Consistent with previous individual level studies,2,3,4,5,6,7,8,9,10,11,12,14,15
as well as with some17,18,20,21,22,23,24,29,52
but not all19,25
cross sectional ecologic studies, we find that higher rates of firearm ownership are associated with higher rates of overall suicide. For all groups, the relation between changes in household firearm ownership and changes in overall rates of suicide is due to the association between changes in firearm ownership and changes in suicide by firearms (that is, changes in non‐firearm suicide are not related to changes in rates of firearm ownership). Our finding that the magnitude of association between household firearm ownership and suicide is particularly high for children is consistent with previous empirical work,10,19,23,53
and with the hypothesis that suicide acts by youth are more likely to be impulsive and therefore more likely to be affected by the means at hand.54,55
Our findings are also consistent with some31,32,33
but not all,30,34
previous national longitudinal studies (all but one of which examined the relation between suicide rates and firearm related legislation rather than the relation between suicide rates and firearm prevalence directly). Relative to previous US studies, our longitudinal study focused on a time period during which there was a marked downward trend in household firearm prevalence. This statistical advantage made it less likely that an actual association between firearm prevalence and rates of suicide would be obscured by random error involved in measuring firearm prevalence. This advantage may explain, in part, why we found a significant relation between changes in firearm prevalence and rates of suicide when the only previous US study to directly investigate the association between firearm prevalence and suicides found none.30
In addition, that previous study did not control for other factors and used firearm ownership data from two different sources (Gallop and NORC polls) over a period during which firearm prevalence changed little relative to the measurement error associated with estimating prevalence.
The current study is the first longitudinal evaluation we are aware of to specifically render the exposure of interest—household firearm prevalence—separately for men, women, and children. By doing so we are better able to account for the possibility that changes in household firearm prevalence might differ for these distinct groups (as might have occurred, for example, because of changes in household composition over time). In addition, we are able to control for potential regional variation in rates of change in firearm prevalence and suicide over time.
Although our ecologic approach avoids the case control problem of recall bias (for example, cases being more likely to accurately recall a firearm in the home than controls), this benefit comes at the possible interpretative cost of assuming that group‐level associations reflect individual risk factors (that is, the ecologic fallacy).56
The greatest threat to the validity of our findings in this respect is that we do not know whether firearm suicide victims actually lived in homes with guns. Findings from case control studies, however, suggest that firearm suicide victims overwhelmingly use guns from their own home.2,3,4,5,6,7,8,9,10,11,12,14,15
For example, in one study of suicides in the home10
and in another of adolescent suicides in and out of the home,6
approximately 90% of victims used a gun if they lived in a home with a gun. In addition, fewer than 10% of all firearm suicides involved a firearm from a home other than the victim's household.10
Our analyses adjust for rates of poverty, unemployment, per capita alcohol consumption, the age distribution of the population, and census region, but many other factors may affect suicide rates. We could think of no obvious covariates that, were they included, would a priori explain the specificity of our findings—that changes in firearm
suicide (but not non‐firearm suicide) correlate with changes in firearm ownership. The covariate we most would have liked to directly account for in our analyses is one that captured annual changes in suicidality over time. Unfortunately, no such data are available. However, the largest study ever to address secular trends in the mental health of Americans found no national changes in suicidal tendencies between 1990 and 200057
—precisely the period of our study during which suicide rates (and firearm ownership) declined most steeply. In addition, previous cross sectional ecologic studies have found that measures of psychopathology (for example, major depression, serious suicidal thoughts) do not appear to be associated with rates of household firearm ownership29
and that controlling for suicide attempt rates does not mitigate the gun‐suicide connection.53
Our study has additional limitations. Although we used survey measures of household firearm ownership, this measure does not provide potentially important information about many characteristics of firearm availability that may be related to the rate of suicide deaths. For example, our measure does not provide information about the relative prevalence of handguns and long guns, the number of firearms in a gun owning household, firearm storage practices, access to illegal firearms, familiarity with firearms, the caliber of gun(s), how often guns are used for other purposes such as hunting or target practice, or changes in the social acceptability of suicide by firearms over time. In addition, survey research has found that many women, some living in two‐adult households with guns, may not have accurate information about whether a gun is present in their home.48,58
That we find significant associations between suicide and firearm prevalence regardless of whether prevalence estimates are derived from men or women or all respondents suggests that reporting differences by gender do not account for our results.
Despite these limitations, we find changes in household firearm ownership over time were associated with significant changes in rates of suicide for men, women, and children, controlling for the region of the country in which they lived and independent of rates of unemployment, poverty, and alcohol consumption. The relation between changes in household firearm ownership and overall rates of suicide is due to the association of firearm ownership and suicide by firearms (that is, changes in non‐firearm suicide are not related to changes in firearm ownership). Consistent with our findings, a recent systematic review of all suicide prevention studies published between 1966 and 200559
concluded that restricting access to lethal means is one of only two suicide prevention strategies shown to prevent suicide. This conclusion, however, is at odds with the view held by many Americans—that restricting access to highly lethal means is unlikely to save many lives.60
The presumption is that anyone serious enough about suicide to use a gun or jump off a bridge will inevitably find another way to take his own life. Results from our longitudinal study, combined with findings from previous case control, cohort, and ecologic studies fundamentally undercut this presumption. In a nation where over half of all suicides are due to guns, restricting ready access to household firearms is likely to save many lives, especially among children.
- Consistent with previous cross sectional case control and ecologic studies, this time series analysis finds a significant relation between household firearm ownership and rates of suicide overall and by firearms.
- Changes in household firearm ownership over time are associated with significant changes in rates of suicide for men, women, and children.
- These findings suggest that reducing availability to firearms in the home may save lives, especially among youth.