County Poverty Concentration and Disparities in Unintentional Injury Deaths: A Twelve Year Analysis of 1.3 Million U.S. Fatalities

Background: Unintentional injury is the fifth leading cause of death in the United States, and mortality due to injury has risen over the past decade. The social determinants behind these rising trends are not well understood. This study examines the association between county-level poverty and unintentional injury mortality in the US from 1999-2010, overall and by six specific mechanisms.

Methods: Annual compressed mortality and population data for 1999-2010 were linked with census county poverty measures. We calculated age-adjusted mortality rates and time trends for county poverty categories, and used multivariate negative binomial regression to determine the relative risk of living in high poverty concentration areas and the population attributable fraction.

Results: Age-adjusted mortality rates show that counties with > 20% poverty had a 66% higher rate of injury mortality in 1999 than counties with < 5% poverty (45.25 vs. 27.24 per 100,000), and that gap widened in 2010 to 89% (44.85 vs. 23.76). The disparity in poisoning deaths increased the greatest over the twelve year period. The population attributable fraction for all unintentional injuries rose from 0.22 in 1999 to 0.40 in 2010, accounting for nearly 400,000 deaths that would not have occurred if all counties had the same risk as those with low poverty concentrations.

Conclusions: Prior studies have demonstrated the deleterious effect of neighborhood poverty on health. Our study shows that county-level poverty confers a greater risk of death from injury, and that higher poverty concentration areas shoulder the burden of increased injury mortality.