Association of community-level inequities and premature mortality: Chicago, 2011-2015

Background Substantial disparities in life expectancy exist between Chicago's 77 defined community areas, ranging from approximately 69 to 85 years. Prior work in New York City and Boston has shown that community-level racial and economic segregation as measured by the Index of Concentration at the Extremes (ICE) is strongly related to premature mortality. This novel metric allows for the joint assessment of area-based income and racial polarisation. This study aimed to assess the relationships between racial and economic segregation and economic hardship with premature mortality in Chicago. Methods Annual age-adjusted premature mortality rates (deaths <65 years) from 2011 to 2015 were calculated for Chicago's 77 community areas. ICE measures for household income (<US25 000 vs ≥US100 000), race (black vs non-Hispanic white), combined ICE measure incorporating income and race, and hardship index were calculated from 2015 American Community Survey 5-year estimates. Results Average annual premature mortality rates ranged from 94 (95% CI 61 to 133) deaths per 100 000 population age <65 to 699 (95% CI 394 to 1089). Compared with the highest ICE quintiles, communities in the lowest quintiles had significantly higher rates of premature mortality (ICE Income rate ratio (RR)=3.06, 95% CI 2.51 to 3.73; ICE Race RR=3.07, 95% CI 2.62 to 3.58; ICE Income+Race RR=3.27, 95% CI 2.84 to 3.77). Similarly, compared with communities in the lowest hardship index quintile, communities in the highest quintile had significantly higher premature mortality rates (RR=2.79, 95% CI 2.18 to 3.57). Conclusions The strong relationships observed between ICE measures and premature mortality - particularly the combined ICE metric encompassing race and income - support the use of ICE in public health monitoring.