For those who live in poverty, opportunities for food, shelter and employment are often scarce. According to a study published Sunday, the poor may have yet another obstacle stacked against them: living shorter lives.
The study, called “The Association Between Income and Life Expectancy in the United States,” was co-authored by two Massachusetts Institute of Technology researchers as well as experts from Stanford University, Harvard University, the consulting firm McKinsey and Company and the Office of Tax Analysis of the United States Department of the Treasury. It detailed the huge mortality gap between the rich and poor.
“At the age of 40 years, the gap in life expectancy between individuals in the top and bottom 1% of the income distribution in the United States is 15 years for men and 10 years for women,” the study stated.
It also found that geographical location could have a large effect on a person’s lifespan. Poorer people in New York City averaged a lifespan of 81.8 years while those of Gary, Indiana averaged 77.4 years, according to MIT.
“We’ve know this for a really long time, that there’s this gap between rich and poor and health incomes,” said Sophie Godley, a professor in Boston University’s School of Public Health. “As far back as [the late 1900s], a professor named Michael Marmot did the Whitehall study, which looked at social grade and health outcome.”
The study, Godley said, found that “every step you took upwards in your economic situation improved your health outcome.”
While the relationship between mortality rates and income has already been studied, Sarah Abraham, co-author of the study and a Ph.D. candidate at MIT, said this study described the correlation more thoroughly.
“We had exact incomes at the individual level … which gave us the ability to more specifically define the association between longevity and income in the higher percentiles of the income distribution,” she said. “Also, we had the exact locations for individuals through tax records, and the receipt of their information returns.”
The research spanned three years, and several teams of people worked with the tax administration data.
“It involved people getting to know the data from other projects, which fed back into this project,” Abraham said.
Jacob Bor, a professor in SPH, called the study a “precise picture of the association between income and life expectancy in the U.S., and how it has evolved since the turn of the millennium.” Bor said the data was “striking” and significant.
“The bottom income quartile of American men has life expectancy lower than [that of Pakistan],” Bor wrote in an email. “Never before has such a complete data set been assembled and the relationship estimated so precisely.”
Bor said that though there are exceptions, the correlation between health inequity and income gaps is seen across the world.
“What you see around the world is increasingly that wealth buys people [life opportunities]; there is much more variation internationally in the poor than in the rich,” he wrote. “If you’re rich, just about anywhere you can eat well and you can have access to reasonable medical care and live in places where you can avoid toxic exposures.”
The variation in the lifespans of the poor is an indicator of the different extents to which countries invest in their health infrastructure, Bor said.
“Countries that invest in health infrastructure to benefit the poor, [such as] services, public health, education … the poor in these countries do much better,” Bor wrote. “The well-being and health of the poor ends up being quite a barometer [of] the ability of society to provide decent public services.”
Abraham said she hopes that the study will underscore the importance of improving the public sector in the United States.
“I think it should increase the salience of [health inequality and income gaps],” she said. “It is widely known and already discussed that there’s an association between income and longevity, but the magnitude has never been pinned down as exactly as we have been able to do it. By disseminating this information widely … it will help inform and encourage in terms of how we think about these issues.”
