Anticoagulation still inadequate for many AF patients

Coagulation

By Siobhan Calafiore

4 Jul 2024

Stroke risk management among high-risk patients with non-valvular atrial fibrillation has markedly improved over the last decade, but one quarter of patients don’t receive recommended anticoagulation treatment, an Australian study has found.

Sydney researchers obtained de-identified data of 337,964 patients, of whom 8696 (2.6%) had non-valvular AF, from 164 general practices between 2011 and 2019.

Most patients with AF (85.8%) had a high stroke risk, which was defined by a CHA2DS2XW-VA score of ≥ 2, and just over two-thirds (70%) had a current script for oral anticoagulation (OAC), the current guideline-recommended treatment.

Findings published in IJC Heart & Vasculature [link here] suggested one in five patients received antiplatelet agents (APAs) only, noting that European Society of Cardiology Guidelines in 2016 and CSANZ & NHF guidelines in 2018 recommended that APAs had no role in stroke risk reduction.

One in 10 patients did not have a current script for either treatment.

As for who was prescribed an OAC, 70% had co-morbidities related to increased stroke risk (congestive heart failure, hypertension, diabetes, vascular disease and previous stroke), just over half (52%) were male and most had hypertension.

Around one-quarter had diabetes (27%) and 15% had a prior stroke.

Time trends showed a significant rise in the proportion of high-risk patients managed on OACs, increasing from 56.7% in 2011 to 73.7% in 2019, while the proportion prescribed APAs declined from 31.1% to 14.0% over the same period. The trends persisted after adjusting for patient characteristics.

The proportion of patients with no current script for OACs or APAs remained consistent at around 12% over the study period.

For warfarin specifically, the proportion of patients with a script declined from 50.8% in 2011 to 20.8% in 2019. Alternatively, there was a sharp up-take of non-vitamin K antagonist oral anticoagulants (NOACs) – the recommended first-line agent – from 5.9% in 2011 rising to 52.9% in 2019 in line with new guidance.

The researchers said their findings demonstrated “marked improvements” in stroke risk management of patients with AF over a decade, but more than one quarter (26.3%) of patients were still not adequately anticoagulated at the end of the study.

They said improved stroke risk management among this group, including better clinician assessment of the patient’s stroke risk and addressing potential barriers such as bleeding risk, might lead to larger reductions in avoidable strokes.

“The results showed that neither patients’ age nor gender was associated with being managed by an OAC. Previous studies have shown that females and older patients with AF are less likely to receive adequate anticoagulation,” they said.

“Changes to therapies available and the guidelines over the period covered by this study may have contributed to these findings.”

Limitations included most participating practices being based in Greater Sydney, limiting generalisability of the findings, and the lack of inclusion of cardiologist prescriptions, meaning patients might have been incorrectly identified as receiving no treatment.

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