Key Points
Question
What state gun laws, if any, are associated with reduced rates of firearm suicide?
Findings
In this cross-sectional study of 2450 observations collected from 1976 to 2024, the mean overall rate of suicide was 13.7 deaths per 100 000, with 7.9 deaths per 100 000 for firearm-related suicide and 5.8 deaths per 100 000 for non–firearm-related suicide across the study period. Handgun permit requirements, waiting periods, and requiring a license for concealed carry were significantly associated with a reduction in firearm suicide rates.
Meaning
These findings suggest that laws restricting access to guns may be effective in reducing rates of firearm suicide.
This cross-sectional study examines whether state-level firearm laws are associated with firearm-related suicide deaths across all 50 US states over a 49 year period.
Abstract
Importance
While numerous states have enacted laws to reduce access to firearms among high-risk individuals, the evidence regarding the associated outcome of reducing firearm suicide has been mixed, in part due to methodological limitations.
Objective
To examine the association between state firearm laws and firearm-related suicide deaths across all 50 US states during the period from 1976 to 2024.
Design, Setting, and Participants
This cross-sectional study, conducted in December 2025, used a difference-in-differences fixed-effects panel regression with Prais-Winsten correction applied to annual state-level data on firearm-related suicides from all 50 US states from January 1976 through December 2024. Sample data were obtained from the Centers for Disease Control and Prevention–maintained Web-based Injury Statistics Query and Reporting System.
Exposures
Six firearm laws with prior evidence or theoretical plausibility of affecting risk of suicide: (1) required permits to purchase handguns; (2) waiting periods for firearm purchases; (3) laws requiring permits for concealed carry; (4) minimum age requirements; (5) extreme risk protection order laws; and (6) state permit requirements for gun dealers. Laws were modeled with a 2-year lag.
Main Outcomes and Measures
The primary outcome was annual, age-adjusted, state-specific firearm suicide rate, and the negative control outcome was nonfirearm suicide rate. Models accounted for serial autocorrelation and heteroskedasticity in the data and adjusted for a range of sociodemographic covariates.
Results
Across the study period, 2450 observations were collected. The mean overall suicide rate was 13.7 deaths per 100 000 with 7.9 deaths per 100 000 for firearm-related suicide and 5.8 deaths per 100 000 for non–firearm-related suicide. Firearm suicide rates varied 8-fold across states in 2024 (1.8 deaths per 100 000 in New York vs 15.1 deaths per 100 000 in Wyoming). Handgun permit laws (−6.7%; 95% CI, −9.7% to −3.7%), waiting periods (−12.5%; 95% CI, −22.1% to −1.7%), and requirements for a license for concealed carry (−8.9%; 95% CI, −13.1% to −4.8%) were significantly associated with decreases in firearm suicide rates but not with nonfirearm suicide rates. States with 1 (−8.1%; 95% CI, −11.4% to −4.7%), 2 (−12.5%; 95% CI, −16.3% to −8.5%), or all 3 (−25.3%; 95% CI, −34.2% to −15.2%) of these laws (handgun permit requirements, waiting periods, and concealed carry permits) had progressively lower firearm suicide rates.
Conclusions and Relevance
In this cross-sectional study analyzing data from 49 years and 50 states, permit-to-purchase requirements for handguns, waiting periods, and the requirement for a license for concealed carry were each independently and cumulatively associated with significantly lower firearm suicide rates.
Introduction
Suicide by firearm remains a critical public health issue in the US, accounting for more than one-half of all deaths by suicide annually.1 In response, many states have enacted firearm legislation aimed at reducing access to firearms among high-risk individuals, including permit-to-purchase and universal background check laws. However, the empirical evidence on the associated outcome of these laws in reducing firearm suicide remains mixed,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22 in part due to limitations in study design and analytic methodology.
