Investigating the effect of social changes on age-specific gun-related homicide rates in New York City during the 1990s

Objectives. We assessed whether New York City's gun-related homicide rates in the 1990s were associated with a range of social determinants of homicide rates. Methods. We used cross-sectional time-series data for 74 New York City police precincts from 1990 through 1999, and we estimated Bayesian hierarchical models with a spatial error term. Homicide rates were estimated separately for victims aged 15-24 years (youths), 25-34 years (young adults), and 35 years or older (adults). Results. Decreased cocaine consumption was associated with declining homicide rates in youths (posterior median [PMJ=0.25; 95% Bayesian confidence interval [BCI]=0.07, 0.45) and adults (PM=0.07; 95% BCI=0.02, 0.12), and declining alcohol consumption was associated with fewer homicides in young adults (PM=0.14; 95% BCI=0.02, 0.25). Receipt of public assistance was associated with fewer homicides for young adults (PM =-104.20; 95% BCI=-182.0, -26.14) and adults (PM=-28.76; 95% BCI=-52.65, -5.01). Misdemeanor policing was associated with fewer homicides in adults (PM =-0.01; 95% BCI=-0.02, -0.001). Conclusions. Substance use prevention policies and expansion of the social safety net may be able to cause major reductions in homicide among age groups that drive city homicide trends.