Injury Prevention
Homicide and suicide risks associated with firearms in the home: A national case-control study,☆☆,

https://doi.org/10.1067/mem.2003.187Get rights and content

Abstract

Study objective: I test the hypothesis that having a gun in the home is a risk factor for adults to be killed (homicide) or to commit suicide. Methods: Two case-control analyses were based on national samples of subjects 18 years of age or older. Homicide and suicide case subjects were drawn from the 1993 National Mortality Followback Survey. Living control subjects were drawn from the 1994 National Health Interview Survey. Ten control subjects matched by sex, race, and age group were sought for each case subject. Results: The homicide sample consisted of 1,720 case subjects and 8,084 control subjects. Compared with adults in homes with no guns, the adjusted odds ratio (OR) for homicide was 1.41 (95% confidence interval [CI] 1.20 to 1.65) for adults with a gun at home and was particularly high among women (adjusted OR 2.72; 95% CI 1.89 to 3.90) compared with men (adjusted OR 1.23; 95% CI 1.01 to 1.49) and among nonwhite subjects (adjusted OR 1.74; 95% CI 1.37 to 2.21) compared with white subjects (adjusted OR 1.27; 95% CI 1.03 to 1.56). Further analyses revealed that a gun in the home was a risk factor for homicide by firearm means (adjusted OR 1.72; 95% CI 1.40 to 2.12) but not by nonfirearm means (OR 0.83; 95% CI 0.62 to 1.11). The suicide sample consisted of 1,959 case subjects and 13,535 control subjects. The adjusted OR for suicide was 3.44 (95% CI 3.06 to 3.86) for persons with a gun at home. However, further analysis revealed that having a firearm in the home was a risk factor for suicide by firearm (adjusted OR 16.89; 95% CI 13.26 to 21.52) but was inversely associated with suicide by other means (adjusted OR 0.68; 95% CI 0.55 to 0.84). Conclusion: Having a gun at home is a risk factor for adults to be shot fatally (gun homicide) or commit suicide with a firearm. Physicians should continue to discuss with patients the implications of keeping guns at home. Additional studies are warranted to address study limitations and to better understand the implications of firearm ownership. [Ann Emerg Med. 2003;41:771-782.]

Introduction

Emergency department staff bear witness daily to the devastation caused by guns—more than 160 patients are treated for gunshot trauma in the United States each day1—and the American College of Emergency Physicians (ACEP) champions the potential to improve public health throughout the nation by focusing on firearms in particular.2 If the potential is proportional to the exposure, it is great indeed: 1 in 3 US households contains firearms, and the number of guns in those homes approaches fully 200 million.3

By contrast, the number of case-control studies on gun-related mortality is commensurate with neither the death toll nor the firearms stock. Case-control designs have been used only twice to test whether access to guns makes Americans more likely to be shot and killed (homicide),4, 5 only once to test the converse (ie, whether owning a gun makes one more likely to kill another person),6 only once to examine the likelihood of being shot and killed unintentionally,7 and only 6 times to test whether access to guns poses a suicide risk.5, 8, 9, 10, 11, 12 Yet epidemiologists rely on the case-control design to make causal inferences,13 especially for exposures not studied through randomized trials (guns are not assigned to some persons and kept from others). It is noteworthy that emergency physicians must rely on so little empiric evidence to explain the cause of a disease they treat daily.

Why are there so few attempts to quantify how gun availability and gun death relate? Perhaps we interpret the United States' experience as evidence enough that keeping guns at home increases the likelihood of being shot. Many homes contain guns,3 almost half (43%) of all homicides and suicides occur in a home,14 and most victims are shot (56% of the homicides and 61% of the suicides in 1998).14 Furthermore, should we try to make the case that this association is causal, we can point to the few case-control studies that do exist,4, 5, 7, 8 bolster our position with evidence that areas with high gun ownership rates have the highest rates of gun-related mortality,15, 16, 17, 18, 19, 20, 21 and make an argument that seems to satisfice.

On the other hand is the reality that most Americans who buy a handgun think it will protect their homes and families.3 This practice is defended by citing evidence that persons frequently and effectively use guns to keep from being attacked and killed.22

The studies behind both conclusions have limitations: that guns confer protection22 because the statistical method could have overestimated their benefit,23, 24 and that persons with guns in their home are at risk to be killed4, 5, 7, 8 because the results might be biased.25 Whether gun ownership has a net benefit or risk remains debatable.26, 27, 28, 29

An overlooked characteristic is that only one of the homicide and one of the suicide case-control studies (ie, those by Kellermann et al4, 8) studied adults and classified individuals with the most direct measure of exposure used to date: whether their households contained guns. Despite this strength, both studies could have inaccurately estimated the effect of gun ownership because important confounding factors were not accounted for. Because of study limitations and suggesting that the deleterious effects of gun ownership are truly so large, these articles have, in the 10 years since their publication, inspired a paper trail of challenges that continues to grow.25, 30, 31, 32, 33, 34, 35, 36 We typically demand multiple tests of a hypothesis before judging the efficacy of a protective or risk factor.37 No such literature has followed.