Previous studies2,3,4,5 used cross-sectional designs or difference-in-differences (DiD) models without adequately accounting for serial correlation in suicide rates over time. This omission can result in inefficient estimates and biased SEs, potentially leading to incorrect inferences about policy associations. Recognizing this concern, recent reviews have explicitly recommended the use of regression methods that adjust for serial autocorrelation, such as Prais-Winsten estimation, in the evaluation of state-level policy interventions.6 Despite these recommendations, few studies evaluating firearm laws and suicide outcomes have adopted such methods. This is important because in these panel data, suicide rates in a state in a given year would be expected to be correlated with rates in that state in other years. Model misspecification due to omitted variables is also likely and could cause serial autocorrelation.
In this study, we address these methodological shortcomings by using a DiD fixed-effects panel model combined with Prais-Winsten regression to account for first-order serial correlation and heteroskedasticity in a 49-year panel of state-level data. We examine the association between state-level laws and firearm suicide rates, with controls for time-varying state characteristics and fixed effects for both year and state. By adopting best-practice econometric techniques, our study strengthens the empirical basis for understanding how firearm laws may influence suicide risk and provides more reliable evidence to inform firearm policy.
Methods
Study Design
This cross-sectional study used a DiD panel model with annual state-level data to examine the association between state firearm laws and firearm-related suicide deaths among all 50 states during the period from 1976 to 2024. The analysis consisted of a linear regression with fixed effects for year and state, indicator variables for the presence or absence of a particular law in a given state, and a vector of time-varying state-level factors. We used an approach that directly models serial autocorrelation in the data and accounts for heteroskedasticity, or unequal variances in error terms, primarily due to the widely varying population sizes across states. The DiD design is well-suited to examine whether changes in state firearm laws are associated with subsequent changes in firearm death rates in a given state that are significantly different from changes in those rates in other states that did not implement those laws. We examined 3 outcome variables: annual age-adjusted rates of firearm-related, non–firearm-related, and total suicide. The study adhered to the standards for reporting cross-sectional studies that are outlined by the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines. Because it involved secondary analysis of deidentified, publicly available datasets, the study was approved by the Tufts University institutional review board as non-human participant research and the need for informed consent was waived.
Sample
The sample consisted of all 50 US states during the 49-year period from 1976 to 2024. Each observation consisted of a year-state combination, the age-adjusted suicide rate, the status of the state’s firearm laws, and a set of state-level control variables for that year and state.
Data and Measures
Outcome Variables
The primary outcome variables were the logged annual, age-adjusted, state-specific rates of firearm-related, non–firearm-related, and total suicides, which were obtained from the Centers for Disease Control and Prevention (CDC)–maintained Web-based Injury Statistics Query and Reporting System (CDC WISQARS) .23 This archive compiles cause-specific mortality data from the National Center for Health Statistics, derived from death certificates as part of the CDC’s National Vital Statistics System.23,24 We obtained data for the years 1981 to 2024 by downloading them from the CDC WISQARS website. An archived database was used for the period from 1976 to 1980.25
Primary Estimator Variables
We used dichotomous indicator variables (0 or 1) to represent the presence or absence of a particular firearm law in a given year and state. State firearm laws were obtained from the Tufts Clinical and Translational Science Institute State Firearm Law Database,26 which provides the status of 72 different gun policy provisions in each state from 1976 to the present. This database was created through examination of the legislative history and text of state statutes and session laws using Westlaw Edge.27 Laws are characterized by the year they went into effect, not by the specific date.
We selected for analysis state firearm laws in our database for which there was supportive or moderate evidence of an association on firearm suicide in the RAND critical review of research evidence of US gun policies28 or in a recent study that used a machine learning approach to identify policies that best estimate state-level firearm suicide rates.29 These included: (1) state handgun permit requirements; (2) waiting periods (a minimum of 3 days or more); (3) laws requiring a license for concealed carry (the opposite of permitless carry); (4) age requirements (ie, age 21 years for purchase of handguns); (5) extreme risk protection orders; and (6) laws requiring gun dealers to have a license. Child access prevention laws were not included because this study examines overall suicide rates (all ages), so we would not expect to be able to detect an associated outcome of child access prevention laws on the entire population.
