The Future of Children, Princeton - Brookings: Providing research and analysis to promote effective policies and programs for children.

The importance of injuries as a leading killer of children has been recognized for centuries. Until recently, injuries were commonly referred to as “accidents.” As advocates struggled to bring injury control into the public health domain, however, the word “accident” was recognized as a barrier.⁶ The dictionary defines “accident” as “a happening that is not expected, foreseen, or intended; a chance or fortune.” These meanings imply randomness and lack of predictability, and they defy a specific causal model. In fact, as early advocates of injury control concluded, the opposite is true of injuries.⁷

The more accurate term of “injury” is defined as the transfer of kinetic, thermal, radiation, or chemical energy to the human body, leading to tissue damage and destruction at a cellular level. The definition has been expanded to include drowning and choking/asphyxiation, although the transfer of energy causes neither of these mechanisms. Injury occurs when the amount of energy transferred to the body exceeds the maximum tolerance for affected tissue. The severity of an injury should be predictable, following the principles of biology and physics, and not random. Similarly, science has helped to further dispel the myth of “randomness” of injuries by identifying specific factors, known as risk or protective factors, that elevate or reduce the likelihood of sustaining an injury. The identification of risk and protective factors is a crucial prelude to any credible intervention to reduce the incidence or severity of injuries.

The paradigmatic shift of redefining “accidents” as “injuries” was based on refuting the concept of “accident proneness” among children as an explanatory model for childhood injury.⁸ A dominant theory of childhood injury in the first half of the twentieth century, accident proneness framed the risk of injury as an individual trait. This theory conflicted sharply with traditional public health approaches to disease and prevention, which focused on children's interactions with their environment. As the modern concept of injury control took hold, its multidisciplinary nature began to emerge. Injury control efforts became defined as both the prevention of injury by a diverse group of professionals, such as engineers, city planners, and behavioral scientists, and the mitigation of injury effects by health care professionals working in acute care and rehabilitation settings. Although these efforts found a natural home within the framework of biomedicine, injury prevention seemed naturally suited for the public health profession as well.

The emergence of injury prevention as a public health discipline guided by science was grounded in these basic semantic shifts. For public health practitioners to make progress, they would have to convince the public and policymakers that injuries were as amenable to control as were diseases. Public policy efforts to reduce motor vehicle injuries became early models of the current injury prevention paradigm.⁹

Motor Vehicle Safety

During the 1960s, groups of doctors and engineers were beginning to address widespread concern regarding occupant injuries from motor vehicle crashes. The postwar economic boom that made automobiles widely available to the U.S. public also led to a steady rise in fatalities and injuries resulting from crashes. The prevailing view—that drivers were largely responsible for these injuries and that injury countermeasures should focus on improving driver behavior—was challenged by a small number of skeptical physicians and engineers.^10,11 Using observations from airline safety strategies, these advocates began to focus on automobile design as an important component of occupant safety. They argued that, if crashes could not be prevented, designing more crashworthy cars and promoting the use of seat belts could still reduce injuries.

The publication of Ralph Nader's book about the Corvair, Unsafe at Any Speed: The Designed-in Dangers of the American Automobile, led to intense scrutiny of car safety by politicians and consumer advocates.¹² This investigation resulted in the National Traffic and Motor Vehicle Safety Act and the Highway Safety Act, signed by President Lyndon Johnson in September 1966. These acts, and the people charged with carrying out their intent, largely redefined injury control as a public health issue during the remainder of the century.

The first large-scale involvement by the federal government in civilian injury prevention came when the National Highway Safety Bureau was created in 1966 under the National Traffic and Motor Vehicle Safety Act.¹² William Haddon, a physician who strongly advocated the public health approach to injury prevention, was appointed as the first director of the bureau. Under Dr. Haddon's leadership, injury prevention efforts shifted from changing individual behavior toward changing the agent (for example, the motor vehicle) and the environment (for example, highway design).

