Oral anticoagulants for stroke prevention may be underprescribed in outpatients with AF
Specialists were more likely to prescribe an oral anticoagulant as the number of stroke risk factors increased as measured by the CHADS2 and CHA2DS2-VASc scores, the study noted.
Less than half of patients with atrial fibrillation (AF) at the highest risk of stroke were prescribed an oral anticoagulant for prevention, a recent study of outpatient cardiology practices found.
Using 2008 to 2012 data from PINNACLE, the American College of Cardiology's quality improvement registry comprised of 429,417 patients with AF treated by cardiovascular specialists at 144 U.S. practices, researchers examined the number of prescriptions written for oral anticoagulants. Results were published online on March 16 by JAMA Cardiology.
The primary outcome was treatment with warfarin, dabigatran, or rivaroxaban, the FDA-approved oral anticoagulants for stroke prevention during the study time frame. For patients not receiving anticoagulant therapy, researchers determined whether they were treated with an antiplatelet agent (aspirin alone or aspirin plus a thienopyridine) or received neither therapy.
In total, 192,600 patients, or 44.9%, were prescribed an oral anticoagulant (90.3% warfarin, 7.7% dabigatran, and 2.0% rivaroxaban). As for antiplatelets, 111,134 patients (25.9%) were prescribed aspirin only and 23,454 patients (5.5%) were prescribed aspirin plus a thienopyridine. No antithrombotic therapy was prescribed in 102,229 patients (23.8%).
Because researchers only used data from each patient's index visit, they conducted a sensitivity analysis and found that 4,859 patients (2.1%) who were not prescribed an anticoagulant at baseline received a prescription during a follow-up visit within 1 year. The median practice treatment prevalence with anticoagulant therapy was 51.7%, (interquartile range, 37.7% to 58.3%).
Specialists were more likely to prescribe an oral anticoagulant as the number of stroke risk factors increased as measured by the CHADS2 and CHA2DS2-VASc scores. Patients with a CHADS2 score of 3 and a CHA2DS2-VASc score of 5 were most often prescribed anticoagulants (50.6% and 49.7%, respectively). Each 1-point increase in either risk score was associated with about 15% greater adjusted odds of oral anticoagulant prescription. However, researchers observed a plateau effect, as patients with a CHADS2 score exceeding 3 or a CHA2DS2-VASc score exceeding 4 were often not prescribed anticoagulants. Less than half of all higher-risk patients received anticoagulant prescriptions.
The reasons for these findings are unknown but may involve concerns regarding bleeding risk, and practice patterns may have changed since the study time frame because 4 non-vitamin K antagonist oral anticoagulants are now FDA-approved, the study authors noted.
They noted additional limitations to their study, such as how the registry does not provide enough information to calculate bleeding risk. In addition, researchers excluded 28,088 patients on the registry who were not candidates for antiplatelet or anticoagulant therapy, but specific data for the exact reasons for contraindication were unavailable.
According to an accompanying editorial, “The data … make an important contribution and help highlight that significant opportunity to improve care exists among many outpatient practices, such as those participating in the PINNACLE Registry.”
Now that these quality gaps have been documented, next steps should involve quality improvement, the editorial stated. Possible interventions include configuring electronic health records to remind clinicians when a patient has an indication for oral anticoagulation and providing better patient education, as survey data suggest that only 64% of patients with AF understand their increased risk for stroke, the editorialists wrote.