Abstract
PurposeTo report the use of direct oral anticoagulants (DOACs) for stroke prevention in patients with atrial fibrillation in Scotland and advocate the standardisation of drug utilisation research methods.MethodsRetrospective cohort study using linked administrative data. Patients included those with a diagnosis of atrial fibrillation (confirmed in hospital) who received a first prescription for a DOAC (dabigatran, rivaroxaban, or apixaban) from September 2011 to June 2014. Drug utilisation measures included discontinuation, persistence, and adherence.ResultsA total of 5398 patients (mean CHA2DS2‐VASc score 2.98 [SD 1.71], 89.7% with ≥5 concomitant medicines) were treated with DOACs for a median of 228 days (interquartile range 105‐425). Of 35.6% who discontinued DOAC treatment, 11.0% switched to warfarin, and 48.3% reinitiated DOACs. Persistence after 12 and 18 months was 75.9% and 69.8%, respectively. Differences between individual DOACs were observed: Discontinuation rates ranged from 20.4% (apixaban) to 60.6% (dabigatran) and 12 months persistence from 60.1% (dabigatran) to 85.5% (apixaban). Adherence to treatment with all DOACs was good: Overall DOAC median medication refill adherence was 102.9% (interquartile range 88.9%‐115.5%), and 82.3% of patients had a medication refill adherence > 80%.ConclusionsIn Scotland, adherence to DOAC treatment was good, and switching from DOAC to warfarin was low. However, discontinuation and persistence rates were variable—although treatment interruptions were often temporary.To decrease the inconsistencies in drug utilisation methods and facilitate meaningful study comparison, the use of a coherent framework—using a combination of discontinuation, persistence, and adherence—and the standardisation of measurements is advocated.
Highlights
Parts of an earlier version of the paper's content have been presented as a poster at the International Conference on Pharmacoepidemiology and Therapeutic Risk Management in Dublin, August 2016.Drug utilisation research (DUR) is frequently conducted to analyse the use of drugs, and a core aspect is adherence to drug treatment, defined as the extent to which patients take drugs according to prescribingPharmacoepidemiol Drug Saf. 2017;1–9.wileyonlinelibrary.com/journal/pds MUELLER ET AL.instructions.[1]
Warfarin is used for multiple cardiovascular conditions, and high discontinuation rates of warfarin treatment have been reported in clinical trials and observational studies;[10,11,12] poor adherence has been ascribed to a variety of issues, from the occurrence of bleeding events to the inconvenience of treatment.[6,13,14,15]
The objective of this study is 2‐fold: first, to report on the use of direct oral anticoagulant (DOAC) for stroke prevention in patients with atrial fibrillation (AF) identified in Scottish secondary care; and second, to advocate the standardisation of DUR by applying an evolving methods approach, based on a sound theoretical framework and well‐documented measurements of adherence
Summary
Parts of an earlier version of the paper's content have been presented as a poster at the International Conference on Pharmacoepidemiology and Therapeutic Risk Management in Dublin, August 2016.Drug utilisation research (DUR) is frequently conducted to analyse the use of drugs, and a core aspect is adherence to drug treatment, defined as the extent to which patients take drugs according to prescribingPharmacoepidemiol Drug Saf. 2017;1–9.wileyonlinelibrary.com/journal/pds MUELLER ET AL.instructions.[1]. Treatment with DOACs follows easier dosing schemes and theoretically requires no monitoring, primarily because their therapeutic windows are wider and interactions with other drugs/foods are shown to be less than with warfarin.[18,19] Treatment with DOACs is deemed as effective and safe as with warfarin;[20,21,22,23] the effect of nonadherence on bleeding risk and stroke incidence among AF patients has been addressed but as yet not intensely studied.[24,25] Recently, concerns have been raised about the potential impact of no monitoring and the presence of multimorbidity and polypharmacy on DOAC adherence.[24,26,27,28,29] Knowledge about patients' adherence to DOACs in real life is still limited, and studies conducted far differ in scale, methodology, and focus.[25,30,31,32,33,34,35,36,37,38,39,40,41]
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