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American firearm homicides

The impact of your neighbors

Olson, Erik J., MD; Hoofnagle, Mark, MD; Kaufman, Elinore J., MD; Schwab, Charles William, MD; Reilly, Patrick M., MD; Seamon, Mark J., MD

Journal of Trauma and Acute Care Surgery: May 2019 - Volume 86 - Issue 5 - p 797–802
doi: 10.1097/TA.0000000000002212
EAST Journal Club

BACKGROUND Restrictive firearm legislation has correlated with decreased overall firearm fatality rates, but not with firearm-related homicide or firearm mortality among Black Americans. We hypothesized that firearm trafficking from states with less restrictive firearm legislation to neighboring states with more restrictive firearm legislation increases firearm homicide rates in those restrictive states.

METHODS For years 2011–2015, state firearm legislation Brady Campaign to Prevent Gun Violence scorecards were analyzed in relation to firearms traced by the Bureau of Alcohol, Tobacco, and Firearms and Center for Disease Control and Prevention firearm mortality rates. States were ranked by Brady score and arranged by quintile to establish the Standardized Brady Score. The effect of less-restrictive neighboring states on the 10 most-restrictive firearm legislation states was modeled by averaging the 10 most-restrictive states with their bordering states to create a Border Adjustment Score. Firearm fatality rates were calculated for each quintile and Poisson regression models were created for each score and outcome. Model fit was compared using Akaike Information Criterion (AIC).

RESULTS There were 169,396 firearm fatalities including 57,885 firearm homicides. Comparing top and bottom quintile firearm legislation states, 65% vs. 44% of firearms traced by the Bureau of Alcohol, Tobacco, Firearms and Explosives originated in other states respectively. The Border Adjustment Score generated a more linear relationship than the Standardized Brady Score for all firearm fatality categories as firearm legislation scores decreased. The Border Adjustment Score minimized the AIC with respect to the Standardized Brady Score for black (AIC, 4443 vs. 4680) and white firearm homicide rates (3243 vs. 4319), indicating improved model fit after adjustment for neighboring state firearm legislation.

CONCLUSION Our results suggest that firearm movement across states plays an important role in firearm homicides. Accounting for firearm legislation in both individual and neighboring states may improve our understanding of the relationship between firearm legislation and homicide.

LEVEL OF EVIDENCE Prognostic and epidemiological study, level IV.

From the Division of Traumatology, Surgical Critical Care and Emergency Surgery, Perelman School of Medicine, University of Pennsylvania Health System, Philadelphia, Pennsylvania.

Submitted: October 15, 2018, Revised: January 24, 2019, Accepted: January 26, 2019, Published online: February 8, 2019.

This paper was presented as a Quick-Shot Presentation at 77th Annual Meeting of the American Association for the Surgery of Trauma Conference, September 29, 2017, San Diego, CA.

Address for reprints: Erik J. Olson, MD, Perelman School of Medicine, University of Pennsylvania Health System, Division of Traumatology, Surgical Critical Care and Emergency Surgery, 1st Floor, Medical Office Bldg, Suite 120, 51 North 39th St, Philadelphia, PA 19104l; email:

© 2019 Lippincott Williams & Wilkins, Inc.