April 27, 2008

Throughout the 20th century, it was an American birthright that each generation would live longer than the last. Year after year, almost without exception, the anticipated life span of the average American rose inexorably, to 78 years in 2005 from 61 years in 1933, when comprehensive data first became available.

But new research shows that those reassuring nationwide gains mask a darker and more complex reality. A pair of reports out this month affirm that the rising tide of American health is not lifting all boats, and that there are widening gaps in life expectancy based on the interwoven variables of income, race, sex, education and geography. 

The new research adds weight to the political construct popularized by former Senator John Edwards of North Carolina, that there are two Americas (if not more), measured not only by wealth but also by health, and that the poles are growing farther apart.

The most startling evidence came last week in a government-sponsored study by Harvard researchers who found that life expectancy actually declined in a substantial number of counties from 1983 to 1999, particularly for women. Most of the counties with declines are in the Deep South, along the Mississippi River, and in Appalachia, as well as in the southern Plains and Texas. 

The study, published in the journal PLoS Medicine, concluded that the progress made in reducing deaths from cardiovascular disease, thanks to new drugs, procedures and prevention, began to level off in those years. Those gains, as they shrank, were outpaced by rising mortality from lung cancer, chronic obstructive pulmonary disease and diabetes. Smoking, which peaked for women later than for men, is thought to be a major contributor, along with obesity and hypertension.

“Some people are actually sinking,” said Majid Ezzati, one of the report’s authors. “The line of excuse that we can live with inequality as long as no one is getting worse is just no longer there.” 

The researchers found statistically significant declines for women in 180 of the 3,141 counties in the United States and in 11 counties for men. In an additional 783 counties for women and 48 for men, there were declines that did not reach the threshold of statistical significance. 

Of particular concern is that the gap in life expectancy between top and bottom counties expanded by two years for men and by about 10 months for women. In the worst-performing counties, all in southwestern Virginia, the drop in life expectancy over the 16-year period was nearly six years for women and two and a half years for men. In the counties showing the greatest improvement, many in the desert West, life expectancy rose nearly five years for women, and nearly seven years for men. 

The first of the two reports, released two weeks ago by the Congressional Budget Office, declared that the life expectancy gap is growing between rich and poor and between those with the highest and lowest educational attainment, even as it is narrowing between men and women and between blacks and whites. 

Pointing to the effects of smoking, obesity and chronic disease, the budget analysts wrote that “in recent decades, socioeconomic status has become an even more important indicator of life expectancy, whether measured at birth or at age 65.” Among the implications, they wrote, is that Social Security payroll taxes will become less progressive as the wealthy increase their longevity advantage over the poor.

Peter R. Orszag, the budget office’s director, said that the decline in life expectancy among some Americans was “remarkable in an advanced industrial nation” and that he believed the growing gap related to income inequality. “We’ve had sluggish income growth at the bottom and rapid income growth at the top for the last three decades,” he said.

Mr. Edwards said in an interview that the new findings on disparities demonstrate both the reach and consequences of income inequality. “The wealth and income disparity effectively infiltrates all parts of people’s lives,” he said. 

What remains to be determined by the increasingly dynamic field of research into health disparities is precisely how income interacts with factors like race, gender and education to give some people better odds of living longer. 

Taken to their extreme, the numbers can be striking: a 2006 study found that Native American men in southwestern South Dakota could expect to live to 58, while Asian women in Bergen County in New Jersey had a life expectancy of 91.

For some groups at some times, disparities can widen and shrink because of societal changes (like fluctuating homicide rates) and medical developments (like the emergence of H.I.V., or the discovery of drugs to treat it). But the causes of more lasting trends may not always be obvious, and some research suggests that income alone cannot explain away many differences.

For example, a 2006 study found that low-income whites in the northern Plains could expect to live four years longer than low-income whites in Appalachia and the Mississippi Valley. Other research indicates that health insurance status, which can relate directly to income, may not be a significant determinant of longevity. 

And yet, this month’s Harvard study showed that counties with declining or stagnant life expectancy were poorer than those with improving numbers. Recent cancer studies have found that the uninsured are more likely to fail to get a diagnosis until late stages of the disease. Research also shows that many of the behaviors that drive mortality — unhealthy diet, smoking, poor management of chronic disease — are more common among low-income Americans.
 
“We know from hundreds of studies that income does have an impact on health, but it’s not a simple relationship,” said Sam B. Harper, an epidemiologist at McGill University who has studied the issue.

Dr. Ezzati, of the Harvard School of Public Health, asked: “How much of this is pure material well being, the ability to purchase high-quality food, the ability to have a particular lifestyle? And how much of it is the impact of income on risk behaviors like alcohol and tobacco and stress mechanisms that are more psychosocial? There’s a series of debates around that that are unresolved.”

As for a prescription, Dr. Ezzati and his colleagues are realists. In a 2006 study, they concluded that “because policies aimed at reducing fundamental socioeconomic inequalities are currently practically absent in the U.S.,” life expectancy disparities would have to be addressed through public health strategies directed at reducing the risk factors that cause chronic disease and injuries.

Dr. Ezzati noted that few industrialized countries have had declines of comparable duration. “This is a very unusual pattern,” he said, “and the question we’re starting to ask is, ‘Is the fact that the bottom 20 percent is not getting better, and may be worse off, going to drive the health of the whole country?’ ”