Most of the laws we examined require systematic, institutional procedural changes and, therefore, would not be expected to have an immediate impact on suicide rates. For example, permitting systems may take several years to establish, and extreme risk protection order laws take planning and training before they can be implemented. For this reason, firearm laws were lagged by 2 years so that they were considered as being in place in the first full year after they had been in effect for 2 years. We conducted a sensitivity analysis to check whether the results were robust to the number of years chosen as the lag. Models were run with lags ranging from 0 to 6 years and compared with the results for a 2-year lag.
Control Variables
In order to address potential confounding variables, we controlled for factors that have been found in previous research to be associated with suicide rates and that could also plausibly be related to the likelihood of enactment of state firearm laws. The time-varying state factors chosen for inclusion in the models were (1) per capita alcohol consumption7,30; (2) poverty7,31; (3) unemployment7,31,32; (4) nonhomicide violent crime rate (aggravated assault, robbery, and forcible rape)7,32; (5) property crime rate (burglary, larceny theft, and motor vehicle theft)32; (6) percentage non-Hispanic Black population33; (7) percentage young population (ages 15-29 years)33; (8) percentage of male individuals among population ages 15 to 29 yeras7,33,34,35; (9) education level (percentage of population with a Bachelor’s degree or higher)36,37; and (10) household gun ownership, as measured by a validated proxy based on the percentage of firearm-related suicide deaths and the hunting license rate.38 Nationally collected survey data on state-level household gun ownership have only been collected sporadically over time, the last being in 2004.
We obtained data on per capita alcohol consumption from the National Institute on Alcohol Abuse and Alcoholism for the years up until 2023.39 Alcohol consumption by state for 2023 was obtained from the WiseVoter state rankings.40 Since alcohol consumption data are not yet available for 2024, we assigned the 2023 values to 2024. Demographic variables, poverty, education, and unemployment were obtained from the annual American Community Survey 1-year estimates.41 Data on race and ethnicity reported in the American Community Survey are self-reported. First, ethnicity is categorized as Hispanic or non-Hispanic, and then race is categorized. The percentage Black population in this study refers to persons classified as non-Hispanic Black. For the years 1976 to 1980, population and demographic data were obtained from the Bureau of the Census State Intercensal Tables.42,43 Poverty rates for the years 1976 to 1979 were linearly interpolated from the data for 1975 and 1980 because they were not available for these years. We used the 1980 Statistical Abstract of the US to obtain unemployment rates for the years 1976 to 1979. We used the Statistical Abstracts of the US for the years 197944 and 1982 to 198345 to obtain educational attainment for 1976 and 1980 and then interpolated the values for 1977 to 1979. For the years 1976 to 1979, we interpolated the percentage non-Hispanic Black population in each state from 1975 and 1980 data. We obtained violent and property crime rates from the Uniform Crime Reports46 and the FBI Crime Data Explorer.47 Finally, since the 2024 data were not yet available for unemployment, poverty, education, violent crime, and property crime, we assigned the 2023 values to 2024 for these variables.
