State firearm laws and nonfatal firearm injury-related inpatient hospitalizations: A nationwide panel study.

Background: Firearm injury remains a major cause of morbidity and mortality in the United States. Because of prior lack of comprehensive data sources, there is a paucity of literature on nonfatal firearm injury. Associations have previously been shown between state-level firearm laws and firearm fatalities, but few studies have examined the effects of these laws on nonfatal firearm hospitalization rates. Our objective was to examine the relationship between state firearm laws and firearm injury-related hospitalization rates across all 50 states over a 17-year period.
Methods: In this panel study design, we used fixed effects multivariate regression models to analyze the relationship between 12 laws and firearm state-level injury-related hospitalization rates from 2000 to 2016 using the RAND Corporation Inpatient Hospitalizations for Firearm Injury Database. We used difference-in-differences to determine the impact of law passage in a given state compared with those states without the law, controlling for state-level covariates. The main outcome measure was the change in annual firearm injury-related inpatient hospitalization rates after passage or repeal of a state-level firearm law.
Results: Examining each law individually, passage of violent misdemeanor, permitting, firearm removal from domestic violence offenders, and 10-round limit laws were associated with significant firearm injury-related hospitalization rate reductions. Examining multiple laws in the same model, passage of violent misdemeanor laws was associated with a 19.9% (confidence interval, 11.6%-27.4%) reduction, and removal of firearms from domestic violence offenders was associated with a 17.0% (confidence interval, 9.9%-23.6%) reduction in hospitalization rates.
Conclusion: State laws related to preventing violent offenders from possessing firearms are associated with firearm injury-related hospitalization rate reductions. Given significant physical, mental, and social burdens of nonfatal firearm injury, determining the efficacy of firearm-related policy is critical to violence and injury prevention efforts.
Level of Evidence: Prognostic and Epidemiologic; Level IV.
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