Incidence of Firearm Suicide in US Congressional Districts Estimated from County-Level Underlying Cause of Death Reports


 Background: Suicide is the most common form of violent death in the US and firearms are the most common means of suicide, contributing to half of all suicide deaths. The focus of this research is calculating suicide and firearm suicide counts and rates for each congressional district in order to highlight the types of legislation and local programs that can address this public health crisis in each district.Methods: Counts of suicides and firearm suicides for the congressional districts were calculated by weighting county counts as reported by the Centers for Disease Control and Prevention for the five-year period 2014 to 2018 by the proportion of the county population allocated to the congressional district for that population group as available from the Census Bureau’s Summary File for the 116th Congress. The weighted counts were then summed over the counties in the congressional district. Results: There are 52 firearm suicides on average per congressional district each year, yet there is tremendous district-level variation across the country and even within states. Seventeen districts—in Massachusetts, New Jersey, New York and Washington, DC—have 10 or fewer firearm suicides each year. On the other hand, 11 districts—in Alaska, Arizona, Colorado, Idaho, Montana, Oklahoma, Oregon, and Tennessee—have over 100 gun suicides each year. 88 percent of the difference in congressional district-level suicide rates is explained by differences in firearm suicide. The proportion of suicides by firearm out of all suicides ranges from 6% to 73% across districts. Rates of suicide by other means were similar across rural and urban districts, while rates of firearm suicide were on average 5 times higher in rural districts (1.77 in urban compared to 10.60 per 100,000 population in rural). Conclusions: Understanding the incidence of firearm suicide in US congressional districts can provide tools for holding elected officials accountable for taking steps-- including research funding, key policies, storage practices, public education initiatives -- to protect the lives of their constituents by preventing firearm suicide.


Background
Suicide is the most common form of violent death in the US and rearms are the most common means of suicide, contributing to half of all suicide deaths.(1) On average over the period 2014 to 2018, there are approximately 23,000 rearm suicide deaths each year in the United States-a rate of 6.7 per 100,000 people.
(1) While these statistics paint a distressing picture, suicide is preventable and reducing rearm suicide in particular could save thousands of lives each year.
As with any public health crisis of this magnitude, the "cure" requires data and science to gure out the causes of the problem and the interventions that work to prevent it. However, a public health approach to preventing suicide is hampered by a lack of up-to-date data with regards to vulnerable groups and meaningful geographic areas.
The objective of this analysis was to estimate suicide and rearm suicide counts and rates for each congressional district of the 435 United States congressional districts as well as the non-voting district of the District of Columbia (DC) using publicly available county-level counts and rates from the Centers for Disease Control and Prevention (CDC). This is essential for pointing to the types of federal and local legislation, policies, and programs that can address this public health crisis in each district. The importance of presenting mortality by congressional district is not unique to rearm deaths. Analysis of congressional district mortality has similarly been calculated for other causes of death, including cancer, coronavirus, opioid use, and multiple causes of mortality. (2)(3)(4)(5) Congressional districts are a valuable geographic unit for data analysis because they all have roughly the same population size, approximately 740,000 residents for the 116th Congress (2019 to 2020).(6) Firearm suicide data for congressional districts can help voters and elected representatives pinpoint the scope and location of the problem, help identify underlying factors present in different places, and mobilize communities to take action to save lives.

Results
There are 52 rearm suicides on average per congressional district each year, yet there is tremendous districtlevel variation across the country and even within states (see Fig. 1 The 20 congressional districts with the lowest rates of rearm suicide are con ned to only three states: Massachusetts, New Jersey, and New York, plus the non-voting District of Columbia (see Table 1). In most of these districts, there were fewer than 10 rearm suicides per year (counts below 10 are suppressed to protect the privacy of individuals in those places). Rates of rearm suicide in these districts are below 2 per 100,000 people. On average, rearm suicides comprise 15 percent of all suicides in these districts, far lower than the national average of 50 percent. The 20 congressional districts with the highest rate of rearm suicide are found across 16 states (see Table   2), all in the Western and Southern US. In stark contrast to the districts with the lowest rates of rearm suicide, these districts have, on average, 106 rearm suicides per year. The rate of rearm suicide in the 20 districts with the highest rates of rearm suicide is more than 10 times higher than that of the 20 districts with the lowest rates of rearm suicide. Rates of rearm suicide in these districts are all above 13 per 100,000 people. Firearm suicides account for 61% of all suicides in these districts.  Among the 43 states with more than one congressional district, ten have differences in average annual incidence of rearm suicide of more than 50 per year (see Table 3). The largest variation in the number of rearm suicides was seen in Arizona between the 4th district (139/year) and the 7th district (50/year). In terms of rate per 100,000 the largest variation within a state was between California's 1st district (11.87/100,000) and the 40th district (1.88/100,000).  Firearm suicide as a proportion of all suicide Nationally, on average from 2014 to 2018, nearly half of suicides involve a rearm, however the range is from a low of 6% to a high of 73%. There are 34 districts across 6 state and the District of Columbia where suicide with a rearm makes up less than 25% of all suicide deaths. This stands in contrast to 21 districts across 7 states where rearm suicides account for 65% or more of all suicide deaths. Focusing only on males, which account for 86% of all rearm suicides, the proportion of rearm suicides out of all suicides ranges from a low of 8% to a high of 77% (with rearm suicide rates of 0.40/100,000 and 13.59/100,000, respectively).
District-level rates con rm that differences in rearm suicide across the US drive differences in suicide: 88% of the difference in congressional district-level suicide rates is explained by differences in rearm suicide (see Fig. 2). While there was a ten-fold difference in rates of rearm suicide for the highest and lowest districts, the 20 districts with the highest suicide rates have an average rate four times higher than the 20 districts with the lowest suicide rates (24.03/100,000 and 5.66/100,000, respectively).

