Racial and Regional Disparities in Atrial Fibrillation Treatment and Stroke Prevention

April 5, 2010 6:17 AM CT

By Peggy Noonan and Mellanie True Hills

New studies show racial and geographic disparities in atrial fibrillation, both in people’s awareness of having afib and in the treatment they receive for it, as well as in stroke incidence and care.

One study, just published in Circulation: Journal of the American Heart Association, found that blacks who are hospitalized with the most common type of stroke are less likely than whites or Hispanics to receive evidence-based stroke care (treatment based on scientific evidence from clinical research).  For example, the study found that blacks were 16% less likely than whites to be treated with the clot-buster drug, tissue plasminogen activator (tPA), and to receive anticoagulants for atrial fibrillation.

And recently, two studies were presented at the American Stroke Association’s International Stroke Conference 2010 that showed more racial and regional disparities in atrial fibrillation awareness and treatment and stroke incidence. Both studies analyzed data from the REGARDS (REasons for Geographic and Racial Differences in Stroke) study, a national, population-based, longitudinal study of 30,239 blacks and whites aged 45 or older. The study included “oversampling” of blacks and residents of eight southeastern “stroke belt” states. 

The “stroke belt” encompasses 11 states so designated by the National Heart, Lung and Blood Institute. This study oversampled residents from eight “stroke belt” states—Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee—that are known for high rates of stroke incidence and death. Three of these states are known as the “stroke buckle”—North Carolina, South Carolina and Georgia—because they have the highest rates of stroke incidence and death in the nation.

Racial Disparities in Atrial Fibrillation Awareness and Treatment

Electrocardiograms [ECG] done at the start of the REGARDS study showed 432 people (88 black and 344 white) in the study group had atrial fibrillation. Of those, only 60% (258 people) recalled having been told by a doctor or other health professional that they had atrial fibrillation, the most common risk factor for stroke. Calculating the atrial fibrillation group’s stroke risk based on their CHADS2 scores showed that 83% (360 people) of those who had atrial fibrillation also had at least one additional stroke risk factor.

“We found that among individuals confirmed to have AF by ECG, blacks were approximately one third as likely to be aware that they had AF as whites,” reports James F. Meschia, MD, a neurologist at the Mayo Clinic in Jacksonville, Florida, and lead author of the study “Racial Disparities in Awareness and Treatment of Atrial Fibrillation: The REasons for Geographic and Racial Differences in Stroke (REGARDS) study” which was published simultaneously with the conference in Stroke: Journal of the American Heart Association.  

It’s not clear why so few knew they had atrial fibrillation, but the researchers suggest some might not have had symptoms, and some may have been diagnosed but didn’t remember or may not have understood what their diagnosis meant.

Although Coumadin (warfarin) reduces stroke risk by about 60% in people who have atrial fibrillation, Dr. Meschia’s study found that only 80% of the people who knew they had atrial fibrillation were taking the blood-thinning medicine and “blacks were approximately one-fourth as likely to be treated with warfarin as whites.”  We don’t know why this racial disparity exists, but it may put blacks at higher risk of stroke and that, “in turn, could contribute to the higher stroke mortality among blacks.” 

It’s not clear why people with atrial fibrillation aren’t being treated to reduce their risk of stroke, but Dr. Meschia’s team notes this may reflect a gap between evidence and practice. In other words, although evidence from research shows treatment works, there’s a gap between what the labs find and what happens in the doctor’s office where people are treated. Another possibility is that doctors may be reluctant to treat afib patients with blood-thinners because the patients have other health problems, such as uncontrolled high blood pressure or risk of hemorrhagic (bleeding) stroke, or patients may just refuse to take anticoagulants.

Racial and Geographic Disparities in Stroke Incidence

The second analysis of the REGARDS data was led by co-principal investigators Virginia J. Howard, Ph.D., associate professor of epidemiology at the School of Public Health at the University of Alabama at Birmingham (UAB) and George Howard, Dr.PH., a UAB professor of biostatistics. Their team found that more strokes occurred among blacks, men, older people, and people living in the eight stroke belt states in the REGARDS study.

Deaths from stroke were 20% higher in the stroke belt and 40% higher in the stroke buckle. “These are the first national data describing racial and regional disparities in stroke incidence and confirm the excess stroke mortality among blacks and in the stroke belt region of the US,” Dr. [Virginia] Howard reports.  

“African-Americans age 65 and younger are more than twice as likely to have a stroke compared with Caucasians in any region, and people who have a stroke are more likely to die in the South than elsewhere,” according to the researchers.

“We found in the 45-54 age group that blacks have a 2.5-fold greater stroke rate compared to whites, which is startling,” Dr. [Virginia] Howard said. “That disparity evens out and changes in older Americans. In fact, the racial differences reverse, so by the time they reach about age 80 and older, whites have a higher stroke rate compared with blacks.”

The team’s research also showed that both awareness of having atrial fibrillation and treatment for it “was about two-thirds less” among blacks compared to “otherwise similar whites”, and blacks were less likely to receive warfarin for atrial fibrillation. She notes the “potential reasons for the disparity in warfarin treatment warrant further investigation.”

We’ve known for a long time that blacks have a higher death rate from stroke than whites but we didn’t have much information to explain why. This research shows that “certain subgroups are more at risk and need to pay serious attention to their risk factors to prevent stroke,” Dr. [George] Howard says.

Comments: This research makes it clear that we need to continue to focus on awareness of atrial fibrillation and the resultant stroke risk, not just in the stroke belt but everywhere. And we cannot just take stroke for granted as something that “runs in families”, especially in the stroke belt and in certain populations. We can, and will, wipe out afib-related strokes.

To learn more, see:

Peggy Noonan specializes in writing about health for consumers and medical professionals. She writes for leading national magazines and consumer publications as well as StopAfib.org.

Mellanie True Hills is founder and CEO of StopAfib.org and an atrial fibrillation survivor.