Racial and Geographic Disparities Seen in Stroke Incidence and Racial Differences in AF Treatment

Pauline Anderson

March 01, 2010

March 1, 2010 (San Antonio, Texas) — New research from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study has uncovered racial and geographic disparities in stroke incidence and racial differences in receiving proper diagnoses and treatment for atrial fibrillation (AF).

One study found that blacks and those living in the so-called stroke belt that stretches across the southeastern United States are most likely to have a stroke.

Another report shows that blacks are more likely than whites to be unaware they have AF and are less likely to be taking warfarin if they have been diagnosed as having the condition.

Both studies used data from the REGARDS study, which enrolled 30,239 participants across the United States aged 45 years or older between January 2003 and October 2007.

Findings were presented here during the International Stroke Conference 2010, and the latter report was simultaneously published online February 26 in Stroke.

First National Data

In the stroke incidence analysis, researchers provided the first national data describing racial and regional disparities. They reviewed data on 26,610 REGARDS participants who had not had a stroke at baseline and documented 352 strokes during a median follow-up of 3.9 years.

The study found that patterns of stroke incidence are similar to those of stroke mortality drawn from US death certificate data. "We're actually contrasting the mortality data with what we now have from incidence data," the study’s lead author Virginia J. Howard, PhD, associate professor of epidemiology, School of Public Health, University of Alabama at Birmingham, told Medscape Neurology. "Basically, we're seeing a very, very similar pattern with higher stroke incidence in blacks compared to whites."

The racial difference was most apparent in younger people. In the group aged 45 to 54 years, blacks had almost a 2.5 times higher stroke incidence compared with whites at 192 per 100,000 vs 74 per 100,000.

"We have seen significant declines in stroke mortality overall, which has been one of the great public health achievements of the 20th century, but while we have reduced stroke deaths, we still have these disparities," said Dr. Howard.

Only some of the higher incidence of stroke among blacks is due to the higher rate of uncontrolled hypertension or to diabetes, she said. "There are other factors that have to be considered, and it could be things like diet, lifestyle, physical activity, or maybe even the infection rate."

Geographic Disparities

The study also found geographic disparities. The stroke rate was more than 12% higher among those living in the "stroke belt" — North Carolina, South Carolina, Georgia, Alabama, Arkansas, Louisiana, Tennessee, and Mississippi. The rate was 410 per 100,000 outside this belt compared with 457 per 100,000 inside the belt and even higher — 485 per 100,000 — in the "buckle," the area that includes the coastal plain of North Carolina, South Carolina, and Georgia.

The large number of blacks living in this region can explain only some of this difference, said Dr. Howard. "That's a part of it, but even after you control for that, it's still higher, so blacks who live in the stroke belt have 2 strikes against them."

Targeted messages are needed that emphasize that stroke is a preventable disease, said Dr. Howard.

Culturally Sensitive Message

Offering his comments on this research, Michael Sloan, MD, MS, director of the Tampa General Hospital/University of South Florida Stroke Program, and professor of neurology at the University of South Florida, Tampa, said that getting minorities to recognize and act on stroke symptoms might require a new public awareness approach.

"A lot of it is crafting a message and presenting it in a culturally sensitive and appropriate manner," said Dr. Sloan. "The marketing and advertising people have this down, so obviously we can learn something from that group in terms of crafting and conveying the message."

But everyone in the health care system plays a role in helping to change behaviors, said Dr. Sloan. "We can do a better job collectively — governments, medical organizations, physicians, other health care providers, and, of course, the individual patients who have to be willing to take the advice and act on it."

There is still more research to be done to answer questions related to racial and geographic disparities in stroke incidence, but this is the "first pass," said Dr. Sloan. The REGARDS study group "will be looking at a lot of other things so we expect more from this group" that hopefully will address some of these issues.

Warfarin Makes "A Huge Difference"

In the separate analysis of REGARDS data, lead author James F. Meschia, MD, a neurologist at the Mayo Clinic, Jacksonville, Florida, and colleagues found that among 432 study participants (88 blacks, 344 whites) who had AF confirmed by electrocardiogram, blacks were both less likely to know they had AF and less likely to be treated with warfarin.

Among those with AF, 88% had at least 1 additional CHADS2 risk factor, and 60% knew they had AF, the study authors report.

The odds of black subjects being aware of their AF was one-third that of whites. Of those who were aware they had AF, the odds of them receiving treatment was only one-fourth as great as whites.

Table. REGARDS: AF Awareness and Treatment in Blacks vs Whites

Endpoint Odds Ratio (95% CI)
AF awareness 0.32 (0.20 – 0.52)
Warfarin treatment 0.28 (0.13 – 0.60)

AF = atrial fibrillation; CI = confidence interval; REGARDS = REasons for Geographic and Racial Differences in Stroke

"These disparities are a problem," said Dr. Meschia in a statement from the American Heart Association/American Stroke Association. "For patients who are able to take warfarin, it makes a huge difference. Stroke trials have shown that warfarin reduces the risk for stroke by 60%."

Dr. Meschia noted that not all patients should receive warfarin because of the risk of bleeding.

The healthcare system needs to better screen for and inform people about whether they have AF, and more study is needed to shed light on the causes of the disparity in warfarin treatment, said Dr. Meschia.

For his part, Dr. Sloan said this second report generates more questions than it answers. "If blacks are aware they have symptoms of AF, there are any number of reasons why they don't get treated," said Dr. Sloan. "They may not recognize the significance of the symptoms or they may not have easy access to medical care. They also may be afraid to go to the doctor. They may not be able to afford it, they may not like doctors, or they may not trust doctors."

Since the research continued only until 2007, "I would imagine that it's probably even more true today given the present economic conditions," said Dr. Sloan.

REGARDS is supported by the National Institutes of Neurological Disorders and Stroke. The authors have disclosed no relevant financial relationships.

International Stroke Conference (ICS) 2010: Abstracts 158 and 160. Presented February 26, 2010. Stroke. Published online February 26, 2010.

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