Forty-eight percent of atrial fibrillation (AF) patients, who are at the highest risk of stroke, were not prescribed oral anticoagulant (OAC) medication. That’s despite the incidence of stroke being seven times greater in these patients than in those without the condition.

The findings come from a new study by researchers at the University of California and published in JAMA Cardiology. They analyzed a cross-section of 429,417 outpatients with AF who were enrolled in the PINNACLE (Practice Innovation and Clinical Excellence) Registry between January 2008, and December 2012. The mean age of the participants was 71.3 years.

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A total of 192,600 patients (44.9%) with AF were prescribed an OAC, with warfarin being the most commonly prescribed therapy (173,832 [90.3%]), followed by dabigatran (14,896 [7.7%]) and rivaroxaban (3,872 [2.0%]). Using the CHADS2 and CHA2DS2-VASc score, researchers found each 1-point increase in either score was associated with increased odds of OAC prescription (approximately 15% greater adjusted odds). However, when CHADS2 scores exceeded 3 or CHA2DS2-VASc scores exceeded 4, the patients were more often not prescribed an OAC, even when compared with lower-risk counterparts.

The authors hypothesized that reluctance on the part of the healthcare professionals to prescribe OACs to sicker patients may be due to concerns surrounding bleeding risks. Despite the heightened bleeding risk with higher HAS-BLED scores, the authors note that the benefits of anticoagulation continues to outweigh the risk as all of these scores increase.

The authors conclude that “these findings draw attention to important gaps in appropriate treatment of patients with AF at the highest risk of stroke and highlight opportunities to understand the reasons behind these gaps and insights to improve them.”

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