Deprescribing Aspirin for Warfarin Patients May Reduce Bleeding

September 22, 2022

Many patients receiving long-term warfarin are also taking aspirin, often unnecessarily. Stopping aspirin for these patients reduces bleeding complications without any apparent harm, a new study has shown.

"Many patients on anticoagulation are taking aspirin without a clear indication, which is putting them at an increased risk of bleeding without offering them any benefits," senior author Geoffrey D. Barnes, MD, University of Michigan, Ann Arbor, told | Medscape Cardiology.

"Our study shows that it is possible to implement an easy, systematic approach in anticoagulation clinics to identify individuals who may not need to be on aspirin and to deprescribe aspirin in these patients," he added.

The study was published online in JAMA Network Open on September 19.

Barnes explained that most people who are receiving long-term anticoagulation therapy generally don't need to be taking aspirin as well if they have not had a recent myocardial infarction (MI), stroke, or an acute cardiac procedure.

"Many people think aspirin is good for the heart and purchase it over the counter so are taking it without medical supervision. And many others have been recommended by a doctor to take aspirin at some time in the past ― maybe after an MI or stroke or stent placement ― but the decision to continue taking aspirin long term has never been reviewed," he noted.

For the current study, Barnes and his colleagues empowered healthcare staff at anticoagulation clinics to try to identify patients who were taking warfarin and were also taking aspirin without a clear indication. These patients were then evaluated by a clinician in a systematic approach, with the aim of stopping aspirin if it was confirmed that it was not needed.

The study was conducted at six outpatient anticoagulation clinics throughout Michigan. Each site used a tailored screening process to identify adults receiving warfarin for atrial fibrillation and/or venous thromboembolism and who were also receiving concomitant aspirin inappropriately.

Potential inappropriate aspirin use was assessed on the basis of a set of agreed-upon criteria. Patients who were targeted for review of their ongoing aspirin use were adults without a history of coronary artery disease, MI, any percutaneous coronary intervention, coronary artery bypass grafting, peripheral arterial disease, mechanical valve replacement, or use of left ventricular assist devices.

The aspirin deprescribing intervention took place in 2017–2018. Data on bleeding and ischemic events were compared before and after the intervention.

Before the study was started, there had already been a slight reduction in aspirin use, reflecting discussion in the medical literature, so data from a historical period of 2 to 8 years before the intervention were also analyzed.

Results showed that among 6738 patients treated with warfarin, aspirin use decreased slightly from a baseline mean use of 29.4% to 27.1% during the 24 months before the intervention. After the intervention, the decrease accelerated to 15.7% at a mean of 6.7 months.

In the primary analysis, the intervention was associated with a significant decrease in major bleeding events per month from 0.31% preintervention to 0.21% postintervention.

No change was observed in the mean percentage of patients having a thrombotic event from before the intervention to after the intervention (0.21% vs 0.24%).

In the secondary analysis, reducing aspirin use (starting 24 months before the intervention) was associated with decreases in the mean percentage of patients having any bleeding event (2.3% vs 1.5%), the mean percentage of patients having a major bleeding event (0.31% vs 0.25%), and the mean percentage of patients with an emergency department visit for bleeding (0.99% vs 0.67%). There was no change in the mean percentage of patients with a thrombotic event (0.20% vs 0.23%).

"These findings highlight the need for greater aspirin stewardship among patients receiving warfarin for anticoagulation," the researchers conclude. "Our successful intervention across multiple health systems, with different patient populations and clinical structures, could serve as a national model for reducing excess aspirin use," they add.

The authors say further research is needed to determine whether deprescribing aspirin for patients receiving direct oral anticoagulants (DOACs) is similarly effective. Further research is also needed to confirm the current study findings, ideally with a control group.

Barnes pointed out that a previous study has shown a higher rate of bleeding among patients taking both a DOAC and aspirin. "So, I believe the same approach would likely be beneficial in patients on DOACs.

"Guidelines are already recommending that if a patient has not had a recent acute event and are on anticoagulation, they probably should not be on aspirin as well. But this is guidance and not based on results from randomized trials. Our study provides real-world data in support of this recommendation," Barnes commented.

"Our take-home messages are that we should be assessing aspirin use in all patients, especially in those taking anticoagulants, and that patients who are on anticoagulants who are also taking aspirin should talk to the doctor to discuss whether they need to continue taking aspirin."

He noted that when the study began, approximately one third of patients who were taking warfarin were also taking aspirin without a clear indication. "That number has reduced slightly over the last couple of years, but it is still a sizable group where a systematic approach to deprescribing aspirin could be very beneficial," he said.

The study was funded by Blue Cross Blue Shield of Michigan. Barnes has received personal fees from Pfizer/Bristol Myers Squibb, Janssen, Acelis Connected Health, Abbott Vascular, and Boston Scientific; and grant funding from Boston Scientific to institution during the conduct of the study.

JAMA Netw Open Published online September 19, 2022. Full text

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