Variation in youth and young adult homicide rates and their association with city characteristics in Latin America: the SALURBAL studyResearch in context

Summary: Background: Latin America and the Caribbean (LAC) is one of the most urbanized and violent regions worldwide. Homicides in youth (15–24 years old, yo) and young adults (25-39yo) are an especially pressing public health problem. Yet there is little research on how city characteristics relate to homicide rates in youth and young adults. We aimed to describe homicide rates among youth and young adults, as well as their association with socioeconomic and built environment factors across 315 cities in eight LAC countries. Methods: This is an ecological study. We estimated homicide rates in youth and young adults for the period 2010–2016. We investigated associations of homicide rates with sub-city education and GDP, Gini, density, landscape isolation, population and population growth using sex-stratified negative binomial models with city and sub-city level random intercepts, and country-level fixed effects. Findings: The mean sub-city homicide rate per 100,000 in persons aged 15–24 was 76.9 (SD = 95.9) in male and 6.7 (SD = 8.5) in female, and in persons aged 25–39 was 69.4 (SD = 68.9) in male and 6.0 (SD = 6.7) in female. Rates were higher in Brazil, Colombia, Mexico and El Salvador than in Argentina, Chile, Panama and Peru. There was significant variation in rates across cities and sub-cities, even after accounting for the country. In fully adjusted models, higher sub-city education scores and higher city GDP were associated with a lower homicide rate among male and female (rate ratios (RR) per SD higher value in male and female, respectively, 0.87 (CI 0.84–0.90) and 0.90 (CI 0.86–0.93) for education and 0.87 (CI 0.81–0.92) and 0.92 (CI 0.87–0.97) for GDP). A higher city Gini index was associated with higher homicide rates (RR 1.28 (CI 1.10–1.48) and 1.21 (CI 1.07–1.36) in male and female, respectively). Greater isolation da was also associated with higher homicide rates (RR 1.13 (CI 1.07–1.21) and 1.07 (CI 1.02–1.12) in male and female, respectively). Interpretation: City and sub-city factors are associated with homicide rates. Improvements to education, social conditions and inequality and physical integration of cities may contribute to the reduction of homicides in the region. Funding: The Wellcome Trust [205177/Z/16/Z].