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BMJ. 2019 Mar 6;364:l542. doi: 10.1136/bmj.l542.

State gun laws, gun ownership, and mass shootings in the US: cross sectional time series.

Author information

1
Department of Epidemiology, Columbia University, Mailman School of Public Health, 722 West 168th Street, New York, NY 10032, USA pmr2149@cumc.columbia.edu.
2
Department of Population Health, New York University, Langone School of Medicine, New York, NY, USA.
3
Department of Community Health Sciences, Boston University School of Public Health, Boston, MA, USA.
4
Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.
5
Boston University School of Public Health, Boston, MA, USA.
6
Department of Epidemiology, Columbia University, Mailman School of Public Health, 722 West 168th Street, New York, NY 10032, USA.

Abstract

OBJECTIVE:

To determine whether restrictiveness-permissiveness of state gun laws or gun ownership are associated with mass shootings in the US.

DESIGN:

Cross sectional time series.

SETTING AND POPULATION:

US gun owners from 1998-2015.

EXPOSURE:

An annual rating between 0 (completely restrictive) and 100 (completely permissive) for the gun laws of all 50 states taken from a reference guide for gun owners traveling between states from 1998 to 2015. Gun ownership was estimated annually as the percentage of suicides committed with firearms in each state.

MAIN OUTCOME MEASURE:

Mass shootings were defined as independent events in which four or more people were killed by a firearm. Data from the Federal Bureau of Investigation's Uniform Crime Reporting System from 1998-2015 were used to calculate annual rates of mass shootings in each state. Mass shooting events and rates were further separated into those where the victims were immediate family members or partners (domestic) and those where the victims had other relationships with the perpetrator (non-domestic).

RESULTS:

Fully adjusted regression analyses showed that a 10 unit increase in state gun law permissiveness was associated with a significant 11.5% (95% confidence interval 4.2% to 19.3%, P=0.002) higher rate of mass shootings. A 10% increase in state gun ownership was associated with a significant 35.1% (12.7% to 62.7%, P=0.001) higher rate of mass shootings. Partially adjusted regression analyses produced similar results, as did analyses restricted to domestic and non-domestic mass shootings.

CONCLUSIONS:

States with more permissive gun laws and greater gun ownership had higher rates of mass shootings, and a growing divide appears to be emerging between restrictive and permissive states.

PMID:
30842105
PMCID:
PMC6402045
DOI:
10.1136/bmj.l542
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organization for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

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