Political environment and mortality rates in the United States, 2001-19: population based cross sectional analysis

Objective: To assess recent trends in age adjusted mortality rates (AAMRs) in the United States based on county level presidential voting patterns.

Design: Cross sectional study.

Setting: USA, 2001-19.

Participants: 99.8% of the US population.

Main outcome measures: AAMR per 100 000 population and average annual percentage change (APC).

Methods: The Centers for Disease Control and Prevention WONDER database was linked to county level data on US presidential elections. County political environment was classified as either Democratic or Republican for the four years that followed a November presidential election. Additional sensitivity analyses analyzed AAMR trends for counties that voted only for one party throughout the study, and county level gubernatorial election results and state level AAMR trends. Joinpoint analysis was used to assess for an inflection point in APC trends.

Results: The study period covered five presidential elections from 2000 to 2019. From 2001 to 2019, the AAMR per 100 000 population decreased by 22% in Democratic counties, from 850.3 to 664.0 (average APC -1.4%, 95% confidence interval -1.5% to -1.2%), but by only 11% in Republican counties, from 867.0 to 771.1 (average APC -0.7%, -0.9% to -0.5%). The gap in AAMR between Democratic and Republican counties therefore widened from 16.7 (95% confidence interval 16.6 to 16.8) to 107.1 (106.5 to 107.7). Statistically significant inflection points in APC occurred for Democratic counties between periods 2001-09 (APC -2.1%, -2.3% to -1.9%) and 2009-19 (APC -0.8%, -1.0% to -0.6%). For Republican counties between 2001 and 2008 the APC was -1.4% (-1.8% to -1.0%), slowing to near zero between 2008 and 2019 (APC -0.2%, -0.4% to 0.0%). Male and female residents of Democratic counties experienced both lower AAMR and twice the relative decrease in AAMR than did those in Republican counties. Black Americans experienced largely similar improvement in AAMR in both Democratic and Republican counties. However, the AAMR gap between white residents in Democratic versus Republican counties increased fourfold, from 24.7 (95% confidence interval 24.6 to 24.8) to 101.3 (101.0 to 101.6). Rural Republican counties experienced the highest AAMR and the least improvement. All trends were similar when comparing counties that did not switch political environment throughout the period and when gubernatorial election results were used. The greatest contributors to the widening AAMR gap between Republican and Democratic counties were heart disease (difference in AAMRs 27.6), cancer (17.3), and chronic lower respiratory tract diseases (8.3), followed by unintentional injuries (3.3) and suicide (3.0).

Conclusion: The mortality gap in Republican voting counties compared with Democratic voting counties has grown over time, especially for white populations, and that gap began to widen after 2008.