Aspirin Instead of Oral Anticoagulant Prescription in Atrial Fibrillation Patients at Risk for Stroke
Key result
Aspirin alone is prescribed instead of oral anticoagulants in ~40% of moderate-to-high risk AF outpatients.
- n=294,642
Why the study?
Oral anticoagulation, rather than aspirin, is recommended for AF patients at moderate to high stroke risk, but factors associated with prescribing aspirin alone in real-world cardiology practices required examination.
What factors are associated with the prescription of aspirin alone compared with oral anticoagulation in atrial fibrillation patients at intermediate to high stroke risk?
Key Points
- To examine patient- and practice-level predictors of prescribing aspirin alone versus oral anticoagulation among outpatients with atrial fibrillation at moderate-to-high thromboembolic risk.
- Analyzed outpatients with atrial fibrillation enrolled in the American College of Cardiology PINNACLE registry between 2008 and 2012 across two risk cohorts: CHADS2 score ≥2 (N=210,380) and CHA2DS2-VASc score ≥2 (N=294,642).
- Evaluated the prevalence and predictors of aspirin alone versus oral anticoagulants (warfarin or non-vitamin K antagonist oral anticoagulants) using multivariable hierarchical modified Poisson regression models.
- Aspirin alone was prescribed to 38.2% (80,371/210,380) of patients with CHADS2 ≥2 and 40.2% (118,398/294,642) of patients with CHA2DS2-VASc ≥2, while oral anticoagulants were prescribed to 61.8% and 59.8%, respectively.
- Aspirin monotherapy was independently associated with hypertension, dyslipidemia, coronary artery disease, prior myocardial infarction, stable/unstable angina, recent coronary artery bypass graft, and peripheral arterial disease.
- Oral anticoagulant prescription was positively associated with male sex, higher body mass index, congestive heart failure, prior stroke or transient ischemic attack, and prior systemic embolism.
Study Design
Type
Cohort (n=294,642)
Multicenter
Yes
Structured PICO
What factors are associated with the prescription of aspirin alone compared with oral anticoagulation in atrial fibrillation patients at intermediate to high stroke risk?
P
Population
294,642 outpatients with atrial fibrillation and intermediate to high thromboembolic risk enrolled in the PINNACLE registry between 2008 and 2012.
E
Exposure
Aspirin alone
C
Comparator
Oral anticoagulation (warfarin or non-vitamin K antagonist OACs)
O
Outcome
Prevalence of aspirin alone versus oral anticoagulation prescription
Main Result
Absolute Event Rate: 40.2% vs 59.8%
More than one-third of real-world atrial fibrillation patients at moderate to high risk of stroke are inappropriately prescribed aspirin alone instead of guideline-recommended oral anticoagulation.
Discussion
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Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“Stroke prevention is critical to the management of AF patients. However, giving aspirin alone to this population may not be the best treatment therapy because it is either minimally effective or not effective at all and still comes with risks, such as intracranial hemorrhage. Our study results show a gap in the appropriate treatment of AF patients at risk for stroke. The findings also highlight the critical need for cardiology specialists to adhere to standardized recommendations regarding the use of oral blood thinners instead of aspirin.”
“Even the most knowledgeable physicians may find themselves in a bind when encountering a patient who needs antiplatelet drugs, such as aspirin, due to coronary disease and blood thinners for atrial fibrillation. While a large proportion of AF patients meeting the guideline indications for stroke prevention medications fail to receive them, a lack of sufficiently rigorous data regarding optimizing net clinical benefit among those with strong indications for both antiplatelet drugs and anticoagulants may in part be to blame.”
“It is concerning that the highly motivated, conscientious, and talented cardiologists working in quality-conscious institutions that contribute their data to the NCDR are not prescribing anti-coagulation in one-third of their qualifying patients, as defined by our guidelines.”
Implication
High aspirin-only rates in high-risk AF warrant practice audits; leaves open targeted interventions to boost OAC uptake.
Cite This Study
Hsu et al. (2016) conducted a cohort in Atrial fibrillation (n=294,642). Aspirin alone vs. Oral anticoagulation was evaluated on Prescription of aspirin alone versus oral anticoagulation. Among 294,642 outpatients with atrial fibrillation at moderate to high stroke risk, 40.2% were prescribed aspirin alone rather than oral anticoagulants.