Income inequality and gov­ern­ment social spending. These are hot-​​button issues in this year’s pres­i­den­tial pri­maries: the rich get­ting richer, the poor get­ting poorer, and the government’s role in closing the gap - or not.

For Daniel Kim, asso­ciate pro­fessor in the Bouvé Col­lege of Health Sci­ences at North­eastern, such gaps can be a matter of life and death.

In a paper pub­lished Tuesday in the journal Pre­ven­tive Med­i­cine, he exam­ined the effects of U.S. state and local social spending - monies for wel­fare, edu­ca­tion, and health - on mor­tality and drew not just a cor­re­la­tion, as the few ear­lier studies on the sub­ject have done, but opened the door to infer­ring a cause-​​and-​​effect rela­tion­ship between higher spending and longer lives for the more than 430,000 adults he assessed across the country.

The find­ings are sobering. “Each addi­tional $250 spent per person per year on wel­fare pre­dicted a 3 per­centage point lower prob­a­bility of their dying from any cause,” says Kim, an expert on the social and eco­nomic deter­mi­nants of pop­u­la­tion health. “Wel­fare” encom­passes sev­eral com­po­nents, including state sup­ple­ments to unem­ploy­ment insur­ance, worker incen­tive pro­grams, public assis­tance pro­grams, and ser­vices for the elderly and disabled.

“While some pres­i­den­tial can­di­dates have argued for more gov­ern­ment social spending from a soci­etal fair­ness point of view, my find­ings high­light the health ben­e­fits of wel­fare and edu­ca­tion spending, in par­tic­ular, and the harm that increasing or main­taining the gap between the rich and the poor can have on everyone’s health.”

An impact on all Americans

In his study, Kim exam­ined six leading causes of death in the U.S. in older adults: coro­nary heart dis­ease, stroke, colon cancer, chronic obstruc­tive pul­monary dis­ease, dia­betes, and sui­cide. Most affected by state and local gov­ern­ment social spending was coro­nary heart dis­ease, which kills more than 370,000 people annu­ally, according to the Cen­ters for Dis­ease Con­trol and Prevention.

Kim found that each addi­tional $250 spent per person per year on wel­fare reduced the chances of dying from heart dis­ease by nearly 2 per­centage points, and the same amount spent per person on edu­ca­tion reduced the chances by almost 1 per­centage point. In con­trast, his analysis showed that the bigger the gap between the rich and the poor, the greater the chance a person had of dying.

“These reduc­tions in mor­tality com­pare to the health ben­e­fits that we see in patients who receive suc­cessful treat­ment for high blood pres­sure or high cho­les­terol,” says Kim. “Increasing social spending in these areas could impact all Amer­i­cans, not just those who have access to clin­ical treatment.”

Real - life ben­e­fits and harm

That income inequality affects health and mor­tality is not new. Research has shown that wider gaps in income gen­er­ally cor­re­late with a shorter average lifespan. But less than a handful of studies have addressed the effects of social spending on health and mor­tality. Fur­ther­more, the few studies on social spending con­sider data only at one point in time - a single year - and only at the state level.

Kim, on the other hand, used the National Lon­gi­tu­dinal Mor­tality Study, a nation­ally rep­re­sen­ta­tive dataset, to track indi­vid­uals sur­veyed in the 1980s for more than a decade. Fol­lowing people over time enabled him to use sta­tis­tical methods common to eco­nomic analyses but rare in public health studies that “con­trolled” for mul­tiple fac­tors at the state level in order to zero in on the risks of death asso­ci­ated directly with dol­lars spent for the individual.

A lim­i­ta­tion of obser­va­tional, as opposed to clin­ical or exper­i­mental, studies is that they can’t show mech­a­nisms of action - that is, how one vari­able, say, a drug, brings about an effect, say, the pro­duc­tion of a par­tic­ular pro­tein that can be mea­sured in the blood. And they can only show a link between a vari­able and an effect, not that the vari­able caused the effect. We’ve all heard, for example, about research showing that antioxidant - rich foods like broc­coli cor­re­late with a lower cancer risk. That is very dif­ferent from saying that eating broc­coli pre­vents cancer.

Kim’s latest work is like an obser­va­tional study on steroids. Its rig­orous method­ology per­mits him to better “infer cause - and - effect rela­tion­ships,” he says, between the causes, in this case greater social spending and income inequality, and the effects, reduced mor­tality from a variety of diseases.

“The Great Reces­sion of the past decade led to unprece­dented social spending cuts in 46 U.S. states,” says Kim. “Mean­while, the divide between the rich and the poor has surged in 45 states over the past three decades, reaching levels that we haven’t seen since the Great Depression.

“We cer­tainly need to explore my find­ings further - such as iden­ti­fying which spe­cific wel­fare and edu­ca­tion pro­grams ben­efit health. But I hope they will help launch a public dis­cus­sion about the real - life health ben­e­fits and harms that state pol­i­cy­makers’ deci­sions can have on all of us.”

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Journal
  Preventive Medicine