Growing 'mortality gap' detected between Democratic and Republican counties

"In an ideal world, politics and health would be independent of each other and it wouldn't matter whether one lives in an area that voted for one party or another," said corresponding author Haider Warraich, MD, of the Division of Cardiovascular Medicine at the Brigham. "But that is no longer the case. From our data, we can see that the risk of premature death is higher for people living in a county that voted Republican."

Warraich and colleagues used data from the Wide-ranging OnLine Data for Epidemiologic Research (CDC WONDER) database and the MIT (Massachusetts Institute of Technology) Election Data and Science Laboratory. They classified counties as Democratic or Republican based on the way the county had voted in the previous presidential election and adjusted for age when calculating mortality rates.

Overall, the team found that mortality rates in Democratic counties dropped from 850 deaths per 100,000 people to 664 (22 percent), but in Republican counties, mortality rates declined from 867 to 771 (11 percent). When the team analyzed by race, they found that there was little gap between the improvements in mortality rates that Black and Hispanic Americans experienced in Democratic and Republican counties. But among white Americans, the gap between people living in Democratic versus Republican counties was substantial.

The mortality gap remained consistent when the researchers looked only at counties that had voted Republican or Democratic in every presidential election year studied and when they looked at gubernatorial elections. Democratic counties experienced greater reductions in mortality rates across most common causes of death, including heart disease, cancer, chronic lower respiratory tract diseases, diabetes, influenza and pneumonia, and kidney disease.

The authors note that the widening gap in death rates may reflect the influence of politics on health policies. One of the inflection points detected in the study corresponds to the Affordable Care Act (ACA), which was passed in 2010. More Democratic states than Republican states adopted Medicaid expansion under the ACA, which expanded health insurance coverage to people on a low income.

The study detects an association between political environment and mortality but does not definitively determine the direction of the association or the specific factors that may explain the link between the two. The authors did not study the effect of flipping political environments -- that is, counties that switched from voting Democratic or Republican to voting for the other party -- on health outcomes, which could be an area of future study. The study period ended in 2019, before the start of the COVID-19 pandemic, which may have had an even more profound impact on the mortality gap.

"Our study suggests that the mortality gap is a modern phenomenon, not an inevitability," said Warraich. "At the start of our study, we saw little difference in mortality rates in Democratic and Republican counties. We hope that our findings will open people's eyes and show the real effect that politics and health policy can have on people's lives."

Disclosures: Warraich is an advisor for Embrace Prevention Care; co-author Rishi Wadhera receives research support from the National Heart, Lung, and Blood Institute (grant K23HL148525-1); co-author Karen E. Joynt Maddox previously did contract work for the U.S. Department of Health and Human Services.