June 09, 2016
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Higher stroke mortality rate among middle-aged blacks tied to elevated incidence rate

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The elevated rate of stroke mortality in blacks aged 45 to 54 years compared with whites of the same age is almost entirely due to the increased incidence rate of stroke in middle-aged blacks, according to new data from the REGARDS study.

George Howard, DrPH, professor of biostatistics at the University of Alabama at Birmingham’s School of Public Health, told Cardiology Today the results shift the tone of the debate regarding racial disparity in stroke mortality.

George Howard

“If we reduce the number of strokes suffered by blacks, we reduce that death-rate gap,” Howard said in an interview. “For example, hypertension is one of the key factors in suffering a stroke. In this study, 51% of whites had hypertension while 71% of blacks suffered from it. That’s an incredible gap, and we need to fix this difference to fix the larger number of strokes in blacks.”

The researchers assessed whether black vs. white disparity in stroke incidence reflected black vs. white disparity in stroke mortality, and then determined to what degree the disparity in stroke mortality was caused by difference in stroke incidence or in 30-day case fatalities.

The study population was 29,681 demographically and geographically varied participants from the REGARDS cohort, enrolled from 2003 to 2007 and followed up at 6-month intervals after enrollment.

Incidence, mortality similar

At age 45 years, the HR for stroke mortality in blacks vs. whites is approximately 4, decreasing to approximately 1 at age 85 years, according to the results.

Howard and colleagues found a similar pattern in stroke incidence: The HR for stroke incidence in blacks vs. whites declined from approximately 3 at age 45 to 54 years to approximately 1 at age 75 to 84 years.

However, the researchers found that although odds of a stroke being fatal increased with each decade of age (OR = 1.61; 95% CI, 1.35-1.91), there was no association between race and case fatality (OR = 1.2; 95% CI, 0.89-1.62).

Call for practice change

In the United States in 2014, there were 22,384 stroke events occurring in blacks beyond what would be expected relative to rates in whites. Howard told Cardiology Today those numbers should dictate changes in clinical practice.

“We need to be targeting blacks in their 20s, 30s and 40s to work to prevent the development of stroke and heart disease risk factors in the first place,” he said. “There are some concrete steps we can be taking. Emphasize the importance of using common sense — don’t gain weight; eat better and avoid salt, especially; exercise regularly. Then we need to work with those who develop hypertension and diabetes to control their BP and glucose levels.”

Howard said the percentage of deaths from stroke has decreased 46% in the past 13 years, which is a cause for optimism, but closing the racial-disparity gap in stroke mortality should remain paramount.

“Stroke is a tremendously challenging condition to study,” he said. “At the age of 65, only 1% to 2% of the American population will suffer a stroke each year, which limits your research possibilities. I don’t know of many studies as big as ours. But if we care about the extra deaths in the black population, we should go through the research and make a huge effort to understand why.”

Howard said diet plays a role in the disparity, noting the lack of access many blacks have to proper supermarkets, but another factor plays an even larger role.

“There’s a technology gap between blacks and whites, and between urban and rural areas,” Howard said. “And with better technology comes more informed choices. Especially in the South, where I was raised, people eat so many fried foods and drink sweet tea. You wouldn’t recognize some of the foods on my plate when I was growing up, but I certainly don’t eat that way anymore. It’s changing. There’s definitely more awareness now.”

There also is a significant financial motive for reducing the racial disparity in stroke, Howard said in a press release.

“The magnitude of the public-health burden of the racial disparity in stroke is staggering …” he said. “With a lifelong cost of $104,000 … the [racial disparity] in stroke costs America more than $2.3 billion annually.” – by James Clark

For more information:

George Howard, DrPH, can be reached at Department of Biostatistics, LHL 454, University of Alabama at Birmingham, Birmingham, AL 35294; email: ghoward@uab.edu.

Disclosure: The researchers report no relevant financial disclosures.