Donald Trump addresses his supporters during a rally at the Charleston Civic Center on May 5, 2016 in Charleston, WV.

Ever since Donald Trump's improbable political rise, many have attributed his appeal among the white, male voter base to economic anxiety. Faced with unemployment and wage stagnation, these voters elected a president who promised to fight for jobs.

A study published on Wednesday in the Journal of General Internal Medicine offers an additional explanation: declining health and rising death rates in rural Republican bastions helped tilt the presidential election toward Trump.

"Changes in life expectancy were an independent factor in voting choices. Reduced health prospects are an important marker of dissatisfaction, discouragement, hopelessness, and fear — sentiments that may have resonated with voters who sided with President Trump," said Dr. Lee Goldman, the study leader and chief executive of the Columbia University Medical Center.

Other studies have added more elements to the economic anxiety narrative too. A study published in the Proceedings of the National Academy of Sciences suggests that Trump voters were driven over a fear of losing their status. Last year, a Public Religion Research Institute survey of more than 3,000 people found that fears of cultural displacement pushed the white working class toward Trump.

White Americans from rural America, with less education and lower income levels, voted disproportionately for Trump, according to the Columbia study. This group is increasingly victim to "deaths of despair" related to alcohol, drugs and suicide, the researchers said.

They also find that counties with a net gain in individuals who voted for the Republican candidate had a 15 percent higher age-adjusted death rate in 2015 than counties with a net gain in Democratic voters. The increase in death rates due to "deaths of despair" was also 2.5 times higher in counties where Republicans made gains, compared with counties where Democrats made gains.

Pro-Trump counties also had a 7.4 percent higher age-adjusted death rate than counties won by Hillary Clinton. Counties in which Trump's percentage vote in 2016 was higher than John McCain's percentage vote in 2008 had a 15 percent higher age-adjusted death rate.

The study also suggests that modest reductions in death rates in Michigan, Pennsylvania and Wisconsin might have shifted their electoral votes to Hillary Clinton.

The study uses publicly available data from each of the country's more than 3,100 counties to compare changes in presidential voting from 2008 to 2016 with changes in death rates, controlling for factors like race, income, education and unemployment.

"Although life expectancy is increasing in many parts of the country, especially in urban areas, we're not seeing nearly the same gains in rural and middle America," said Goldman. "We shouldn't underestimate the degree to which some portions of the country have been left behind in terms of their health. And it's not surprising that health disparities correspond with voting behavior."

The conclusions are largely consistent with a 2017 study in American Journal of Public Health, which found that counties where life expectancy stagnated or declined saw a 10-point increase in the Republican vote share between 2008 and 2016.

"Regardless of your political persuasion, our paper suggests that if health disparities were important enough to influence presidential voting, they may have an even broader impact on our country's future than we had imagined," Goldman said.