Firearm legislation and firearm-related fatalities in the United States.

IMPORTANCE: Over 30,000 people die annually in the United States from injuries caused by firearms. Although most firearm laws are enacted by states, whether the laws are associated with rates of firearm deaths is uncertain.

OBJECTIVE: To evaluate whether more firearm laws in a state are associated with fewer firearm fatalities.

DESIGN: Using an ecological and cross-sectional method, we retrospectively analyzed all firearm-related deaths reported to the Centers for Disease Control and Prevention Web-based Injury Statistics Query and Reporting System from 2007 through 2010. We used state-level firearm legislation across 5 categories of laws to create a "legislative strength score," and measured the association of the score with state mortality rates using a clustered Poisson regression. States were divided into quartiles based on their score.

SETTING: Fifty US states.

PARTICIPANTS: Populations of all US states.

MAIN OUTCOME MEASURES: The outcome measures were state-level firearm-related fatalities per 100,000 individuals per year overall, for suicide, and for homicide. In various models, we controlled for age, sex, race/ethnicity, poverty, unemployment, college education, population density, nonfirearm violence-related deaths, and household firearm ownership.

RESULTS: Over the 4-year study period, there were 121,084 firearm fatalities. The average state-based firearm fatality rates varied from a high of 17.9 (Louisiana) to a low of 2.9 (Hawaii) per 100,000 individuals per year. Annual firearm legislative strength scores ranged from 0 (Utah) to 24 (Massachusetts) of 28 possible points. States in the highest quartile of legislative strength (scores of ≥9) had a lower overall firearm fatality rate than those in the lowest quartile (scores of ≤2) (absolute rate difference, 6.64 deaths/100,000/y; age-adjusted incident rate ratio [IRR], 0.58; 95% CI, 0.37-0.92). Compared with the quartile of states with the fewest laws, the quartile with the most laws had a lower firearm suicide rate (absolute rate difference, 6.25 deaths/100,000/y; IRR, 0.63; 95% CI, 0.48-0.83) and a lower firearm homicide rate (absolute rate difference, 0.40 deaths/100,000/y; IRR, 0.60; 95% CI, 0.38-0.95).

CONCLUSIONS AND RELEVANCE: A higher number of firearm laws in a state are associated with a lower rate of firearm fatalities in the state, overall and for suicides and homicides individually. As our study could not determine cause-and-effect relationships, further studies are necessary to define the nature of this association.