In-State and Interstate Associations Between Gun Shows and Firearm Deaths and Injuries: A Quasi-experimental Study.

Background Gun shows are an important source of firearms, but no adequately powered studies have examined whether they are associated with increases in firearm injuries. Objective To determine whether gun shows are associated with short-term increases in local firearm injuries and whether this association differs by the state in which the gun show is held. Design Quasi-experimental. Setting California. Participants Persons in California within driving distance of gun shows. Measurements Gun shows in California and Nevada between 2005 and 2013 (n = 915 shows) and rates of firearm-related deaths, emergency department visits, and inpatient hospitalizations in California. Results Compared with the 2 weeks before, postshow firearm injury rates remained stable in regions near California gun shows but increased from 0.67 injuries (95% CI, 0.55 to 0.80 injuries) to 1.14 injuries (CI, 0.97 to 1.30 injuries) per 100 000 persons in regions near Nevada shows. After adjustment for seasonality and clustering, California shows were not associated with increases in local firearm injuries (rate ratio [RR], 0.99 [CI, 0.97 to 1.02]) but Nevada shows were associated with increased injuries in California (RR, 1.69 [CI, 1.16 to 2.45]). The pre-post difference was significantly higher for Nevada shows than California shows (ratio of RRs, 1.70 [CI, 1.17 to 2.47]). The Nevada association was driven by significant increases in firearm injuries from interpersonal violence (RR, 2.23 [CI, 1.01 to 4.89]) but corresponded to a small increase in absolute numbers. Nonfirearm injuries served as a negative control and were not associated with California or Nevada gun shows. Results were robust to sensitivity analyses. Limitation Firearm injuries were examined only in California, and gun show occurrence was not randomized. Conclusion Gun shows in Nevada, but not California, were associated with local, short-term increases in firearm injuries in California. Differing associations for California versus Nevada gun shows may be due to California's stricter firearm regulations. Primary Funding Source National Institutes of Health; University of California, Berkeley; and Heising-Simons Foundation.