Statistical Analysis
Because the treatment (ie, implementation of laws) differs in time across treated units (ie, states), we employed a 2-way fixed effects DiD linear regression model that included fixed effects for year and state and an indicator variable for the presence or absence of a particular law in that year and that state. The formal model was calculated as ln(fsst) = α + β1 (Ls[t − 2]) + β2 (Cst) + yt + zs + est, where ln(fsst) is the natural log of the firearm suicide rate in state s at time t, Ls[t − 2] was a dummy variable for the presence or absence of a particular law in state s at time t − 2, Cst was a vector of control variables (specified previously), yt were year fixed effects, zs were state fixed effects, and est was the error term. This model compared changes in suicide rates from before to after the implementation of a law in an intervention state with contemporaneous changes in suicide rates in control states (ie, states without the law). It has been shown that the 2-way fixed-effects DiD estimator shown previously represents a weighted average of all possible 2 by 2 DiD estimators that compare states with and without laws to each other over time and that compare before and after observations in a single state over time.48
One assumption of the model was that there was no correlation between error terms from one year to the next (serial autocorrelation).49 This assumption was violated based on a Durbin-Watson statistic of 1.1, which was far from the expected value of 2 if there was no serial autocorrelation.50 Another assumption of the model was that the variances of the error terms were equal across states and years (ie, homoskedastic). Because of the sizable differences in population sizes across states, this assumption was also violated, which introduced heteroskedasticity.49 The presence of serial autocorrelation or heteroskedasticity would have resulted in inefficient estimates of regression coefficients and biased estimation of their SEs.49 To address this problem, we used Prais-Winsten regression, a generalized least squares estimator for a linear regression in which the errors are serially correlated and heteroskedastic.49,50 The Prais-Winsten regression transformed the error terms into serially uncorrelated errors.49 We implemented this in Stata statistical software version 17 (StataCorp) using the prais command.50 In addition, we used robust SEs, which are unbiased even in the presence of serial autocorrelation or heteroskedasticity.50 The full Stata syntax is shown in eMethods in Supplement 1. Several econometric analyses of panel data with serial autocorrelation have used this approach.51,52,53,54,55 After the Prais-Winsten transformation, the final model showed a Durbin-Watson statistic of 2.1, close enough to 2 to conclude that the errors are not serially correlated.50
As the outcome variable was log-transformed, we exponentiated the regression coefficients in order to interpret them as the percentage change in the outcome associated with the implementation of the law. The control variables were standardized so that the exponentiated regression coefficients could be interpreted as the percentage change in the suicide rate associated with each 1-SD increase in the value of the control variable.
With regard to falsification tests, Swanson et al have recommended that studies of what works to reduce gun violence should employ falsification tests in which a model is analyzed that would conceptually be expected to yield null results.56 The failure to find a null result then calls into question the validity of any positive results. As a falsification test, we used a negative control outcome, examining the relationship between the implementation of each type of law and the non-firearm suicide rate. If these laws were found to be associated with both lower firearm and non-firearm suicide rates, it would call into question the validity of the observed association between the laws and firearm suicide rates. Notably, the correlation between firearm and non-firearm suicide rates was only 0.15.
Results
Across the study period from 1976 to 2024, 2450 samples were collected from all 50 US states, indicating the mean total suicide rate was 13.7 deaths per 100 000: 7.9 deaths per 100 000 for firearm-related suicide and 5.8 deaths per 100 000 for non–firearm-related suicide. Firearm suicide rates varied 8-fold across states in 2024 (1.8 deaths per 100 000 in New York vs 15.1 deaths per 100 000 in Wyoming) (Table 1). Nationally, firearm suicide rates remained stable from 1976 to 1990, declined during the 1990s, but then increased markedly from 2006 to 2023 before dropping in 2024 (Figure 1).
