Geospatial Analysis of Social Vulnerability, Race, and Firearm Violence in Chicago.

INTRODUCTION

Urban firearm violence (UFV) is associated with inequities rooted in structural racism and socioeconomic disparities. Social vulnerability index (SVI) is a composite measure that encompasses both. We sought to understand the relationship between SVI and the incidence of UFV in Chicago using geospatial analysis for the first time.

MATERIALS AND METHODS

Firearm assaults in Chicago 2001-2019 were obtained from the Trace. Locations of incidents were geocoded using ArcGIS and overlaid with census tract vector files. These data were linked to 2018 SVI measures obtained from the Center for Disease Control and Prevention. Shooting rates were calculated by tabulating the total number of shootings per capita in each census tract. We used Poisson regression with robust error variance to estimate the incident rate of UFV in different levels of social vulnerability and Local Moran's I to evaluate spatial autocorrelation.

RESULTS

In total, 642 census tracts were analyzed. The median shooting rate was 2.6 per 1000 people (interquartile 0.77, 7.0). When compared to those census tracts with very low SVI, census tracts with low SVI had a 1.7-time increased incident rate of shootings (incidence rate ratio [IRR] 1.74, 95% CI 1.08, 2.81), tracts with moderate SVI had a 3.1-time increased incident rate (IRR 3.07, 95% CI 2.31, 4.10), and tracts with high SVI had a 7-time increased incident rate (IRR 7.03, 95% CI 5.45, 9.07).

CONCLUSIONS

In Chicago, social vulnerability has a significant association with rates of firearm violence, providing a focus point for policy intervention to address high rates of interpersonal violence in similar cities.