TOPLINE:

Among Medicare beneficiaries with atrial fibrillation, the first prescription of an oral anticoagulant was not associated with a reduced risk for ischemic stroke but increased risks for major bleeding and intracerebral and major gastrointestinal hemorrhage.

METHODOLOGY:

• Researchers conducted a retrospective observational cohort study to determine whether the first prescription of an oral anticoagulant was associated with a reduced risk for ischemic stroke in older patients with atrial fibrillation.
• Data of 144,969 Medicare beneficiaries aged 66 years or older (60.8% women) with atrial fibrillation from 2007 to 2020 were analyzed; the mean follow-up duration was 3.46 years.
• Of these participants, 65,656 initiated an oral anticoagulant (warfarin, apixaban, rivaroxaban, dabigatran, or edoxaban), and 79,313 participants did not initiate anticoagulant treatment.
• The primary effectiveness endpoint was a composite of cerebral or retinal ischemic stroke; the safety endpoint was any major bleeding event.

TAKEAWAY:

• First prescription of an oral anticoagulant was not associated with a reduction in the risk for ischemic stroke in an overlap weighted analysis (adjusted hazard ratio [aHR], 1.01; 95% CI, 0.97-1.05).
• Initiation of anticoagulant was associated with increased risks for major bleeding events (aHR, 1.33; 95% CI, 1.31-1.35), intracerebral hemorrhage (aHR, 1.22; 95% CI, 1.17-1.26), and major gastrointestinal hemorrhage (aHR, 1.26; 95% CI, 1.23-1.28).
• Patients who received their first prescription of an anticoagulant had a reduced risk for all-cause mortality (aHR, 0.86; 95% CI, 0.85-0.88).

IN PRACTICE:

“These results suggest that, on average, clinicians treating patients with AF [atrial fibrillation] may need to take measures to promote not just initiation of anticoagulation but serum monitoring, lifestyle precautions (including attention to food and medication interactions), and control of background vascular risk factors,” the authors of the study wrote.

SOURCE:

The study was led by Jay B. Lusk, of the Department of Family Medicine at The University of North Carolina at Chapel Hill. It was published online on November 10, 2025, in the Journal of Internal Medicine.

LIMITATIONS:

The outcomes may not apply to younger populations. The analysis examined only initiation of anticoagulant defined by first prescription fill, without accounting for adherence patterns. Certain clinical factors such as obesity, use of tobacco, extent of hyperlipidemia, or degree of hypertension may not have been measured in detail in the billing data used. 

DISCLOSURES:

This study was funded by the National Institutes of Health and Duke University Office of the Provost. Some authors disclosed receiving grants, institutional support, and consulting fees from or other having relationships with various pharmaceutical companies and institutions.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.