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

Correspondence to Dr Brittney S Lange-Maia, Department of Preventive Medicine and Center for Community Health Equity, Rush University Medical Center, Chicago, IL 60612, USA; [email protected]

Introduction

Life expectancy at birth in Chicago is approximately 76.9 years, slightly under the national average life expectancy of roughly 78.7 years.^{1 2} Disparities are evident when examining life expectancy between racial/ethnic groups in Chicago—ranging from 71.7 years for black residents, 78.8 years for non-Hispanic white residents, to 84.6 years for Hispanic and Latino residents.² Disparities are also pronounced between Chicago’s 77 officially designated communities (which have been used to study the city’s social inequalities since the 1920s³) with a gap of nearly 15 years existing between the communities with the highest (83 years) and lowest (68 years) life expectancy.² Undoubtedly, localised data are important for identifying communities and populations in greatest need for interventions.

The national trend is towards a small decline in black–white segregation in many US cities; however, the Chicago metropolitan area remains starkly segregated by race.^{4 5} Prior work in Chicago has shown a strong relationship between community-level racial/ethnic make-up and health outcomes, with communities of predominantly black residents having higher rates of diabetes-related and stroke-related mortality, low birth weight and maternal smoking.^6–9 Community-level income has also been extensively related to health, with many communities of colour having lower income (and worse health outcomes) compared with higher-income, predominantly white communities.^{2 6–8 10} Prior studies in this area have largely looked at only ‘one end of the spectrum’—disadvantage—without considering the distribution of affluence in the city.¹¹ A limitation to examining community-level racial make-up or median household income is that they do not capture the unequal distribution of income and race across communities. Accounting for the distribution of affluence and poverty, rather than poverty alone, is important for understanding the spatial distribution of health outcomes.

Recently, the Index of Concentration at the Extremes (ICE)¹² has been incorporated into the public health literature to relate health outcomes with area-level spatial social polarisation, particularly with regard to race and income.^13–15 For example, in New York City and Boston, an ICE measure that incorporates both area-level income and race was more strongly associated with premature mortality and infant mortality...