Changes in the Age Profile of Chicago Gun Homicide Decedents: Violent Death Surveillance 2015-2021 (Preprint)

BACKGROUND Background The US gun-related homicide rate 24.9 is times that of the world’s 28 most populous high-income countries combined. Within the US, Chicago’s gun-related homicide rate is even higher, at 22.65 per 100,000 persons, four times the US rate of 5.9 gun-related homicides per 100,000 persons. OBJECTIVE The objective of this study is to use homicide surveillance data to determine the age distribution of gun-related homicide decedents and the distribution of gun-related homicide rates by age-group to ascertain if age distribution is constant over time. METHODS We calculated gun-related homicide rates by age using US Census population estimates in the denominator and the number of deaths by age-group in the numerator. The quotient is multiplied by 100,000 to standardize rates. We generate the age-group distribution of gun-related homicide rates by race/ethnicity and sex. To assess variation in gun-related homicide rates overall and among race/ethnic groups, and race/ethnic groups over time, we use an F-test in one-way analysis of variance (ANOVA) with significance set at p<0.05. We use Pearson’s correlation coefficient to understand the strength of the relationship between age and gun-related homicide. We ran 12 multivariate regression models to assess change over time in gun-related homicide rates by age group with significance set at P<0.05. RESULTS Between 2015 and 2021, there were 3724 gun-related homicides in Chicago; 87.1% Non-Hispanic (NH) Black; 92% male. Since 2015, gun-related homicide rates have increased by 58% in Chicago. The mean age of gun-related homicide decedents increased by 3.27 years. The mean age for non-Hispanic (NH) White decedents is seven years higher than that of NH Black and Latinx decedents. Age-group patterns in the number of gun-related homicides have changed since 2019 with 25 to 29-year-olds surpassing that of 20-24-year-olds, and 30-34-year-olds surpassing that of 15-19-year-olds upending established patterns. Gun-related homicide rates have increased significantly over time for 30 to 34, 40 to 44 and 45 to 49-year-olds. CONCLUSIONS Between 2015 and 2021, there were 3724 gun-related homicides in Chicago; 87.1% Non-Hispanic (NH) Black; 92% male. Since 2015, gun-related homicide rates have increased by 58% in Chicago. The mean age of gun-related homicide decedents increased by 3.27 years. The mean age for non-Hispanic (NH) White decedents is seven years higher than that of NH Black and Latinx decedents. Age-group patterns in the number of gun-related homicides have changed since 2019 with 25 to 29-year-olds surpassing that of 20-24-year-olds, and 30-34-year-olds surpassing that of 15-19-year-olds upending established patterns. Gun-related homicide rates have increased significantly over time for 30 to 34, 40 to 44 and 45 to 49-year-olds.