UK Study Assesses Oral Anticoagulants in Stroke Prevention

Although there are difference in how and to whom oral anticoagulants (OACs) are prescribed, researchers have found that those taking apixaban seem to have higher persistence rates.

A paper describing the study, conducted by Michelle Johnson, MSc, at OXON Epidemiology, and colleagues, was published in the journal BMJ Open recently.

Patients with non-valvular atrial fibrillation (NVAF) are generally prescribed vitamin K antagonists (VKAs), “however,” say the researchers, “these drugs have narrow therapeutic window that forces regular monitoring and dietary restrictions.” More recently, novel oral anticoagulants (NOACs) have been developed. In the UK, those approved for use in stroke prevention are dabigatran, rivaroxaban, apixaban, and edoxaban.

“The aim of this study is to provide real-world evidence on the early persistence of OAC use for stroke prevention in people with NVAF in a period where there were four OACs available for this indication,” say the authors. Additionally, they say they “describe the characteristics of people with NVAF who are newly prescribed OACs for stroke prevention, estimate OAC persistence rates and compare the persistence rates of the newly prescribed OACs in routine clinical practice in the UK.”

The researchers identified 13,089 patients who were OAC naive. VKAs were most frequently prescribed, with 78.1% of the study population receiving VKAs, followed by rivaroxaban at 12.1%, dabigatran at 5.7%, and apixaban at 4.1%. The authors say, “New use of VKA declined over time, while an increasing proportion of patients were started on rivaroxaban or apixaban during the study period.”

“Of the 13,089 OAC naive patients, persistence was assessed for 11,657 patients who had a sufficient amount of follow-up,” report the researchers. The overall rate of persistence was 62.5%, and they say, “around two-thirds of non-persistence was owing to discontinuation of therapy and one-third was owing to switch to another OAC.”

One of the interesting findings of the study was “Despite early patterns of persistence changing over time since OAC initiation, comparatively, patients prescribed apixaban showed improved persistence over rivaroxaban, dabigatran and VKAs,” according to the authors. Additionally, persistence was better among patients taking VKAs for the first 2 months, but then poorer than apixaban in the later months.

The researchers note that “reasons for better persistence cannot be established from this study,” and suggest that future studies, with longer timelines would be helpful. They conclude, “A larger study with longer follow-up of apixaban users is needed to support these findings and to investigate whether there are differences in the risk of adverse outcomes between OACs which could explain differences in persistence.”

Related Coverage:

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Apixaban versus Warfarin and Aspirin in AF Patients: Cost-Effectiveness for Stroke Prevention