June 06, 2017
3 min read

Direct oral anticoagulants may be underprescribed to patients with AF, high stroke risk

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Direct oral anticoagulants increased the use of oral anticoagulation in patients with atrial fibrillation, but many eligible patients have not been prescribed the therapy, according to a study in the Journal of the American College of Cardiology.

“We found the availability of direct oral anticoagulants, which are as effective as warfarin for reducing the rate of stroke in patients with [AF] and lack many of the disadvantages of warfarin, increased the rate of use of anticoagulation in patients at risk for stroke,” Lucas N. Marzec, MD, clinical cardiac electrophysiologist at the University of Colorado in Aurora and researcher at the Colorado Cardiovascular Outcomes Research Consortium in Aurora, said in an interview with Cardiology Today. “However, more than one-third of eligible patients are not on anticoagulation. Further, we found the strongest predictor of use of anticoagulation and of direct oral anticoagulants was the practice at which they were cared for.”

Patients with AF

Researchers analyzed data from 655,000 patients (mean age, 74 years; 54% men) from the PINNACLE registry who were aged 18 years or older with nonvalvular AF and a CHA2DS2-VASc score > 1. The study population represented 3,164,236 outpatient encounters.

Lucas N. Marzec, MD
Lucas N. Marzec

The primary outcome was the prescription of any oral anticoagulation, including apixaban (Eliquis, Bristol-Myers Squibb/Pfizer; n = 16,757), dabigatran (Pradaxa, Boehringer Ingelheim; n = 44,090), rivaroxaban (Xarelto, Janssen Pharmaceuticals; n = 44,394) and warfarin (n = 249,512). Secondary outcomes were prescription of any direct oral anticoagulants, such as rivaroxaban, dabigatran and apixaban, and of an individual direct oral anticoagulant.

During the study period from April 2008 to September 2014, overall oral anticoagulation use increased from 52.4% to 60.7% (P < .01). Use of any direct oral anticoagulant increased from 0% to 25.8% (P < .01), and patients using warfarin decreased from 52.4% to 34.8% (P < .01).

Those using direct oral anticoagulants often had dyslipidemia, higher systolic and diastolic BP and hypertension. Higher CHA2DS2-VASc scores were associated with increased use of overall oral anticoagulation (OR = 1.06 per unit increase in CHA2DS2-VASc score; 95% CI, 1.05-1.07). Lower rates of direct oral anticoagulant use in patients who received oral anticoagulation were associated with higher CHA2DS2-VASc scores (OR = 0.97; 95% CI, 0.96-0.98).

Practice differentiation

Researchers found that the use of any oral anticoagulation, any direct oral anticoagulant and individual direct oral anticoagulants significantly differed between practices. Eligible patients who used any oral anticoagulation ranged from 11% to 78.8% (median OR = 1.52; 95% CI, 1.45-1.57). The use of any direct oral anticoagulant ranged from 0% to 40.4% (median OR = 3.58; 95% CI, 3.05-4.13).

“Further work is needed to understand the patient, provider, practice and health system factors associated with underuse of [anticoagulation in patients with AF],” Marzec told Cardiology Today. “This work will inform strategies to improve rates of anticoagulation and reduce variation in use of anticoagulation to reduce death and disability due to stroke related to [AF].”

“Just as we did for MI care, we need a national, professional response to the underuse of evidence-based stroke prevention treatments in AF,” Eric D. Peterson, MD, MPH, professor of medicine and Sean D. Pokorney, MD, MBA, medical resident at Duke University School of Medicine, wrote in a related editorial. “Strong clinical trial evidence demonstrates the efficacy of [vitamin K antagonists] and [direct oral anticoagulants] for stroke prevention, and efforts now need to be focused on bringing evidence to practice. Combined and united, our profession should find ways of bridging the gap in AF stroke prevention care and improving the quality of care delivered to AF patients.” – by Darlene Dobkowski

Disclosure: Marzec reports no relevant financial disclosures. Peterson reports receiving research grants from Eli Lilly and Company, Genentech and Janssen Pharmaceuticals, and consultant/advisory board support from Boehringer Ingelheim, Bristol-Myers Squibb, Genentech, Janssen Pharmaceuticals and Pfizer. Pokorney reports receiving consulting support from Boston Scientific, Bristol-Myers Squibb and Medtronic, and research support from Boston Scientific, Bristol-Myers Squibb, Gilead and Janssen Pharmaceuticals. Please see the full study for a list of the other researchers’ relevant financial disclosures.