In New Hampshire, there’s about a 5-year gap between the life expectancy for adult women at the top of the income bracket and those at the bottom. For men in the same age group, the gap’s more than nine years wide.
That's according to new data released by The Health Inequality Project, which takes a sweeping look at the relationship between income and mortality across the country.
Take Sullivan County, for example, home to the widest mortality gap between women of different income levels. There, the average life expectancy for women in the top income quartile is 90.1 years, but for those in the lowest quartile the average life expectancy is nearly a decade lower — at 80.8 years.
On the other hand, the gap in Hillsborough, Cheshire and Carroll Counties is only about four years wide.
For men, the widest gap is seen in Merrimack and Strafford Counties, according to the data. In each region, there’s a difference of more than a decade between life expectancy for men in the top income bracket and those at the bottom.
But the gap between income levels doesn't shrink as much for men across the state as it does for women. Belknap County, where that difference is the narrowest, still shows an 8-year disparity between residents at the lowest and highest incomes.
Among other things, the researchers behind the project looked at the difference in how those in the top quarter of earners fared compared to those in the bottom quarter — and how those gaps might vary depending on where a person lives.
The data also comes with a few caveats. First, the researchers used the same standards across the country to compare income. So that could affect the figures in New Hampshire, where incomes across the board tend to skew a bit higher than the national averages.
The study doesn’t specify where those income thresholds fall. According to the national income data provided publicly by the researchers, the bottom quartile includes incomes below about $29,000 for women and $32,000 for men; the upper quartile includes incomes above about $99,000 for women and $106,000 for men.
Also, the mortality data examined as part of the study only includes people between the ages of 40 and 76 — so it leaves out younger adults and children. A full explanation of the researchers’ methods and its sources can be found in this report on their findings, published in the Journal of the American Medical Association.
The researchers behind the project are also careful to say that they're not trying to suggest that a person’s income determines how long he or she will live. Rather, there are a number of other factors — geography, healthcare access, race and ethnicity, habits like smoking or exercise, and other social or economic conditions — that are tied in.
Brian Gottlob, a New Hampshire-based researcher who also examines economic and demographic trends, said it's important to remember that income's not the sole determinant of the length of a person's lifespan — but it affects a lot of other things that can, in turn, affect a person's longevity.
"It's not income, per se," Gottlob explained. "Income just happens to be kind of the intervening variable."
"If you're born poor, you don't necessarily have to expect that you're going to live five years less," he added. "What it has to do with is, did you smoke? Did you exercise? What kind of job did you have? Did you have regular access to medical care?"
Steve Norton, executive director for the New Hampshire Center for Public Policy Studies, also cautioned against singling out income as a driving factor behind a person's longevity. When looking at the data, Norton said, it's worth thinking beyond income alone — what other factors, like education or healthcare access, might account for the differences between regions?
"This is part of a broader conversation about healthcare disparity and income inequality," Norton said.