US Cardiologists Are Underusing Oral Anticoagulation for A-fib

Increasing stroke risk scores are accompanied by a greater likelihood of receiving prescriptions for oral anticoagulation among US outpatients with A-fib, but the medications are still given to fewer than half of the highest-risk patients, a registry study shows.

The findings “should draw attention to a treatment gap in patients who may most appropriately need [oral anticoagulant] therapy,” write Jonathan Hsu, MD (University of California, San Diego), and colleagues in a paper published online March 16, 2016, ahead of print in JAMA Cardiology.

Although guidelines call for the use of risk scores to help guide clinicians on whether to give patients oral anticoagulation, it is not clear to what extent prescriptions increase as risk levels rise.

To explore the issue, the researchers turned to the American College of Cardiology’s National Cardiovascular Data Registry (NCDR) Practice Innovation and Clinical Excellence (PINNACLE) Registry. The analysis included 429,417 patients with A-fib enrolled at 144 practices in 38 states between 2008 and 2012. During the study period, the only commercially available oral anticoagulants were warfarin, dabigatran (Pradaxa; Boehringer Ingelheim), and rivaroxaban (Xarelto; Janssen Pharmaceuticals).

Overall, only 44.9% of patients were prescribed an oral anticoagulant, most commonly warfarin (90.3%). Another 25.9% received aspirin alone, 5.5% were given aspirin plus a thienopyridine, and 23.8% did not receive any antithrombotic therapy.

The mean CHADS₂ score was 2.0, and the mean CHA₂DS₂-VASc score was 3.7.

The likelihood of receiving oral anticoagulation versus no antithrombotic therapy increased with every 1-point rise in CHADS₂ score (adjusted OR 1.17; 95% CI 1.15-1.18) and CHA₂DS₂-VASc score (adjusted OR 1.19; 95% CI 1.18-1.20), with similar findings when the comparator was aspirin alone.

The rate of prescription of oral anticoagulation, however, did not top 50% even when the CHADS₂ score was over 3 and the CHA₂DS₂-VASc score exceeded 4.

Not a New Problem

Suboptimal use of oral anticoagulation has been seen in prior studies, the authors note.

But in the current study, “the lack of prescription of an [oral anticoagulant] by cardiovascular specialists in more than 50% of patients at the highest thromboembolic risk categories suggests that US cardiovascular healthcare professionals, who should be well versed in guideline-based therapy for [A-fib], may not fully appreciate the continued increased risk of thromboembolism with accumulation of additional stroke risk factors,” Hsu and colleagues write.

They say that the reason for an apparent plateau effect, in which the likelihood of prescription did not continue to increase at the highest risk levels, is unclear. But the plateau might reflect concerns about bleeding risk, despite the fact that the benefits of anticoagulation outweigh potential bleeding risks across risk levels, they add.

In an accompanying editorial, Jonathan Piccini Sr, MD (Duke University Medical Center, Durham, NC), and Gregg Fonarow, MD (University of California, Los Angeles), acknowledge that there remains room for improvement when it comes to using oral anticoagulation, even if some of the observed underuse could be explained by valid medical reasons that were not captured in the registry.

“Based on the data from the PINNACLE Registry, it seems that the more things have changed, the more they have stayed the same, despite recent advances in pharmacotherapy for stroke prevention,” they write.

They suggest multiple ways that the situation might be improved, including integration of reminders and decision support tools into electronic medical records, enhancement of patient education, and implementation of quality improvement efforts.

“One of the potential reasons for the lag in utilization of oral anticoagulation in [A-fib] relative to other cardiac drug therapies—for example, beta-blockers in heart failure or aspirin in acute coronary syndromes—is the relative paucity of formally endorsed [A-fib] quality measures being used for accountability and public reporting,” they say.

They point out that improvement in prescription rates was not seen over time among practices participating in the PINNACLE registry.

“Registries should provide healthcare professionals and health systems with timely feedback about treatment targets and performance that is actionable,” Piccini and Fonarow write. “Furthermore, performance improvement programs should be interactive, such that hospitals and outpatient practices use the data to change practice and achieve public recognition.”

Ultimately, they conclude, “the challenge going forward will be to ensure that the progress is universal and consistent.”

• Hsu JC, Maddox TM, Kennedy KF, et al. Oral anticoagulant therapy prescription in patients with atrial fibrillation across the spectrum of stroke risk: insights from the NCDR PINNACLE registry. JAMA Cardiol. 2016;Epub ahead of print.
• Piccini JP Sr., Fonarow GC. Preventing stroke in patients with atrial fibrillation—a steep climb away from achieving peak performance. JAMA Cardiol. 2016;Epub ahead of print.

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