Fewer Americans are dying from heart disease compared with 40 years ago, but not all parts of the country are showing the same downward trend, a new federal government study finds.
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Researchers say the nation's heart-disease hotbeds have largely migrated south. In the 1970s, U.S. counties with the highest death rates from heart disease were clustered in the Northeast; now they are concentrated in Southern states, especially the deep South.
The study, published March 22 in the journal Circulation, can only show the trend - and not the reasons for it, said lead researcher Michele Casper.
"But from other studies we know the socioeconomic conditions of a county can affect rates of smoking and obesity, or whether people have access to affordable, healthy food, for example," said Casper, an epidemiologist at the U.S. Centers for Disease Control and Prevention.
According to Dr. Donald Barr, a professor at Stanford University School of Medicine in California, the issue is clearly social.
Southern states, he said, often have higher rates of obesity, type 2 diabetes and kidney disease, which are risk factors for heart disease. And social conditions - from poverty and low education levels, to racial injustice - are at the root of the problem, Barr said.
"Social risk factors for heart disease are more common in the South," he said. "This disparity [in heart disease deaths] is not about hospital care. It's about broader social structure."
For the study, Casper's team looked at U.S. counties' rates of death from heart disease between 1973 and 2010. Nationwide, the researchers found, those deaths fell by about 62 percent.
But counties varied widely, the study found. In counties with the smallest improvements, heart disease deaths fell by anywhere from 9 percent to 50 percent. And those counties were concentrated in Alabama, Arkansas, Louisiana, Mississippi, Oklahoma and parts of Texas.
In contrast, counties with the greatest improvements saw death rates drop between 64 percent and 83 percent - and they were mostly in the North.
In the early 1970s, almost half of counties in the Northeast were considered to have high rates of death from heart disease, versus the rest of the country. By 2010, that had plummeted to just 4 percent of Northeastern counties.
The South, however, has seen the opposite trend. In 2010, 38 percent of the region's counties had high death rates from heart disease, versus 24 percent in the 1970s.
Like the Northeast, the Midwest showed a decline in counties with high heart disease death rates. In 2010, 6 percent of its counties fell into that category. The West had, by far, the lowest death rates in the 1970s, and it's still home to most of the nation's "low-rate clusters," the study found. ■