Importance: Suicide by firearm is a major cause of mortality in young Missouri residents. Changes in statewide firearm policy may have contributed to changes in suicide rates.
Objective: To evaluate if changes in Missouri permit-to-purchase (PTP) and concealed carry firearm laws were associated with changes in rates of suicide by firearms in young Missouri residents.
Design, settings, and participants: This cross-sectional study examined rates of suicide by firearm in Missouri among adolescents (ages 14-18 years) and young adults (ages 19-24 years) from January 1999 to December 2018, following changes to state PTP and concealed carry law, in comparison with a donor state pool with existing firearm laws (13 states in PTP pool; 42 states in concealed carry pool) that did not make changes during this period. This study used a quasiexperimental, synthetic control design at the state level that defined Missouri as the treated state and treatment as changes in firearm laws.
Exposures: Legislative changes to Missouri's PTP and concealed carry firearm laws.
Main outcomes and measures: Age-adjusted annual rates of firearm-related suicide mortality per 100 000 people for adolescents (aged 14-18 years) and young adults (aged 19-24 years).
Results: Repeal of the PTP law was associated with a 21.8% increase in firearm suicide rates in young adults aged 19 to 24 years in Missouri. Lowering the minimum age of concealed carry to 19 years in Missouri was associated with a 32.0% increase in firearm suicide rates and a 29.7% increase in nonfirearm suicide rates in adolescents aged 14 to 18 years, and a 7.2% increase in firearm suicide rates in young adults aged 19 to 24 years.
Conclusions and relevance: Increases in rates of suicide by firearms in adolescents and young adults were seen following repeal of Missouri's PTP law and lowering of the minimum age for concealed carry in 2014. Changes in Missouri's firearm policies may be an important contributor to rates of suicide by firearm in young Missouri residents.