Emily O’Brien, Duke University – AFib

Emily O'BrienAtrial fibrillation is all too common.

Emily O’Brien, a medical instructor in the Department of Medicine at Duke University Medical Center and the Health Services Research group at the Duke Clinical Research Institute, is working to treat the cardiac condition.

Dr. O’Brien’s primary research focus is care delivery and outcomes in observational cardiovascular disease cohorts, with specific applications to atrial fibrillation, stroke, and hypercholesterolemia. Her research interests include comparative effectiveness, patient-reported outcomes, quality of care, and medication adherence. Dr. O’Brien received her Ph.D. in Epidemiology from the University of North Carolina at Chapel Hill.



Nearly all women and people over 65 in the U.S. with atrial fibrillation are advised to take blood thinners under new guidelines from the American Heart Association, American College of Cardiology and Heart Rhythm Society.

These guidelines were broadened in 2014 and now consider additional stroke risk factors to determine who should take blood thinners. Notably, being female is now included in the guidelines as a contributing risk factor for stroke.

Atrial fibrillation, or AFib, is an irregular heartbeat that can lead to blood clots, stroke, heart failure and other heart-related complications. It affects about 2.7 million people in the U.S. Anticoagulant drugs, or blood thinners, help prevent blood from clotting and potentially causing stroke.

Because stroke risk scores are key in deciding whether a patient with AFib needs blood thinners, we were interested in how using a new risk score would affect the number of patients recommended for treatment. To assess the impact of these new guidelines, we reviewed data from a registry called ORBIT that included 10,132 AFib patients from 176 sites across the U.S.

We examined patients’ age, gender and other risk factors such as prior congestive heart failure, high blood pressure, diabetes and prior stroke.

We found that the full adoption of the guidelines could reclassify nearly 1 million people with AFib who previously weren’t recommended for treatment with blood thinners.

The overall proportion of AFib patients recommended for blood-thinning drugs would increase by 19 percent as a result of the new guidelines, from about 72 percent of all AFib patients to 91 percent. In our study, 2 out of every 3 patients with Afib patients who were not previously recommended for treatment were reclassified.

We observed a similar increase for women with AFib. The new recommendations also lower the age at which patients are considered at risk for stroke from 75 to 65; with the new guidelines, about 99 percent of AF patients over 65 were recommended for blood thinners.

What we don’t know yet is the extent to which doctors in community practice will incorporate the guidelines into their clinical routines, and what that will mean for the long-term outcomes for those patients. That will be the next step for our research.