Importance: Firearm injury is the second leading cause of death in the United States for children and young adults. The risk of unintentional and self-inflicted firearm injury is lower when all household firearms are stored locked.
Objective: To estimate the reduction in youth firearm suicide and unintentional firearm mortality that would result if more adults in households with youth stored household guns locked.
Design, setting, and participants: A modeling study using Monte Carlo simulation of youth firearm suicide and unintentional firearm mortality in 2015. A simulated US national sample of firearm-owning households where youth reside was derived using nationally representative rates of firearm ownership and storage and population data from the US Census to test a hypothetical intervention, safe storage of firearms in the home, on youth accidental death and suicide. Data analyses were performed from August 3, 2017, to January 9, 2018.
Exposures: Observed and counterfactual household-level safe firearm storage (ie, storing all firearms locked), the latter estimated by varying the probability that a hypothetical intervention increased safe firearm storage beyond that observed in 2015.
Main outcomes and measures: Observed and counterfactual counts of firearm suicide and unintentional firearm mortality among youth aged 0 to 19 years, the latter estimated by incorporating an empirically based estimate of the mortality benefit expected from additional safe storage (beyond that observed in 2015).
Results: A hypothetical intervention among firearm owners residing with children with a 20% probability of motivating these owners to lock all household firearms was significantly associated with a projected reduction in youth firearm mortality (median incidence rate ratio = 0.90; interquartile range, 0.87-0.93). In the overall model, 6% to 32% of deaths were estimated to be preventable depending on the probability of motivating safer storage.
Conclusions and relevance: Results of this modeling study suggest that a relatively modest uptake of a straightforward safe storage recommendation-lock all household firearms-could result in meaningful reductions in firearm suicide and unintentional firearm fatalities among youth. Approaches that will motivate additional parents to store firearms safely are needed.