Table 1. Status of Firearm Suicide Rates and State Firearm Laws in 2024.
| State | Age-adjusted suicide by firearm rate, 2024, deaths/100 000 | Firearm law | Total No. of firearm laws (of these 6), 2024 | |||||
|---|---|---|---|---|---|---|---|---|
| Permit required for all handgun purchases | Waiting period for all firearm sales | Permit required for concealed carry (no permitless carry)a | Age 21 y for handgun purchase | Extreme risk protection order (red flag) law | Dealer license required for all firearm sales | |||
| Wyoming | 15.1 | No | No | No (2011) | Yes (2010) | No | No | 1 |
| Alaska | 14.6 | No | No | No (2003) | No | No | No | 0 |
| Montana | 13.8 | No | No | No (2021) | No | No | No | 0 |
| New Mexico | 11.5 | No | Yes (2024) | Yes | No | Yes (2020) | No | 3 |
| Idaho | 11.1 | No | No | No (2016) | No | No | No | 0 |
| Oklahoma | 10.3 | No | No | No (2019) | No | No | No | 0 |
| Arkansas | 10.0 | No | No | No (2021) | No | No | No | 0 |
| South Dakota | 9.8 | No | No | No (2019) | No | No | No | 0 |
| Nevada | 9.5 | No | No | Yes | No | Yes (2020) | No | 2 |
| Kentucky | 9.3 | No | No | No (2019) | No | No | No | 0 |
| Alabama | 9.0 | No | No | No (2023) | No | No | No | 0 |
| Arizona | 9.0 | No | No | No (2010) | No | No | No | 0 |
| Colorado | 8.9 | No | Yes (2023) | Yes | Yes (2023) | Yes (2019) | No | 4 |
| Utah | 8.9 | No | No | No (2021) | No | No | No | 0 |
| Missouri | 8.4 | No (repealed 2007) | No | No (2017) | No | No | No | 0 |
| West Virginia | 8.4 | No | No | No (2016) | Yes (2010) | No | No | 1 |
| Indiana | 8.3 | No | No | No (2022) | No | Yes (2006) | No | 1 |
| Maine | 8.3 | No | Yes (2024) | No (2015) | No | No | No | 1 |
| Oregon | 8.3 | No | No | Yes | No | Yes (2018) | No | 2 |
| Kansas | 8.1 | No | No | No (2015) | No | No | No | 0 |
| South Carolina | 8.1 | No | No | No (2024) | No | No | No | 0 |
| Tennessee | 8.0 | No | No | No (2021) | No | No | No | 0 |
| Iowa | 7.8 | No (repealed 2021) | No | No (2021) | Yes (1979) | No | No | 1 |
| Mississippi | 7.8 | No | No | No (2015) | No | No | No | 0 |
| North Dakota | 7.6 | No | No | No (2017) | No | No | No | 0 |
| Georgia | 7.5 | No | No | No (2022) | No | No | No | 0 |
| Louisiana | 7.5 | No | No | No (2024) | No | No | No | 0 |
| North Carolina | 7.1 | No (repealed 2023) | No | Yes | No | No | No | 1 |
| Texas | 7.0 | No | No | No (2021) | No | No | No | 0 |
| Ohio | 6.8 | No | No | No (2022) | Yes (prior to 1976) | No | No | 1 |
| Nebraska | 6.6 | No | No | No (2023) | Yes (1991) | No | No | 1 |
| New Hampshire | 6.6 | No | No | No (2017) | No | No | No | 0 |
| Florida | 6.5 | No | Yes (2018) | No (2023) | Yes (2018) | Yes (2018) | No | 3 |
| Vermont | 6.2 | No | Yes (2023) | No (prior to 1976) | Yes (2018) | Yes (2018) | No | 3 |
| Wisconsin | 6.2 | No | No | Yes | No | No | No | 1 |
| Virginia | 6.1 | No (repealed 2004) | No | Yes | No | Yes (2020) | No | 2 |
| Washington | 5.9 | No | Yes (2024) | Yes | Yes (2019) | Yes (2016) | Yes (1994) | 5 |
| Michigan | 5.7 | Yes (2024) repealed (2012) |
No | Yes | No | Yes (2024) | No | 3 |
| Pennsylvania | 5.6 | No | No | Yes | No | No | Yes (1995) | 2 |
| Minnesota | 5.2 | No | No | Yes | No | Yes (2024) | No | 2 |
| Delaware | 4.4 | Yes (2024) | No | Yes | Yes (1987) | Yes (2018) | No | 4 |
| Illinois | 3.8 | Yes (prior to 1976) | Yes (prior to 1976) | Yes | No | Yes (2019) | Yes (2019) | 5 |
| Maryland | 3.5 | No | No | Yes | Yes (1996) | Yes (2018) | No | 3 |
| California | 2.8 | Yes (1994) | Yes (1990) | Yes | Yes (1985) | Yes (2016) | Yes (1990) | 6 |
| Rhode Island | 2.8 | Yes (prior to 1976) | Yes (1990) | Yes | Yes (prior to 1976) | Yes (2018) | Yes (prior to 1976) | 6 |
| Connecticut | 2.7 | Yes (1995) | No | Yes | Yes (1994) | Yes (1999) | No | 4 |
| Massachusetts | 1.9 | Yes (prior to 1976) | No | Yes | Yes (1998) | Yes (2018) | Yes (prior to 1976) | 5 |
| New York | 1.8 | Yes (prior to 1976) | No | Yes | Yes (2000) | Yes (2019) | No | 3 |
| New Jersey | 1.6 | Yes (prior to 1976) | No | Yes | Yes (2001) | Yes (2019) | Yes (prior to 1976) | 5 |
| Hawaii | 1.4 | Yes (prior to 1976) | Yes (1981) | Yes | Yes (1994) | Yes (2020) | Yes (prior to 1976) | 6 |
Year in which concealed carry permit law was repealed and state became permitless carry.
