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Increased stroke risk scores linked with more oral anticoagulant prescriptions
Patients with atrial fibrillation who have higher CHADS2 and CHA2DS2-VASC scores are more likely to be prescribed oral anticoagulant therapy, according to new data from the PINNACLE registry.
Jonathan C. Hsu, MD, MAS, assistant clinical professor in the section of cardiac electrophysiology at the University of California, San Diego, and colleagues performed a cross-sectional registry study of 449,417 patients with AF who were enrolled in the American College of Cardiology National Cardiovascular Data Registry’s (NCDR) PINNACLE registry (2008-2012). The mean age of the patients was 71 years. The researchers calculated CHADS2 and CHA2DS2-VASC scores for each patient to determine stroke risk.
The primary outcome was oral anticoagulant prescription, including warfarin, dabigatran (Pradaxa, Boehringer Ingelheim) or rivaroxaban (Xarelto, Janssen). Apixaban (Eliquis, Bristol-Myers Squibb/Pfizer) and edoxaban (Savaysa, Daiichi Sankyo) were not included because they had not yet been approved by the FDA at the time of the study.
The overall mean CHADS2 score was 2 and the mean CHA2DS2-VASC score was 3.7.
Forty-four percent of patients with AF received a prescription for oral anticoagulant therapy. Warfarin was prescribed in 90%, dabigatran in 7.7% and rivaroxaban in 2%). Overall, 25.9% of patients were prescribed only aspirin, 5.5% were prescribed aspirin plus dual antiplatelet therapy and 23.8% were prescribed no antithrombotic therapy.
For each 1-point increase in CHADS2 and CHA2DS2-VASC scores, the odds of oral anticoagulant prescription and antiplatelet therapy increased, according to unadjusted and multivariable-adjusted analyses. Each 1-point increase in CHADS2 score was associated with a 16.6% greater odds for oral anticoagulant therapy prescription compared with no antithrombotic therapy prescription (adjusted OR = 1.166; 95% CI, 1.152-1.18) and 15.8% greater odds compared with prescription of aspirin only (adjusted OR = 1.158; 95% CI, 1.144-1.172). Each 1-point increase in CHA2DS2-VASC score was associated with a 19% greater odds for oral anticoagulant therapy prescription compared with no antithrombotic therapy prescription (adjusted OR = 1.19; 95% CI, 1.184-1.196) and 16.3% greater odds compared with prescription of aspirin only (adjusted OR = 1.163; 95% CI, 1.157-1.169).
“Overall, there appeared to be a plateau effect of oral anticoagulant prescription across the spectrum of stroke risk because patients with a CHADS2 score exceeding 3 or a CHA2DS2-VASC score exceeding 4 were not often prescribed an oral anticoagulant even when compared with their lower-risk counterparts, and oral anticoagulant prescription did not exceed 50% in these highest-risk patients,” Hsu and colleagues wrote. “Our findings have important implications for patients with AF, particularly because annual stroke risk increases with the number of stroke risk factors measured by the CHADS2 score and the CHA2DS2-VASC score.”
In other results, patients who received a prescription for oral anticoagulant therapy were more likely to be older, male and reside in the Northeast and Midwest. These patients were also more likely to have a history of hypertension, dyslipidemia, congestive HF, diabetes, prior stroke or transient ischemic attack, prior systemic embolism and prior MI.
“The 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 the insights to improve them,” the researchers concluded. – by Dave Quaile
Disclosure: Hsu reports receiving honoraria from Janssen Pharmaceuticals, Medtronic and St. Jude Medical and consultant fees from Celladon. Please see the full study for a list of the other researchers’ relevant financial disclosures.