Rural rearm suicide
One clear pattern that emerges from this analysis was the relationship between population density and rearm suicide which exists at the county level was con rmed at the congressional district level (see Fig. 3).

Discussion
This analysis of rearm suicide by congressional district using publicly available county-level mortality reporting here showed that, despite similar population size and equal political representation, there is wide variation in the number and rate of rearm suicides across US congressional districts. On average, the 20 districts with the highest suicide rates have rates four times higher than the lowest 20 districts; the 20 districts with the highest rearm suicide rates have rates ten times higher than the lowest 20 districts. Prior research has shown that suicide rates for all methods, including rearms, differ widely among the 50 states and that those differences are driven by the disparities in rearm suicides. (9) Understanding what is driving the difference in rearm suicide rates -factors such as rearm ownership and laws, race, sex, age, and rurality -can help improve local and federal legislation, polices, and programs towards preventing all suicide. The nding that differences in rearm suicide rates are so key to understanding differences in all suicide is in part because of the lethality of rearms compared to other methods or mechanisms for suicide. Nearly all other methods (such as hanging, poisoning, or drug overdose) are less lethal. For example, 90% of suicide attempts using a gun result in death. By comparison, only 4% of suicide attempts by other means are fatal. (10) There is growing evidence that access to a gun increases the risk of death by suicide. (11,12) There is also growing evidence that laws such as extreme risk protection orders and programs at gun shops, shooting ranges, and law enforcement for temporary storage that provide opportunities to temporarily remove access to rearms when people are at risk can prevent rearm suicide.

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Firearm suicide as a proportion of all suicide is often used in research and evaluation as a proxy for rearm ownership either on its own or alongside surveys or other proxies. (13,14) The range of 6-73% for all persons and for 8-77% for males strongly suggests that rearm ownership varies signi cantly at geographic units below the state level. Further research is needed to understand differences below the state level for rearm ownership and how this may affect or be affected by local policies, programs, and regulations.

Limitations
The estimates are limited according to available data from the CDC and Census as well as simplifying assumptions. Using county-level counts and rates for the populations does assume that differences in suicide rates by counties, possibly because of local support programs, unemployment rates, occupation, or other social factors, matter. Research shows that differences at a state-level matter, for example in access to rearms (whether because of differences in state laws or culture)(9, 12, 15), access to healthcare and mental healthcare services (16), socio-economic differences and access to economic assistance. (17)(18)(19) It also assumes that the difference in congressional district borders by sex and race, where parts of a county were allocated to one or a different congressional district, are more signi cant than differences across congressional borders because of the county-level age structure which were not considered.
Another simplifying assumption made was that 5-year totals and averages could be used despite an increasing trend in rearm suicides over the period. Additionally, the deaths and rates are allocated to current Of the 428 districts analyzed (excluding the known at-large districts), 263 congressional districts included at least one county that was wholly within the geographic boundaries of the district. This means that deaths reported for these counties was wholly included in the congressional district totals, limiting the number of deaths that had to be apportioned partially because of county and congressional district borders overlapping. Conversely, there are counties that wholly include multiple congressional districts. For example, Los Angeles county includes 18 districts, 11 of which are completely within the county borders and 7 that overlap with other counties. Differences across these within-county congressional districts would be unmeasured in this use of county-level rates.
The importance of presenting mortality by congressional district is not unique to rearm violent deaths and the limitations presented here are similar for many other attempts at allocating deaths to this level. (2,4,5) Ideally, the CDC would add congressional district data to its public reporting from the National Vital Statistics System reporting. Short of this, additional validation of these congressional estimates could be done with more detailed datasets that have restricted availability such as the National Violent Death Reporting System.
The fact that 23,000 American lives are claimed each year by a preventable cause is tragic. This analysis helps to provide the data necessary to understand what drives 10-fold differences in the number and rate of rearm suicides across US congressional districts. Increasing understanding of the types of life-saving policies, interventions, and behavioral changes needed to prevent suicide and rearm suicide in particular is essential to a public health approach as well as a tool for holding elected o cials accountable for taking steps to protect the lives of their constituents.

Methods
Data source for counts of rearm suicides and all suicides

Allocation of county deaths to congressional districts
County-level reporting is the most granular geographic unit available publicly. Congressional district borders can be a portion of one county or encompass parts or all of multiple counties. Many US counties straddle two or more districts; many districts include parts of two or more counties. If the distribution of gun suicides was relatively even within a county, one could then simply divide county-level suicides by the proportion of the population of a county that is contained within that district. But neither overall suicide nor rearm suicide are distributed evenly across the population; rather they vary by age, sex, and race.
To account for differences in how county populations are split across districts, Census tract populations for county and congressional district for the 116th Congress borders from the 2010 census counts by sex, race and Hispanic origin were obtained from the Census summary le for the 116th Congress.(6) For the six sex, race, and Hispanic origin groups noted above, two sets of weights were created: the proportion of county population allocated to the congressional district and the proportion of the congressional district population from the county.
Allocation of counts from the county to the congressional district and calculation of rates for the congressional district was based upon the methods from the American Cancer Society (3)   or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.

Figure 2
Association of rearm suicide rate and all suicide rate. Crude rates per 100,000 calculated as an average for the 2014-2018 period. Line of best t, with 95% con dence interval bands. R-squared=0.86, p<0.0001.

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. SupplementalFileCongressionalFirearmSuicide.xlsx