk of stroke from three to fivefold and being a leading cause of cerebrovascular mortality and morbidity. Oral anticoagulant medication is recommended to reduce this risk, but medication non-adherence leads to considerable health-risks and avoidable cost.

OBJECTIVES: To estimate the impact of medication non-adherence to direct oral anticoagulants (DOACs) compared to vitamin K antagonists (VKAs) in terms of clinical outcomes, direct medical cost, and cost-effectiveness.

METHODS: A previously published cost-effectiveness analysis (CEA) was used to assess the impact of medication non-adherence to DOACs compared to VKAs (Warfarin) for adult AF-patients using a lifetime horizon, a 5% discount rate, and an Austrian healthcare perspective. Real-world evidence on patient non-adherence and treatment discontinuation was identified through systematic review, integrated into the CEA, and varied in a series of deterministic sensitivity analyses to assess changes in incremental cost, health effects, and cost-effectiveness.

RESULTS: Apixaban is highly cost-effective compared to VKAs with an ICER of 12,891 EUR/QALY, and it dominates other DOACs. Assuming a WTP-threshold of 30,000 EUR/QALY, Apixaban is cost-effective at a 1^st year adherence rate of 38.6%. For other DOACs, respective adherence rates would have to range between 48.5%, and 76.3%. Improving medication adherence of Apixaban from 60% to 70% would prevent 1,155 AF-related health events versus VKAs and thus save €17.9 million in treatment cost in the eligible population (187,500 patients in Austria, based on prescription data).

CONCLUSIONS: Increasing medication adherence to DOACs results in better patient-related outcomes, higher life expectancy and improved health related quality of life. It also further improves the cost-effectiveness of DOACs for patients with AF in Austria.