State handgun purchase age minimums in the US and adolescent suicide rates: regression discontinuity and difference-in-differences analyses

Examining the Impact of Minimum Handgun Purchase Age and Background Check Legislation on Young Adult Suicide in the United States, 1991-2020

Objectives. To examine the independent and joint effects of state legislation on minimum age for purchasing handguns and background checks on the suicide of young adults aged 18 to 20 years. Methods. We used negative binomial regressions with fixed effects for year and generalized estimating equations for state to estimate the effects of state legislation on annual counts of firearm, nonfirearm, and total young adult suicides in all 50 US states from 1991 to 2020. Results. Minimum age laws decreased the incidence rate of firearm suicide among young adults, an effect that was amplified in states with permit to purchase laws; there was no effect on the nonfirearm or total suicide rate. Permit to purchase laws significantly decreased the young adult firearm suicide incidence rate by 39% (incidence rate ratio [IRR] = 0.61; 95% confidence interval [CI] = 0.51, 0.74) and the overall suicide incidence rate by 14% (IRR = 0.86; 95% CI = 0.75, 0.99), with no effect on the nonfirearm suicide rate. Conclusions. Permit to purchase laws are a more promising avenue for reducing young adult suicides than are age-based restrictions. (Am J Public Health. 2024;114(8):805-813. https://doi.org/10.2105/AJPH.2024.307689).

A Common Ground Gun Violence Prevention Policy Package

In 2022 we conducted a literature review, surveyed 1078 gun owners, and conducted post-survey focus groups and interviews of gun owners and non-gun owners, to determine a common ground gun violence prevention (GVP) policy package. This allowed us to see policies that would save lives and be widely accepted: (1) violent misdemeanor laws, (2) state permit laws, combined with universal background checks; (3) red flag laws. Based on our review of relevant research, we conservatively estimate that in states without any of the policy package components, implementing this package would result in a 27.9% reduction in firearm deaths. We believe that polarization between firearm owners and non-firearm owners, which has thwarted a widely supported response to the problem of gun violence, is largely a harmful myth that can be overcome by including gun owners in the process of fashioning an effective policy approach.

Washington State Assault Weapon Firearm Violence Before and After Firearm Legislation Reform

BACKGROUND

In January of 2019, Washington State (WA) passed Initiative 1639 making it illegal for persons <21 years-old to buy assault weapons (AWs). This study aimed to evaluate the effects of WA-1639 on firearm-related incidents involving AWs by those <21 years-old in WA, hypothesizing a decrease in incidents after WA-1639.

METHODS

Retrospective (2016-2021) data on firearm violence (FV) events were gathered from the Gun Violence Archive. The rate of FV was weighted per 100,000 people. Total monthly incidents, injuries, and deaths were compared pre-law (January 2016-December 2018) vs post-law (January 2019-December 2021) implementation. Mann-Whitney U tests and Poisson's regression were used for analysis.

RESULTS

From 4091 FV incidents (2210 (54.02%) pre-law vs 1881 (45.98%) post-law), 50 involved AWs pre- (2.3%) and 15 (.8%) post-law. Of these, 11 were committed by subjects <21 years-old pre-law and only one occurred post-law. Total incidents of FV (z = -3.80, P < .001), AW incidents (z = -4.28, P < .001), and AW incidents involving someone <21 years-old (z = -3.01, P < .01) decreased post-law. Additionally, regression analysis demonstrated the incident rate ratio (IRR) of all FV (1.23, 95% CI [1.10-1.38], P < .001), all AW FV incidents (3.42, 95% CI [1.70-6.89], P = .001), and AW incidents by subjects <21 years-old (11.53, 95% CI [1.52-87.26], P = .02) were greater pre-law vs post-law.

DISCUSSION

Following implementation of WA-1639, there was a significant decrease in FV incidents and those involving AWs by individuals <21 years-old. This suggests targeted firearm legislation may help curtail FV. Further studies evaluating FV after legislation implementation in other states is needed to confirm these findings.

