Examining the policy effects of Arizona's 2016 pre-emption law on firearm suicide rates in the greater Tucson area: an observational study

Abstract

Objective: In 2016, Arizona enacted SB 1487 to nullify Tucson's ordinance permitting the municipality to destroy confiscated and forfeited firearms and instead require the firearms to be resold to the public through an auctioneer. Our objective was to examine whether firearm suicide rates increased in Pima County (greater Tucson area) relative to other Arizona counties following the enactment of Arizona's 2016 pre-emption law.

Design: An observational study of a natural policy experiment. We used a difference-in-differences approach to estimate the effects of Arizona enacting SB 1487 on firearm suicide rates in Pima County. Our statistical analyses adjusted for county-level differences in population demographics (age, gender and race) and unemployment rates, as well as a proxy for firearm availability and mental health professional shortage area status.

Setting: 9 Arizona counties from 2014 to 2019.

Participants: A policy group was constructed using Pima County (Tucson area) observations. A comparison group was created using data from eight other Arizona counties. 54 county-year observations were analysed.

Intervention: SB 1487, which pre-empted Tucson law and allowed firearms that were seized/surrendered to law enforcement to be recirculated instead of destroyed.

Outcomes and measures: Annual rates of firearm and non-firearm suicides per 100 000 persons extracted from the Centers for Disease Control and Prevention WONDER system.

Results: Over the study period, comparison group counties had an average of 14.87 firearm suicides per 100 000 persons per year, compared with 11.56 firearm suicides per 100 000 persons per year in Pima County. A 1.13 increase in Pima County's firearm suicides per 100 000 persons coincided with the enactment of Arizona's 2016 pre-emption law, relative to comparison group counties over the same period.

Conclusions: SB 1487 was associated with higher firearm suicide rates in Pima County relative to other areas not targeted by the law, assuming fewer firearms were destroyed and more firearms re-entered the greater Tucson area through 2019.

Keywords: health and safety; health policy; public health; suicide.

Figure 1

Firearm suicides per 100 000 persons in Arizona, by county in 2019. Notes: Authors’ analysis of the Centers for Disease Control and Prevention WONDER data. This map describes the firearm suicide rate per 100 000 persons in 2019 for each county included in our analyses. This map also illustrates the relative land size of each Arizona county. Pima County had 14.13 firearm suicides per 100 000 persons in 2019. Counties excluded from our analyses are shown in white.

Figure 2

Unadjusted trends in the firearm suicide rate, by policy group, 2005–2019. Notes: Authors’ analysis of Centers for Disease Control and Prevention WONDER data. This figure shows the unadjusted trends in firearm suicide rates between Pima County (solid black line) and comparison group counties (dashed black line) from 2005 to 2019, allowing for a visual examination of the prepolicy common trends assumption in the primary dependent variable. The postpolicy-enactment period was 2016–2019. Tucson’s ordinance requiring firearms confiscated by (or voluntarily surrendered to) Tucson police to be destroyed was adopted in 2005 and would have been implemented in subsequent years.