Identifying Long Term All-Cause Mortality Trends in US Counties from 2011 to 2020 and Associated Spatio-Temporal...

Primary care is fundamental to health equity, with evidence linking primary care physician (PCP) supply to reduced mortality and improved population health, particularly in underserved communities. While cross-sectional studies demonstrate associations between PCP availability and mortality rates, the relationship between sustained primary care access patterns and long-term mortality trajectories remains poorly understood. This study investigates the relationship between primary care physician supply trends and age-adjusted all-cause mortality trajectories in U.S. counties from 2011 to 2019.

We utilized group-based trajectory modeling to identify distinct mortality trajectory patterns among U.S. counties from 2011 to 2019. County-level age-adjusted all-cause mortality rates were obtained from the CDC, and primary care physician supply data from HRSA. We examined associations between baseline PCP supply, changes in PCP supply over time, and mortality trajectory group membership using multinomial logistic regression, adjusting for sociodemographic factors including poverty rates, unemployment, racial composition, and rurality.

Eight distinct mortality trajectory groups were identified, revealing persistent and widening disparities across U.S. counties. Counties with favorable mortality trajectories had significantly higher baseline PCP supply and experienced less decline in physician availability. Every increase in 5 primary care physicians per 100 000 population at baseline was associated with a 11.0% increase in odds of membership in the most favorable mortality trajectory groups. Counties with less favorable trajectories demonstrated higher poverty rates, unemployment, and greater percentages of Black residents, with some experiencing PCP supply declines up to 20.1% over the study period.

This study provides novel evidence that sustained primary care physician supply is associated with more favorable long-term mortality trajectories at the county level. Counties with persistently low PCP supply-which disproportionately serve communities of color and economically disadvantaged populations-experienced the worst mortality outcomes. These findings underscore the critical role of primary care in addressing health disparities and suggest that policies enhancing primary care access, particularly in underserved areas, could significantly improve population health equity. Comprehensive interventions addressing both primary care workforce distribution and social determinants of health are essential for equitable health outcomes.