Figure 1. Line Graph of Trends in National Suicide Rates, 1976-2024.
When examined individually, all 6 of the laws were significantly associated with lower firearm suicide rates; however, only 3 of these laws passed the falsification test (meaning that they were significantly associated with firearm suicide rates but not nonfirearm suicide rates): permits required for handguns, waiting period required for all firearm purchases, and concealed carry license requirements (Table 2). Handgun permit laws were associated with 6.7% (95% CI, −9.7% to −3.7%) lower firearm suicide rates, waiting period laws with 12.5% (95% CI, −22.1% to −1.7%) lower firearm suicide rates, and concealed carry license laws with 8.9% (95% CI, −13.1% to −4.8%) lower firearm suicide rates.
Table 2. Regression Results: Percentage Change in Firearm and Nonfirearm Suicide Rates Associated With Firearm Laws.
| Firearm law | Age-adjusted suicide rate, % change (95% CI)a | |
|---|---|---|
| Firearm | Nonfirearm | |
| Permits required for handgun purchases | −6.7 (−9.7 to −3.7) | −2.6 (−5.5 to +0.4) |
| Waiting period for all firearm purchases | −12.5 (−22.1 to −1.7) | −5.6 (−12.5 to +1.8) |
| Concealed carry license required | −8.9 (−13.1 to −4.8) | −2.5 (−7.0 to +1.8) |
| Age 21 y for purchase of firearms | −7.1 (−9.8 to −4.4) | −5.0 (−7.6 to −2.4) |
| Extreme risk protection order (red flag) law | −7.2 (−10.6 to −3.7) | −5.3 (−8.1 to −2.3) |
| Dealer license required for sale of all firearms | −4.1 (−8.0 to −0.1) | −9.8 (−13.3 to −6.2) |
Percentage change in outcome variable associated with the firearm law.
To examine the possible joint associations of multiple laws and to further test the validity of these findings, we summed the number of these 3 laws (handgun permits, waiting periods, and concealed carry license requirements) (see Figure 2 for the 2024 status of these laws) to explore whether the presence of multiple laws was associated with steadily decreasing firearm suicide rates (Table 3). There was a monotonic decrease in firearm suicide rates: the presence of 1 of these laws was associated with 8.1% (95% CI, −11.4% to −4.7%) lower firearm suicide rates, the presence of 2 of these laws with 12.5% (95% CI, −16.3% to −8.5%) lower firearm suicide rates, and the presence of all 3 of these laws with 25.3% (95% CI, −34.2% to −15.2%) lower firearm suicide rates.
Figure 2. Map of Combined Number of Handgun Permit Laws, Waiting Period Laws, and Concealed Carry Permit Laws by State, 2024.
Table 3. Final Regression Model Results: Percentage Change in Suicide Rates Associated With Combination of 3 Specific Firearm Laws.
