The recent mass shooting in Las Vegas, Nevada, was a painful reminder that injuries and deaths resulting from access to guns continue to bedevil many parts of U.S. society, including communities; the health care industry; and the families of those injured, killed, or threatened by firearms. Although the problem created by more than 300 million guns in the United States will ultimately need a political solution, science and scientific publications have important roles in assessing and promoting awareness about interventions that may reduce the 36 000 fatal and 85 000 nonfatal firearm injuries each year (1).
The lack of meaningful action by Congress has left states to chip away in myriad ways at reducing access to guns by those likely to use them for harm against themselves or others. Several studies have shown an inverse association between the stringency of state legislation to restrict firearm access and the rate of firearm injuries and deaths (2). However, our knowledge about the effect of policies regulating gun shows on firearm morbidity and mortality is severely limited.
Matthay and colleagues (3) examined the association between gun shows occurring separately in California and Nevada and short-term changes in the rates of fatal and nonfatal firearm injuries in California regions exposed to those shows. Gun shows account for only a small proportion of private-party firearm transfers; nevertheless, they can be a source of guns used in crime (4). Gun shows allow both licensed dealers and unlicensed persons to sell firearms to attendees. Whereas purchases from federally licensed dealers require a background check of the potential buyer before a sale is made, several states do not require these checks in private-party sales, as was the case in Nevada during Matthay and colleagues' study period. In California, on the other hand, firearm transfers at shows must be processed through a licensed dealer (5). Thus, the concern was raised that California residents can simply drive over the state line and purchase guns at a Nevada show without any background check or waiting period.
Matthay and colleagues compared the rates of firearm injuries in the 2 weeks after and before gun shows among California residents within convenient driving distance of shows in Nevada versus California. Their analysis accounted for California's 10-day waiting period between purchasing and obtaining a gun. Comparing California regions exposed to Nevada shows with those exposed to California shows, the ratios of after–before rate ratios were 1.70 (95% CI, 1.17 to 2.47) for all-intent firearm injuries and 2.23 (CI, 1.01 to 4.90) for interpersonal firearm injuries. This ratio was mainly driven by changes in firearm injuries after Nevada shows. Whereas firearm injuries of any intent did not change meaningfully among California regions exposed to California gun shows, the rate of interpersonal firearm injuries increased significantly among California regions exposed to Nevada shows. However, as the authors note, the difference in absolute rates of firearm injuries was small: an overall increase from 0.67 to 1.14 injuries per 100 000 California residents exposed to Nevada shows.
The authors should be commended for using various strategies, including negative control analysis and quantitative bias analysis, to gauge their findings' sensitivity to assumptions and robustness to potential confounding. These approaches are important, especially considering the differences between California regions exposed to California versus Nevada shows. Table 2 of the article shows notable differences between the absolute rates of firearm injuries before shows in those 2 types of region: In regions exposed to California shows, the rate of interpersonal firearm injuries was greater than that of each other type of firearm injury, whereas in regions exposed to Nevada shows, the rate of unintentional firearm injuries was highest. As such, unmeasured differences might exist between those 2 California regions that can influence short-term changes in the rates of firearm injuries after gun shows. A limitation of the study, as acknowledged by authors, is that firearm injuries were not examined among Nevada residents themselves. If unregulated gun shows increase firearm injuries in the short term, one may expect to see such an association among Nevada residents exposed to shows in that state.
The data in Matthay and colleagues' study may suggest some association between gun shows and self-directed and unintentional firearm injuries, but the estimates (that is, about 50% to 60% relative increase) were not statistically significant. It is often forgotten that about two thirds of firearm deaths in the United States are suicides. A prior study by Wintemute and colleagues showed that purchasers of a handgun had a 57-fold and 7-fold increased risk for firearm suicide in the first week and first year, respectively, after purchase (6). Evidence indicates that the means available to commit self-harm matter and that restricting the most lethal means (that is, firearms) can prevent the loss of lives due to suicide (7). Also, future research should examine whether gun shows affect unintentional firearm injuries, and if so, what plausible explanations might exist.
The study by Matthay and colleagues has many implications for gun policy in the United States. Laws regulating access to guns matter and do make a difference, especially collectively (2); however, their impact on an individual basis is a somewhat small chip in the granite wall of firearm injuries and deaths. The state-by-state nature of these laws, due to the lack of federal legislation, results in barriers to gun access that can be easily breached by a car trip. It does not reduce the importance of the laws but does reduce their impact.
Unfortunately, the amount of research on firearms is disproportionately low compared with the burden they impose on health care and society as a whole. In 1996, Congress inserted language into the Centers for Disease Control and Prevention appropriation bills that essentially prevented it from conducting and funding firearm-related research (8, 9); this lack of funding continues to this day. Nevertheless, the public health burden of firearm-related injuries and death demands that research on interventions to reduce this toll be continued, funded by local and state governments, foundations, and philanthropy.
References
- Centers for Disease Control and Prevention; National Center for Injury Prevention and Control. Web-based Injury Statistics Query and Reporting System (WISQARS). Accessed at www.cdc.gov/injury/wisqars on 3 October 2017.
- Santaella-TenorioJCerdáMVillavecesAGaleaSWhat do we know about the association between firearm legislation and firearm-related injuries?Epidemiol Rev20163814057PubMed
- MatthayECGalinJRudolphKEFarkasKWintemuteGJAhernJIn-state and interstate associations between gun shows and firearm deaths and injuries. A quasi-experimental study.Ann Intern Med2017. [Epub ahead of print]
- Wintemute G. Background Checks for Firearm Transfers. Violence Prevention Research Program, University of California, Davis; 2013. Accessed at www.ucdmc.ucdavis.edu/vprp/CBC%20White%20Paper%20Final%20Report%20022013.pdf on 3 October 2017.
- Law Center to Prevent Gun Violence. Gun Shows in California. 2016. Accessed at http://smartgunlaws.org/gun-shows-in-california on 3 October 2017.
- Department of Health and Human Services Appropriations Act, Pub. L. No. 104-208, 110 Stat. 1996. Accessed at www.congress.gov/104/plaws/publ208/PLAW-104publ208.pdf on 11 October 2017.