Assessing Oral Anticoagulant Prescription for Atrial Fibrillation

The CHADS₂ and CHA₂DS₂-VASc scores have been developed to help estimate the risk of thromboembolism in patients with AF based on specific risk factors. “Current guidelines call for using these tools to determine the absolute risk of stroke and help clinicians decide if prescription oral anticoagulants (OACs) are warranted to reduce stroke risk,” says Jonathan Hsu, MD, MAS.

Addressing the Issue

Despite the well-established association of AF with stroke, several large-scale studies indicate that OAC prescription rates are low among at-risk candidates. “Although OACs can benefit patients with AF, little is known about the extent to which OAC prescribing occurs in real-world practice to help reduce the risk of stroke,” says Dr. Hsu. To address this research gap, he and his colleagues had a study published in JAMA Cardiology that evaluated the prevalence of OAC prescription by cardiovascular specialists.

For the study, the authors used outpatient data from a large national registry to examine the real-world prevalence of treatment with OACs, antiplatelet therapy only, or no antithrombotic therapy in patients with AF based on CHADS₂ and CHA₂DS₂-VASc scores. The primary outcome was prescription of an OAC with warfarin sodium or a non–vitamin K antagonist OAC. In total, more than 429,000 outpatients with AF were included in the analysis.

Results of the study showed that cardiovascular disease specialists were more likely to prescribe an OAC in patients with more stroke risk factors, based on both the CHADS₂ score and the CHA₂DS₂-VASc score. Each 1-point increase in risk score correlated with a higher likelihood of AF patients receiving an OAC prescription when compared with aspirin-only prescriptions. “However, fewer than 50% of all patients at the highest ranges of stroke risk were prescribed an OAC,” Dr. Hsu says. Overall, only about 45% of patients were prescribed an OAC, approximately 26% received aspirin only, nearly 6% received aspirin plus a thienopyridine, and almost 24% received no antithrombotic therapy at all.

Assessing Implications

“Our findings bring attention to important gaps in the appropriate treatment of patients with AF who are at the highest risk of stroke,” says Dr. Hsu. “They also highlight the need to use the CHADS₂ and CHA₂DS₂-VASc scores and act upon those results. Future research should aim to understand the reasons behind these gaps in care and insights to improve them.” He adds that the reasons for variations in treatment patterns remain unclear, but may be related to physician and patient concerns about the bleeding risks associated with OACs. Other possible reasons include differences in insurance coverage, socioeconomic status, or exposure to guidelines through educational programs for healthcare professionals who practice in different regions of the country.

Considering the significant variability that was observed among individual practices, Dr. Hsu and colleagues recommend that practices focus on factors that are the least and most compliant with guideline adherence. Such efforts may prove fruitful in efforts to rectify inadequate anticoagulation prescriptions more broadly.

Jonathan Hsu, MD, MAS, FACC, FAHA, FHRS, has indicated to Physician’s Weekly that he has worked as a consultant for St. Jude Medical, Medtronic, Biotronik, Bristol-Myers Squibb, and Janssen Pharmaceuticals and has received grants/research aid from Biosense-Webster and Biotronik.