| Characteristics | Age-adjusted suicide rate, % change (95% CI)a | ||
|---|---|---|---|
| Total | Firearm | Nonfirearm | |
| Control variables | |||
| Percentage population young | 0.0 (−2.9 to 3.0) | +0.2 (−4.0 to 4.6) | −1.5 (−6.9 to 4.2) |
| Population male | 3.0 (1.2 to 4.8) | 4.4 (1.9 to 7.0) | 2.5 (−0.3 to 5.3) |
| Percentage population non-Hispanic Black | −17.1 (−22.6 to −11.2) | −19.6 (−26.1 to −12.4) | −15.6 (−22.9 to −7.7) |
| Violent crime rate | 4.8 (3.2 to 6.5) | 6.0 (3.9 to 8.0) | 3.0% (0.5 to 5.5) |
| Property crime rate | 5.1 (3.1 to 7.1) | 4.4 (1.8 to 7.0) | 11.0 (8.1 to 14.0) |
| Per capita alcohol | 3.1 (0.8 to 5.4) | 2.8 (0.1 to 5.6) | 2.6 (−0.5 to 5.9) |
| Poverty rate | 0.6 (−0.4 to 1.6) | 0.8 (−0.4 to 2.0) | −0.6 (−1.9 to 0.7) |
| Unemployment rate | 0.5 (−0.6 to 1.6) | −0.4 (−1.7 to 0.9) | 0.6 (−1.0 to 2.2) |
| Education | −3.3 (−5.6 to −0.9) | −4.6 (−7.5 to −1.6) | −0.6 (−9.0 to −2.8) |
| Gun ownership proxy | −0.6 (−3.0 to 1.7) | 31.8 (21.3 to 43.2) | −31.7 (−36.7 to −26.4) |
| No. of state firearm laws of 3b | |||
| No laws | 0 [Reference] | 0 [Reference] | 0 [Reference] |
| 1 law | −5.2 (−8.1 to −2.1) | −8.1 (−11.4 to −4.7) | −2.4 (−6.5 to 1.9) |
| 2 laws | −7.1 (−10.6 to −3.6) | −12.5 (−16.3 to −8.5) | −3.9 (−8.4 to 0.8) |
| 3 laws | −15.8 (−22.6 to −8.4) | −25.3 (−34.2 to −15.2) | −11.1 (−19.5 to −1.8) |
| Specific combinations of laws | |||
| No laws | 0 [Reference] | 0 [Reference] | 0 [Reference] |
| Concealed carry permit only | −4.7 (−7.6 to −1.7) | −7.4 (−10.6 to −4.0) | −2.1 (−6.1 to 2.1) |
| Permits required for handgun purchase and concealed carry | −6.5 (−10.0 to −2.8) | −11.8 (−15.9 to −7.5) | −3.7 (−8.3to 1.0) |
| All 3 laws | −14.6 (−21.4 to −7.1) | −23.6 (−32.8 to −13.2) | −10.3 (−18.5 to −1.2) |
Percentage change in outcome variable associated with the number of firearm laws or with each 1 SD increase in the variable.
Laws include (1) permits required for purchase of all firearms; (2) waiting periods for all firearm purchases; and (3) concealed carry permit required (ie, not a permitless carry state).
Simply examining the number of these laws does not identify how specific combinations of laws are associated with firearm suicide rates. We therefore tested all possible combinations of the 3 laws, except where there were fewer than 15 observations in which case the law combination was not included in the analysis (eTable 1 in Supplement 1). Having a concealed carry permit law alone was associated with −7.4% (95% CI, −10.6% to −4.0%) lower firearm suicide rates, requiring permits for concealed carry and for handgun purchase with −11.8% (95% CI, −15.9% to −7.5%) lower firearm suicide rates, and the presence of all 3 of these laws with −23.6% (95% CI, −32.8% to −13.2%) lower firearm suicide rates (Table 3).
For the permit, waiting period, and concealed carry license laws, we conducted a sensitivity analysis in which we lagged the laws by 0 to 6 years (eTable 2 in Supplement 1). The results were not sensitive to the lag period used.
Discussion
In this cross-sectional analysis of 49 years of state-level data, we found that 3 firearm laws (permit requirements for handgun purchase), mandatory waiting periods, and the requirement for a concealed carry license) were each independently associated with significantly lower firearm suicide rates. When all three were in place, states experienced a 25.3% lower firearm suicide rate compared with states without any of these laws. These associations remained after adjusting for a broad range of demographic, economic, and criminological factors and after accounting for serial correlation and heteroskedasticity in the data.
