Association of Drug and Alcohol Use With Adolescent Firearm Homicide at Individual, Family, and Neighborhood Levels.

Importance: Homicide is the third leading cause of death for adolescents in the United States and the leading cause of death for adolescents who are African American. Large cities have disproportionate homicide rates.

Objective: To determine the relationships between exposures to drugs and alcohol at the individual, family, and neighborhood levels and adolescent firearm homicide and to inform new approaches to preventing firearm violence.

Design, Setting, And Participants: Population-based case-control study from January 2010 to December 2012 of all 13- to 20-year-olds who were homicide victims in Philadelphia during the study period matched to randomly selected 13- to 20-year-old controls from the general population.

Exposures: Individual drug and alcohol use at the time of injury, history of drug and alcohol use, caregiver drug and alcohol use, and neighborhood availability of alcohol and illegal drugs. We also controlled for age, race, school suspensions, arrests, and neighborhood ethnicity.

Main Outcomes And Measures: Adolescent firearm homicide identified from police and medical examiner's reports.

Results: We enrolled 161 adolescent homicide cases, including 157 (97.5%) firearm homicide cases and 172 matched controls, including 166 (96.5%) firearm homicide controls. Adolescents with a history of alcohol use (adjusted odds ratio [AOR], 4.1; 95% CI, 1.2-14.0) or drug use (AOR, 4.4; 95% CI, 1.7-11.6) had increased odds of firearm homicide. Adolescents whose caregiver had a history of drug use had increased odds of firearm homicide (AOR, 11.7; 95% CI, 2.8-48.0). Adolescents in neighborhoods with high densities of alcohol outlets (AOR, 3.2; 95% CI, 1.1-9.1) and moderate or high drug availability had increased odds of firearm homicide (AOR, 3.4; 95% CI, 1.1-10.3 vs AOR, 7.5; 95% CI, 2.2-25.8).

Conclusions And Relevance: Almost all adolescent homicides in Philadelphia between 2010 and 2012 were committed with a firearm. Substance use at the individual, family, and neighborhood levels was associated with increased odds of adolescent firearm homicide; drug use was associated at all 3 levels and alcohol at the individual and neighborhood levels. Expanding violence prevention efforts to target drug and alcohol use at multiple levels may help to reduce the firearm violence that disproportionately affects adolescents in minority populations in large US cities.