SUMMARY AND RECOMMENDATIONS

The committee draws the following conclusions on the basis of the

present evidence:

1. States, regions, and countries with higher rates of household gun

ownership have higher rates of gun suicide. There is also cross-sectional,

ecological association between gun ownership and overall risk of suicide,

but this association is more modest than the association between gun ownership

and gun suicide; it is less consistently observed across time, place,

and persons; and the causal relation remains unclear.

2. The risk of suicide is highest immediately after the purchase of a

handgun, suggesting that some firearms are specifically purchased for the

purpose of committing suicide.

3. Some gun control policies may reduce the number of gun suicides,

but they have not yet been shown to reduce the overall risk of suicide in any

population.

TABLE 7-6 Quasi-Experimental Studies of Gun Laws and Suicide

Areas and

Time

Period

Source Compared Gun Law Population

Reuter and Australian 1996 gun buy- Whole population

Mouzos states, back

1979-1998

Ludwig and 50 states 1994 Brady act 21-54 years

Cook (2001) + DC

1985-1997 55+

Lott and 50 states Safe storage laws Children and

Whitley + DC adolescents 0-19

(2000) 1979-1996 Other gun laws

Cummings, 50 states Safe storage laws Children under 15

Grossman, + DC

Rivara, and 1979-1994

Koepsell

(1997a)

There are several substantive differences between the research literature

linking guns and crime and the research literature linking guns and suicide.

First, there is a cross-sectional association between rates of household gun

ownership and the number and fraction of suicides committed with a gun

that appears to be much more consistent than, for example, the crosssectional

association between gun ownership and gun homicide. There also

appears to be a cross-sectional association between rates of household gun

ownership and overall rates of suicide, reported by investigators on both

sides of the gun policy debate. However, the association is small, the findings

seem to vary by age and gender, and results have been sensitive to

model specifications, covariates, and measures used; furthermore, the association

is not found in comparisons across countries. In the absence of a

simple association between household gun ownership and crime rates within

the United States, the literature on guns and crime has been forced to attend

to some of the methodological problems of omitted variables and endogenous

relationships inherent in studying complex social processes. The presence

of a simple bivariate association between gun ownership and suicide

may have prevented suicide investigators from pursuing study designs hav-

Change in Change in Change in

Gun Suicide Nongun Suicide Overall Suicide

After Gun Law After Gun Law After Gun Law

Continuation of Continuation of Increase

of decreasing trend increasing trend

No significant No significant No significant

difference difference difference

Decrease No significant No significant

difference difference

Mixed: Not stated No significant

Decrease with difference

higher age limits

Not stated No significant

mixed differences

(see text)

No significant No significant No significant

difference difference difference

ing a better hope of justifying a causal inference. The issue of substitution

has been almost entirely ignored in the literature of guns and suicide.

Some of the problems in the suicide literature may also be attributable

to the intellectual traditions of the injury prevention field, which has been

strongly shaped by successes in the prevention of car crashes and other

unintentional injuries. An unintentional injury prevention model can lead

to misunderstandings when it is applied to the study of intentional injury;

the investigation of intentional injury should take account of the complexities

of preference, motivation, constraint, and social interaction among the

individuals involved.

In addition to better addressing these fundamental problems associated

with drawing causal inferences, this chapter has highlighted a number of

other data and methodological obstacles. What sort of data and what sort

of studies would be needed in order to improve the understanding of the

association between firearms and suicide? Although some knowledge may

be gained from further ecological studies, the most important priorities

appear, to the committee, to be improved data systems, improved individual-

level studies of the association between gun ownership and suicide,

and a more systematic analysis of the effect of firearms laws and related

interventions on the risk of suicide.

Proxy Measures of Gun Ownership

The association between gun ownership and gun suicide has led to

recommendations for the use of the fraction of suicides committed with a

firearm (FS/S) as a proxy for household gun ownership when direct measures

are unavailable. This means that a better understanding of the relationship

between firearms and suicide may also make a technical contribution

to the study of firearms and crime. However, investigators should be

aware of the biases that can be introduced by any proxy measures, and they

are warned that particularly serious artifacts can be introduced if FS/S is

used as a proxy for gun ownership when suicide is also the outcome of

interest.