Strict state firearm policies are associated with significantly lower rates of suicide and homicide compared with states with more lenient legislation, according to findings from a cross-sectional analysis published in JAMA Internal Medicine.

Investigators evaluated the rates of firearm, non-firearm, and total homicide and suicide deaths in 3108 counties in the 48 contiguous states, using data obtained from the US Centers for Disease Control and Prevention (CDC) for firearm suicide and homicide decedents. Specifically, the investigators compared incidence rates between groups of counties and a reference group, as well as counties with high home state and interstate policies. States with restrictive gun policies typically had laws requiring a license to purchase firearms, background checks for private sales, restriction of multiple firearm sales, and reporting loss or stolen firearms. The interstate policy score was calculated for each county included in this analysis, with a range of -1.33 to 8.31 (higher scores: stricter legislation in nearby states).

Overall, strong state firearm laws were associated with significantly lower firearm-related suicide rates as well as lower overall suicide rates. Conversely, states with lax or more lenient state firearm laws demonstrated higher firearm-related suicide rates. Similar rates were observed across levels of interstate policy score (low: incidence rate ratio [IRR] 1.34; 95% CI, 1.11-1.65; medium: IRR 1.36, (95% CI, 1.15-1.65; and high: IRR 1.43; 95% CI, 1.20-1.73).

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Higher homicide rates in counties were associated with a higher percentage of households receiving public assistance (2.54% [range 0.00-24.83]), a higher percentage of black (8.94% [range 0.00-85.91]) or Hispanic (8.69% [range 0.00-95.68]) residents, a greater number of households headed by women (16.93% [range 0.00 to 52.09]), and a higher percentage of residents age ≥25 who did not complete high school (15.06% [range 1.27 to 53.28]).

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The counties featuring low state and low or medium interstate policy scores demonstrated the highest rates of firearm-related homicide (IRR 1.38; 95% CI, 1.02-1.88) and higher overall rates of homicide (IRR 1.32; 95% CI, 1.03-1.67). In the event of high interstate firearm policies in states with low firearm policy scores, counties in these states had lower firearm-related homicides.

Due to the study’s cross-sectional design, the investigators were unable to determine a association between firearm state policies and firearm deaths. Also, the investigators did not adjust for municipalities that had stronger firearm restrictions than the states in which they resided.

Findings from this analysis support “strengthening state firearm policies to reduce the incidence of both firearm suicide and homicide, with benefits that may extend across state lines.”


Kaufman EJ, Morrison CN, Branas CC, Wiebe DJ. State firearm laws and interstate firearm deaths from homicide and suicide in the United States: A cross-sectional analysis of data by county [published online March 5, 2018]. JAMA Intern Med. doi:10.1001/jamainternmed.2018.0190.