These findings align with the hypothesis that firearm access plays a critical role in suicide risk. Permit-to-purchase, waiting period, and concealed carry permitting laws may inhibit firearm availability to persons at risk of self-harm. Importantly, these associations were specific to firearm suicide and not observed for nonfirearm suicides, strengthening the inference that these laws influence method-specific rather than general suicide risk.
We also found that the association between these laws and suicide outcomes was dose-responsive: states that enacted more of the 3 key laws experienced progressively greater reductions in firearm suicide rates. This cumulative association supports the idea that a combination of laws may be more protective than any single law alone. Our results, therefore, suggest that comprehensive firearm policy frameworks, rather than isolated statutes, may offer the greatest public health benefit.
We did find significant associations between age restrictions, extreme risk protection order laws, and dealer licensing laws and lower rates of firearm suicide; however, each of these laws was also associated with nonfirearm suicide. This makes a causal interpretation of these findings less plausible and suggests that unmeasured state-level factors rather than firearm-specific outcomes may explain these observed associations. Future studies might explore the potential role of state differences in mental health treatment access and health insurance coverage.
Limitations
This study had some limitations. As this is a cross-sectional study, we cannot draw causal conclusions. In addition, just prior to the implementation of state handgun permit and waiting period laws, firearm suicide rates were substantially lower in implementing states (eTables 3, 4 and 5 in Supplement 1). However, in the 5 years prior to the implementation of all 3 types of laws, there was no clear pattern in the rate of change in firearm suicide rates in implementing compared with nonimplementing states. Because of this limitation, these findings need to be confirmed in subsequent studies, especially those using alternative methodologies, such as synthetic controls. Another important limitation is that states tend to enact laws together; thus, it is difficult to isolate the impact of 1 particular law. Finally, we were unable to examine suicide attempts as an outcome because of the lack of state-level historical data, though case-fatality rates for firearm suicide are approximately 90%.57,58
Conclusions
Our results suggest that a combination of state laws requiring permits for the purchase, possession, and concealed carry of handguns and waiting periods before firearm sales is associated with significantly lower rates of firearm-related suicide. To reduce firearm suicide rates, states should consider adopting a package of policies that restrict easy access to firearms among people who may pose a danger to themselves.
eMethods. Syntax Used to Run the Main Analysis
eTable 1. Number of Observations for Specific Combinations of Handgun Permit Laws, Waiting Period Laws, and Concealed Carry Permit Laws and Average Firearm Suicide Rate for Each Combination
eTable 2. Sensitivity Analysis—Regression Results for Laws Assuming Different Lag Periods: Percentage Change in Firearm Suicide Rate Associated with Laws
eTable 3. Trends in Firearm Suicide Rates Prior to Implementation of State Gun Permitting Laws: Implementing States Compared to All Other States Without Permitting Laws Combined
eTable 4. Trends in Firearm Suicide Rates Prior to Implementation of State Waiting Period Laws: Implementing States Compared to All Other States Without Waiting Period Laws Combined
eTable 5. Trends in Firearm Suicide Rates Prior to Implementation of State Permitless Carry Laws: Implementing States Compared to All Other States Without Permitless Laws Combined
Data Sharing Statement
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eMethods. Syntax Used to Run the Main Analysis
eTable 1. Number of Observations for Specific Combinations of Handgun Permit Laws, Waiting Period Laws, and Concealed Carry Permit Laws and Average Firearm Suicide Rate for Each Combination
eTable 2. Sensitivity Analysis—Regression Results for Laws Assuming Different Lag Periods: Percentage Change in Firearm Suicide Rate Associated with Laws
eTable 3. Trends in Firearm Suicide Rates Prior to Implementation of State Gun Permitting Laws: Implementing States Compared to All Other States Without Permitting Laws Combined
eTable 4. Trends in Firearm Suicide Rates Prior to Implementation of State Waiting Period Laws: Implementing States Compared to All Other States Without Waiting Period Laws Combined
eTable 5. Trends in Firearm Suicide Rates Prior to Implementation of State Permitless Carry Laws: Implementing States Compared to All Other States Without Permitless Laws Combined
Data Sharing Statement
