Differences between patient-driven adherence to vitamin K antagonists and direct oral anticoagulants. Do few missed doses matter? ACO-MEMS Study

• Published in: Thrombosis research 2019-07, Vol.179, p.20-27
• Main Authors: Solla-Ruiz, Itziar, Villanueva-Benito, Iñaki, Paredes-Galán, Emilio, Salterain-González, Nahikari, Oria-González, Garazi, De La Cuesta-Arzamendi, Francisco, Querejeta-Iraola, Ramón
• Format: Article
• Language: English
• Subjects: Aged; Anticoagulant drugs; Anticoagulants - pharmacology; Anticoagulants - therapeutic use; Atrial Fibrillation; Cohort Studies; Female; Humans; INR; Male; MEMS; Prospective Studies; Treatment adherence; Vitamin K - antagonists & inhibitors
• ISSN: 0049-3848; 1879-2472
• DOI: 10.1016/j.thromres.2019.04.023

Lack of INR controls might affect the adherence to direct oral anticoagulants (DOAC). The vast majority of studies that addresses adherence to anticoagulants are retrospective and based on pharmacy refill data. Our aim was to compare the adherence between vitamin K antagonists (VKA) and DOAC and to analyze the clinical relevance of non-adherence. A prospective two-arm observational cohort study was performed in two Spanish public hospitals. Adherence was assessed by Medication Event Monitoring System. Relationship between adherence and events during follow-up and time in therapeutic range (TTR) in the VKA group were analyzed. 257 patients were included (132 DOAC and 125 VKA). Monitoring time was 120 days (101−133). Patients in VKA group showed higher taking adherence (97.9% vs. 95.8%) and less non-adherent patients of >5% and >10% of the doses, without differences in >20% of the doses. Taking adherence was strongly associated with TTR (AUC: 0.89, CI 95%: 0.81–0.97 of TTR for detection of non-adherent patients of >10% of doses). During a follow-up of 1.8 years (1.6–2) non-adherent patients of >5% of doses presented more thromboembolic events (HR 6.1, CI95% 1.3–28.1). Although adherence to oral anticoagulant therapy was excellent, it was higher to VKA than to DOAC. Time in therapeutic range was highly sensitive to few missed doses of AVK. Non-adherence of >5% of prescribed doses had high clinical relevance. •Lack of INR controls could affect adherence to direct oral anticoagulants (DOAC).•Medication Event Monitoring System was used to compare adherence between both anticoagulants.•Adherence was very high, slightly better to vitamin K antagonists than to DOAC.•Missing even a few doses was related to poor INR control and had high clinical relevance.