Association Between the New York SAFE Act and Firearm Suicide and Homicide: An Analysis of Synthetic Controls, New York State, 1999‒2019

Objectives. To assess the association between the New York Secure Ammunition and Firearms Enforcement Act (NY SAFE Act) and firearm suicide and homicide rates. Methods. We employed a synthetic controls approach to investigate the impact of the NY SAFE Act on firearm suicide and firearm homicide rates. We collected state-level data on firearm mortality from the Centers for Disease Control and Prevention's Wide-ranging Online Data for Epidemiologic Research (WONDER) database for the period 1999-2019. We derived statistical inference by using a permutation-based in-place placebo test. Results. The implementation of the NY SAFE Act was associated with a significant reduction in firearm homicide rates, demonstrating a decrease of 63%. This decrease corresponds to an estimated prevention of 1697 deaths between 2013 and 2019. However, there was no association between the NY SAFE Act and firearm suicide rates. Conclusions. As the responsibility for enacting firearm policies increasingly falls on states instead of the federal government, this study provides valuable information that can assist states in making evidence-based decisions regarding the development and implementation of firearm policies that prioritize public safety and aim to prevent firearm-related fatalities. (Am J Public Health. 2023;113(12):1309-1317. https://doi.org/10.2105/AJPH.2023.307400).

Opportunities and challenges in using instrumental variables to study causal effects in nonrandomized stress and trauma research

OBJECTIVE

Researchers are often interested in assessing the causal effect of an exposure on an outcome when randomization is not ethical or feasible. Estimating causal effects by controlling for confounders can be unconvincing because important potential confounders remain unmeasured. Study designs leveraging instrumental variables (IVs) offer alternatives to confounder-control methods but are rarely used in stress and trauma research.

METHOD

We review the conceptual foundations and implementation of IV methods. We discuss strengths and limitations of IV approaches, contrasting with confounder-control methods, and illustrate the relevance of IVs for stress and trauma research.

RESULTS

IV approaches leverage an external or exogenous source of variation in the exposure. Instruments are variables that meet three conditions: relevance (variation in the IV is associated with variation in the chance of exposure), exclusion (the IV only affects the outcome through the exposure), and exchangeability (no unmeasured confounding of the IV-outcome relationship). Interpreting estimates from IV analyses requires an additional assumption, such as monotonicity (the instrument does not change the chance of exposure in different directions for any two individuals). Valid IVs circumvent the need to correctly identify, measure, and control for all confounders of the exposure-outcome relationship. The primary challenge is identifying a valid instrument.

CONCLUSIONS

IV approaches have strengths and weaknesses compared with confounder-control approaches. IVs offers a promising complementary study design to improve evidence about the causal effects of exposures on outcomes relevant to stress and trauma. Collaboration with scientists who are experienced with identifying and analyzing IVs will support this work. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

State Gun Regulations and Reduced Gun Ownership are Associated with Fewer Firearm-Related Suicides Among Both Juveniles and Adults in the USA

BACKGROUND

Few studies have investigated the relationship between specific gun regulations and gun ownership with the firearm-related suicide rate among juveniles and adults across U.S. states. Therefore, this study seeks to determine if gun ownership rates and gun restrictions are related to the firearm-related suicide rate in both the pediatric and adult populations.

METHODS

Fourteen measures of state gun law restrictions and gun ownership were collected. These included Giffords Center ranking, gun ownership percentages, and 12 specific firearm laws. Unadjusted linear regressions modeled the relationship between each individual variable and the rate of firearm-related suicides for adults and children across states. This was repeated using a multivariable linear regression adjusting for poverty, poor mental health, race, gun ownership, and divorce rates by state. P values of <0.004 were considered significant.

RESULTS

In the unadjusted linear regression, 9 of 14 firearm-related measures were statistically associated with fewer firearm-related suicides in adults. Similarly, 9 of 14 measures were found to be associated with fewer firearm-related suicides in the pediatric population. In the multivariable regression, 6 of 14 vs. 5 of 14 measures were statistically associated with fewer firearm-related suicides in the adult and pediatric populations, respectively.

CONCLUSIONS

Ultimately, this study found that increased state gun restrictions and lower gun ownership rates were associated with fewer firearm related suicides among juveniles and adults in the US. This paper provides objective data to help lawmakers as they create gun control legislation that can potentially decrease the rate of fire-arm related suicide.

LEVELS OF EVIDENCE

II.

Comparing Two-way Fixed Effects and New Estimators for Difference-in-Differences: A Simulation Study and Empirical Example

BACKGROUND

Two-way fixed effects methods have been used to estimate effects of policies adopted in different places over time, but they can provide misleading results when effects are heterogeneous or dynamic, and alternate methods have been proposed.