This study used case-control methods, national samples of adult homicide and suicide victims, and living matched control subjects and tested the hypothesis that having a gun in the home is a risk factor to be killed (homicide) or commit suicide.

Section snippets

Materials and methods

The case subjects and control subjects came from different data sources. Case subjects were drawn from the National Mortality Followback Survey (NMFS). The National Center for Health Statistics (NCHS) conducts the NMFS to collect information about persons who die in the United States. The NMFS conducted most recently (1993) was the first version to elicit firearm ownership information and to include decedents younger than 25 years.38 The decedents (n=22,957) were sampled from the Current

Results

The homicide analysis used 1,720 case subjects and 8,084 control subjects. Table 1 presents demographic characteristics.

. Characteristics of homicide case subjects 18 years old or older who died in 1993 and living control subjects.

CharacteristicsHomicide
Case Subjects,* % (N=1,720)Control Subjects, % (N=8,084)
Demographic characteristics
Sex
Female15.825.2
Male84.274.8
Race
White43.070.5
Black54.125.8
Other2.93.7
Age, y (mean±SD)33.1±13.538.4±14.6
Lived alone19.724.3
Marital status
Never married57.230.2

Discussion

A gun in the home is a risk factor for gun-related homicide and suicide among this sample of adults in the United States. A gun, when available, might be chosen over a less lethal method to commit suicide.51 This might explain why the presence of a gun at home emerges as a risk factor for gun-related suicide and is inversely associated with suicide by means other than a gun. The increased risk for gun-related homicide might emerge because a gun can make an assault easier to attempt (because it

Acknowledgements

I thank Susan B. Sorenson, PhD, for conceptual advice; Colin Loftin, PhD, for suggesting the NHIS for living control subjects; Hal Morgenstern, PhD, for methodological advice; Lois Takahashi, PhD, Katherine Vittes, MPH, and Catherine Taylor, MPH, MSW, for constructive feedback; the University of California-Los Angeles Academic Technology Services consultants; and anonymous reviewers for their contributions. The paper extends my dissertation research. For that work, I am indebted to Joan

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    • Firearm ownership, attitudes, and safe storage practices among a nationally representative sample of older U.S. adults age 50 to 80

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      Citation Excerpt :

      While 84% of these deaths result from suicide, firearm suicide and homicide rates have both increased among older adults in the past decade, signifying a need to focus greater attention on firearm injury prevention among this population. Ecologic studies demonstrate an association between firearm availability and adult firearm suicide and homicide rates (Miller et al., 2002a; Miller et al., 2002b; Dahlberg et al., 2004; Kellermann et al., 1992; Wiebe, 2003a; Hemenway and Miller, 2002; Miller et al., 2007; Sloan et al., 1988; Markush and Bartolucci, 1984; Marzuk et al., 1992), as well as with unintentional firearm fatality rates across the age spectrum (Miller et al., 2002c). Case control studies provide individual-level evidence that firearm ownership increases homicide and suicide risk (Kellermann et al., 1992; Kellermann et al., 1993; Bailey et al., 1997; Cummings et al., 1997a; Conwell et al., 2002), including for older adults (Conwell et al., 2002), suicide risk among adolescents (Brent et al., 1988), and unintentional firearm deaths in children, adolescents, and adults, including older adults (Wiebe, 2003b).

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    Dr. Wiebe is currently affiliated with the Department of Biostatistics and Epidemiology, Firearm Injury Center at Penn (FICAP), and the Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, PA.

    ☆☆

    This work was supported at the University of California-Los Angeles in part by a grant from The California Wellness Foundation (TCWF). Partial funding was provided also by Public Health Foundation Enterprises, Inc., through a grant from The California Endowment. The original dissertation research was funded in part by a grant from the School of Social Ecology at the University of California-Irvine.

    Address for reprints: Douglas J. Wiebe, PhD, Department of Biostatistics and Epidemiology, University of Pennsylvania, 933 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021; 215-746-0149, fax 215-573-2265; E-mail [email protected].

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