Long-term adherence to direct acting oral anticoagulants and the influence of health beliefs after switching from vitamin-K antagonists: Findings from the Switching Study

John K Bartoli-Abdou,Jignesh P Patel,Bipin Vadher,Alison Brown,Lara N Roberts,Raj K Patel,Roopen Arya,Vivian Auyeung

doi:10.1016/j.thromres.2021.11.003

Abstract

AimsSwitching non-adherent patients prescribed anticoagulant treatment to a regime with less monitoring could lead to significant non-adherence. Health beliefs are known to influence medication adherence; however, the extent of this influence is unknown in patients switched from vitamin-K antagonists (VKAs) to direct oral anticoagulants (DOACs). This study aimed to determine adherence to long-term therapy in patients switched from VKAs to DOAC due to low time in therapeutic range (TTR) and if adherence is associated with health beliefs. MethodsThe Switching Study is a longitudinal observational cohort study following patients for at least 1-year. 254 patients anticoagulated with VKAs for stroke prevention in atrial fibrillation (AF) or secondary prevention of venous thromboembolism (VTE) and TTR < 50% were recruited from anticoagulation clinics at King's College Hospital, London, UK. All participants were switched to DOAC and had health beliefs measured at baseline with VKA, 1-month and 12-months after switching. ResultsOf the 220 patients who completed 12-month follow-up 39% had sub-optimal adherence measured by self-report. 23% were non-adherent according to prescriptions issued. Increasing concerns about anticoagulation over time relative to beliefs about necessity was associated with lower self-reported adherence (OR = 0.902 95%C.I: 0.836, 0.974; p = 0.008). At baseline, believing that medications in general were overused in healthcare was negatively associated with adherence to DOAC (β = −1.5, 95%C.I: −2.7, −0.3; p = 0.013). ConclusionsAlthough many patients who switched were adherent to therapy long-term, between 23 and 39% of patients exhibited sub-optimal adherence: these patients can be identified through their modifiable health beliefs at the time of switching.

Highlights

In chronic disease, non-adherence to medication is reported in up to 50% of patients [1], where adherence is defined as the extent to which patients take medications as prescribed by healthcare providers [2]
Research suggests that among patients anticoagulated with vitamin-K antagonists (VKAs) for stroke prevention in non-valvular atrial fibrillation (AF) and secondary prevention of venous thromboembolism (VTE), adherence is highly variable
The work demonstrates that among those who switch from VKA to direct oral anticoagulants (DOACs) due to low therapeutic range (TTR), adherence to DOACs is relatively high for the majority, but there is a sizeable group of up to 39% who are non-adherent

Summary

Introduction

Non-adherence to medication is reported in up to 50% of patients [1], where adherence is defined as the extent to which patients take medications as prescribed by healthcare providers [2]. Adherence to chronic anticoagulation therapy is no exception. Research suggests that among patients anticoagulated with vitamin-K antagonists (VKAs) for stroke prevention in non-valvular atrial fibrillation (AF) and secondary prevention of venous thromboembolism (VTE), adherence is highly variable. Some studies report 40% of patients are adherent while others claim over 90% of patients adhere to treatment [3,4,5,6]. Research assessing adherence to direct oral anticoagulants (DOACs) is variable. Adherence to DOACs may be high initially, this wanes over time [7,8,9,10,11,12]

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Results

Conclusion