METHODS

We compared methods for estimating the average treatment effect on the treated (ATT) under staggered adoption of policies, including two-way fixed effects, group-time ATT, cohort ATT, and target-trial approaches. We applied each method to assess the impact of Medicaid expansion on preterm birth using the National Center for Health Statistics' birth records. We compared each estimator's performance in a simulation parameterized to mimic the empirical example. We generated constant, heterogeneous, and dynamic effects and calculated bias, mean squared error, and confidence interval coverage of each estimator across 1000 iterations.

RESULTS

Two-way fixed effects estimated that Medicaid expansion increased the risk of preterm birth (risk difference [RD], 0.12; 95% CI = 0.02, 0.22), while the group-time ATT, cohort ATT, and target-trial approaches estimated protective or null effects (group-time RD, -0.16; 95% CI = -0.58, 0.26; cohort RD, -0.02; 95% CI = -0.46, 0.41; target trial RD, -0.16; 95% CI = -0.59, 0.26). In simulations, two-way fixed effects performed well when treatment effects were constant and less well under heterogeneous and dynamic effects.

CONCLUSIONS

We demonstrated why new approaches perform better than two-way fixed effects when treatment effects are heterogeneous or dynamic under a staggered policy adoption design, and created simulation and analysis code to promote understanding and wider use of these methods in the epidemiologic literature.

How have firearm laws changed in states with unexpected decreases or increases in firearm homicide, 1990-2019?

Background

Firearm violence is one of the leading preventable causes of death and injury in the United States and is on the rise. While policies regulating access to firearms offer opportunities to prevent firearm-related deaths, an understanding of the holistic impact of changing state firearm policies on firearm homicide rates over the last 30 years is limited.

Objectives

To identify US states that showed unexpected decreases and increases in firearm homicide rates and summarise their firearm policy changes in the last three decades.

Methods

We analysed changes in firearm homicide rates by US state and county from 1990 to 2019. We triangulated across three estimation approaches to derive state rankings and identify the top and bottom three states which consistently showed unexpected decreases (low outliers) and increases (high outliers) in firearm homicide rates. We summarised firearm policy changes in state outliers using the RAND State Firearm Law Database.

Results

We identified New York, District of Columbia, and Hawaii as low state outliers and Delaware, New Jersey, and Missouri as high state outliers. Low state outliers made more restrictive firearm policy changes than high state outliers, which covered a wider range of policy types. Restrictive changes in high state outliers primarily targeted high-risk populations (e.g., prohibited possessors, safe storage). Specific legislative details, such as the age threshold (18 vs 21 years old) for firearm minimum age requirements, also emerged as important for differentiating low from high state outliers.

Conclusions

While no firearm law change emerged as necessary or sufficient, an accumulation of diverse restrictive firearm policies may be key to alleviating the death toll from firearm homicide.

USA Suicides Compared to Other Western Countries in the 21st Century: Is there a Relationship with Gun Ownership?

OBJECTIVES

Causes of suicide are complex indicating a nation's psycho-socio-economic well-being hence this population-based study explores whether USA suicides worsened compared to nineteen Other Western Countries (OWC) being possibly related to gun ownership in the 21st Century.

METHODS

Total suicide data are drawn from the latest WHO Age-Standardised-Death-Rates per million (pm) controlled for age, sex, and population, along with suicides in the five age- bands 15-34 years to 75 + years. National gun ownership data from the international Small Arms Survey. Chi-square tests any significant difference between American and OWC suicides during the century. Spearman Rank Order correlations are used to determine comparability of suicides and gun ownership per thousand person rates over the period 2000-15.

RESULTS

USA had the highest gun ownership, treble the rate of the next highest country. American Total suicides rose 27%, significantly more than eight other countries (p < 0.05). The USA had significantly worse suicide outcomes for Older (75+) people than three OWC; eleven for Mature Adults 55-74; eight for Adults 34-54 and for ten countries for Young Adults 15-34. Young Adult suicides numbered 12,438, 6,702 gun-related in 2015, exceeding recent USA military losses. Only Young Adult suicides positively correlated with gun ownership (<0.025).

CONCLUSIONS

The key finding is whilst most countries reduced suicides American rates rose substantially this century, raising questions about US society. Importantly the easy access to firearms in the USA makes Young Adult suicide more likely when facing psycho-social stress. This study exposes the vulnerability of distressed young American adults in a permissive gun culture, with its sequel, life-long grieving parents.HighlightsDuring 21st Century USA suicides rose substantially more than other Western nations.Only USA suicides rose >20% amongst Total suicides and in those aged 15-to-74years.USA Young Adult suicides 150,099 in 21st century, 12,438 in 2015, 6,702 were gun-related.

