Complementary Strategies to Prevent Firearm Injury

Recent research on the topic of firearm injury prevention^{1 - 3} has evaluated the effect of policies intended to limit access to firearms by individuals who are at increased risk of assaulting someone else. One assumption underlying this approach is that the severity of assault injuries may be decreased if available weapons are less lethal. Another assumption is that preventive strategies targeting persons at high risk may be feasible and effective.⁴

The study by Wintemute and colleagues⁵ in this issue of THE JOURNAL evaluated the effect of a targeted intervention that was designed to prevent the purchase of handguns by individuals who were determined by screening⁴ to be at increased risk for assaulting someone else with a firearm. Specifically, the study evaluated the effect of a California law that prohibits handgun purchases by individuals who had been convicted of violent misdemeanor offenses. The authors compared the subsequent criminal histories of misdemeanants who were permitted to purchase handguns (before the purchase ban took effect) with misdemeanants who were prohibited from purchasing handguns. After controlling for other risk factors, Wintemute et al found that the denial policy resulted in a reduction in new arrests for violent or gun offenses.

Although the proportion of all firearm injuries in California likely to be prevented by this law may be small, the law may have additive or even synergistic effects when combined with other interventions, such as gun-targeted policing² (a targeted intervention) or restrictions on the secondary market for guns^{6 - 7} (a population-based intervention), assuming that secondary market restrictions will be enacted and evaluated to be effective. By analogy, complementary interventions have been observed to reduce morbidity and mortality from motor vehicle crashes.⁸ This reduction in motor vehicle crash mortality has been attributed to a combination of population-based interventions (eg, safety belts) and interventions targeting high-risk individuals, such as those who drive under the influence of alcohol.

A disadvantage of prevention strategies that target high-risk individuals is that those thought to be at low risk may account for much of the morbidity and mortality⁴ from a specific cause of injury or illness. Therefore, population-based strategies are also important, especially when risk factors are difficult to identify by screening because they are occult (substance abuse disorders, for example) or ubiquitous (ownership of guns). In theory, population-based strategies may even be preferable to targeted strategies⁴ because their potential effects are not limited to specific individuals and those they may assault. In practice, however, population-based and targeted strategies are often complementary.

Strategies targeting high-risk gun users may be further classified as methods for reducing supply or demand. For example, the intervention evaluated by Wintemute et al reduced the supply of guns to individuals convicted of misdemeanors. This supply-side approach⁷ for reducing gun violence is based on the assumption that the timing of gun availability influences the flow of guns into the hands of dangerous persons. Under this assumption, it is simplistic to assume that cutting off the flow of legal handgun purchases merely redirects handgun buyers to the secondary market for guns that are stolen or purchased legally for resale to prohibited buyers. Since about one third of all guns involved in crimes are recovered by law enforcement within 3 years of their first retail purchase,⁹ illegal diversion of legally sold guns accounts for a substantial fraction of the guns available in the secondary market. As this supply of guns to the secondary market is curtailed, the availability of guns to dangerous individuals is likely to be restricted, although this hypothesis still awaits scientific testing. Moreover, the supply via this secondary gun pipeline may not have to be stopped completely to deter firearm violence. Since many assaults are situational, spontaneous, or influenced by intoxication,¹⁰ reducing the flow of guns to a trickle may be sufficient to deter many firearm injuries.

Supply-side interventions may be complemented by disincentives for dangerous individuals to purchase, own, or carry firearms. As the supply of guns is decreased, the price of guns is likely to increase, affecting demand for guns by those with marginal incomes (such as persons with addictions to illegal drugs). Stiffer sentences for gun use in crime¹¹ and gun-targeted policing² may also reduce demand. The premise of gun-targeted policing is that if gun carrying increases the likelihood of arrest, then fewer individuals will carry guns illegally, and if the risk of arrest also deters other dangerous persons from carrying guns, there is less chance of a lethal confrontation and less demand for guns. In addition, some evidence suggests that defensive gun use may deter violence,¹² and that the enactment of laws permitting law-abiding citizens to carry guns legally preceded declines in the incidence of violent crime.¹³ Reconciling the views that gun carrying by law-abiding citizens may deter violence, but gun carrying by dangerous individuals can have the opposite effect, is a continuing major challenge for firearm injury research.²

Many other questions challenge researchers as well. More research is needed to describe firearm supply and demand within specific markets of potentially high-risk individuals, such as violent criminals, adolescents, those who perpetrate or defend themselves against intimate partner abuse, and individuals with certain forms of mental illness who already may be prohibited from purchasing firearms. More research is also needed to disentangle the effects of waiting periods and background checks for handgun purchase.¹ More evidence is needed that community interventions to deter high-risk drinking may reduce the incidence of assault injuries.¹⁰ In addition, researchers should attempt to confirm the results of Wintemute et al⁵ to learn whether these outcomes are specific to California or the period of their study. Beyond these challenges, more evidence is needed that the independent effects of interventions to prevent firearm injury may combine strategically to keep guns from falling into the wrong hands at the wrong time.

From a public health perspective, the adoption of interventions to thwart gun violence should not be based on strategic theory, but on empirical evidence of what works. Strategies, without evidence, can only illuminate hypotheses. Wintemute et al⁵ have provided solid evidence that denying handguns to individuals who have been convicted of violent crimes—whether misdemeanors or felonies¹⁴ —prevents subsequent violence. Unless better evidence proves otherwise, this intervention works. However, there is more work to be done. Strategies that address populations, high-risk groups, firearm supply, and firearm demand suggest that many other complementary interventions remain to be tested individually or in concert for their effectiveness in reducing the incidence of firearm injury.