Firearm-Related Injuries and Deaths in Children and Youth

Firearms are the leading cause of death in children and youth 0 to 24 years of age in the United States. In 2020, firearms resulted in 10,197 deaths (fatality rate 9.91/100,000 youth 0-24 years old). Firearms are the leading mechanism of death in pediatric suicides and homicides. Increased access to firearms is associated with increased rates of firearm deaths. Substantial disparities in firearm injuries and deaths exist by age, gender, race, ethnicity, and sexual orientation and gender identity and for deaths related to legal intervention. Barriers to firearm access can decrease the risk to youth for firearm suicide, homicide, or unintentional shooting injury and death. Given the high lethality of firearms and the impulsivity associated with suicidal ideation, removing firearms from the home or securely storing them-referred to as lethal means restriction of firearms-is critical, especially for youth at risk for suicide. Primary care-, emergency department-, mental health-, hospital-, and community-based intervention programs can effectively screen and intervene for individuals at risk for harming themselves or others. The delivery of anticipatory guidance coupled with safety equipment provision improves firearm safer storage. Strong state-level firearm legislation is associated with decreased rates of firearm injuries and death. This includes legislation focused on comprehensive firearm licensing strategies and extreme risk protection order laws. A firm commitment to confront this public health crisis with a multipronged approach engaging all stakeholders, including individuals, families, clinicians, health systems, communities, public health advocates, firearm owners and nonowners, and policy makers, is essential to address the worsening firearm crisis facing US youth today.

State Firearm Laws and Firearm-Related Mortality and Morbidity

This Viewpoint highlights the challenges to passing federal legislation that limits gun ownership and accessibility and summarizes some of the state laws used to successfully lower rates of firearm-related death and injury.

Adolescent Suicide—Understanding Unique Risks and Opportunities for Trauma Centers to Recognize, Intervene, and Prevent a Leading Cause of Death

Purpose of Review

This provides up-to-date epidemiology of adolescent suicide and risk factors for suicide and highlights the overlap of risks for suicide and injury. It reviews signs and symptoms, and the up-to-date evidence on screening for depression, post-traumatic stress disorder (PTSD), suicide, substance abuse, and lethal means, and offers strategies of implementation in trauma centers.

Recent Findings

The incidence of adolescent suicide has continued to rise in the USA to 6.5 per 100,000, with notable racial disparities. The risk factors are complex, but many pre-existing risk factors and sequela after injury such as exposures to violence, suicidal behaviors, substance abuse, depression and post-traumatic stress disorder, and specific injuries including traumatic brain injury and spinal cord injury have further emerged as risks. Studies show rates of suicidality as high as 30% in the acute care setting. There are short screening instruments that can be used to universally screen for depression and suicidality in adolescent trauma patients. Step-up models of care for PTSD are promising to increase screening and services after injury. Lethal means counseling, secure firearm storage practices, and firearm safety policies can reduce the risk of suicide.

Summary

Suicide is the second leading cause of death in US adolescents, and trauma patients have significant risk factors for mental illness and suicidality before and after injury. Trauma centers should strongly consider screening adolescents, establish strategies for mental health support and referrals, and provide lethal means counseling to help prevent suicide.

Age, period, and cohort effects on suicide death in the United States from 1999 to 2018: moderation by sex, race, and firearm involvement

The role of sex, race, and suicide method on recent increases in suicide mortality in the United States remains unclear. Estimating the age, period, and cohort effects underlying suicide mortality trends can provide important insights for the causal hypothesis generating process. We generated updated age-period-cohort effect estimates of recent suicide mortality rates in the US, examining the putative roles of sex, race, and method for suicide, using data from all death certificates in the US between 1999 and 2018. After designating deaths as attributable to suicide according to ICD-10 underlying cause of death codes X60-X84, Y87.0, and U03, we (i) used hexagonal grids to describe rates of suicide by age, period, and cohort visually and (ii) modeled sex-, race-, and suicide method-specific age, period, and cohort effects. We found that, while suicide mortality increased in the US between 1999 and 2018 across age, sex, race, and suicide method, there was substantial heterogeneity in age and cohort effects by method, sex, and race, with a first peak of suicide risk in youth, a second peak in older ages-specific to male firearm suicide, and increased rates among younger cohorts of non-White individuals. Our findings should prompt discussion regarding age-specific clinical firearm safety interventions, drivers of minoritized populations' adverse early-life experiences, and racial differences in access to and quality of mental healthcare.