Haddon developed a conceptual matrix model of motor vehicle injury prevention that focused on the host (for example, driver), the agent, and the environment at three different temporal phases of the crash: before, during, and after (see Table 4).¹³ Although Haddon's matrix was conceptualized as an approach to motor vehicle occupant injury, it has become a model for the prevention of many types of injuries among children and adults. Using pedestrian injury as an example, factors addressed in a matrix could include human factors (pedestrian intoxication), agent characteristics (high-profile car grille), environmental factors (absence of sidewalks), and sociological factors (auto advertisements that promote vehicle speed). Opportunities to prevent morbidity and mortality due to crashes could be present at one or more of three different time intervals: before, during, and following the crash.

Most safety activities at the time focused on decreasing the risk of a crash by focusing on driver behavior. Too little attention had been paid to improving cars to make crashes more survivable or to changing highway design to lessen the chance of a crash. Haddon's focus on potential vehicle improvements led to the creation of federal standards for motor vehicle design and safety equipment—including stronger vehicle occupant cages, collapsible steering columns, shatterproof glass, padded interiors, and safety belts—aimed at decreasing the risk of injury when crashes occur. The postcrash phase of injury control focused mainly on acute care of injuries and stimulated federal involvement in the creation and support of emergency medical response and trauma systems. Importantly, Haddon's model embraced a multidisciplinary approach to injury prevention by integrating the work of behavioral scientists (to address driver behavior and societal norms), engineers (to address changes to vehicle and highway design), and physicians (to address the acute care and rehabilitation of injured patients).

The Expansion of Product Regulation

Federal involvement in automotive safety signaled a novel interest on the part of the government in broader product safety issues.¹⁴ Before product liability represented a serious concern for manufacturers, medical and public health experts began to apply the same analytic strategies and preventive approaches to other major causes of childhood injuries related to consumer products, such as the ignition of children's sleepwear (see the article by Schieber, Gilchrist, and Sleet in this journal issue). An independent federal regulatory agency, the U.S. Consumer Product Safety Commission (CPSC), was created by Congress in 1972 to “protect the public against unreasonable risks of injuries and deaths associated with consumer products.”¹⁵ (The CPSC today has jurisdiction over about 15,000 types of consumer products, from automatic-drip coffeemakers to toys to lawn mowers.) With the creation of the CPSC, childhood injury prevention had clearly moved toward improving children's environments. Advocates had learned that influencing legislation and administrative agencies provided a powerful and necessary tool to effect change.

Capacity to Monitor Childhood Injuries

The cornerstone of a strong public health system is the capacity to conduct ongoing surveillance of targeted conditions in the population.¹⁶ Surveillance provides data to prioritize health problems, evaluate interventions and programs, and recognize new epidemics. Until recently, scientific advancements in injury prevention programs were stymied by a lack of high-quality surveillance data.¹⁷ Anatomic descriptions of injuries (for example, arm fracture or liver laceration) have always been available in mortality and hospitalization data, but the paucity of injury mechanism data has prevented researchers from gaining a richer understanding of possible causes. The rise of injury control, however, led to wider adoption of the “external cause of injury” code system for the International Classification of Diseases (ICD). These codes attribute injuries to one or more specific mechanisms (for example, pedestrian in traffic), and they are used in hospital and emergency department records and on death certificates to describe cause of injury.

Where they are used, external cause of injury codes have provided enormous insight into the leading causes of injury mortality. The U.S. National Center for Health Statistics (NCHS) requires death certificates that document an injury-related death to include the external cause code. The need for nonfatal injury data is paramount, however, since for every injury death it is estimated that an additional 15 to 20 hospitalizations and 200 to 250 emergency department visits occur.³ Unfortunately, external cause of injury codes are not used universally by hospitals for coding discharge data. As of 1997, some 23 of the 36 states that routinely collect some level of external cause of injury codes (63.9%) have mandated this coding in their statewide hospital discharge data system.¹⁸

As progress is made toward reducing preventable injury deaths, the focus of public health efforts will shift to reducing and mitigating severe nonfatal injuries. Unfortunately, there are few population-based data available for monitoring injury mechanisms that lead to emergency department visits. External cause of injury codes are often unavailable from emergency records and are infrequently coded on billing data. Only 11 states have developed the capacity to provide external cause of injury coding data on statewide emergency department data systems.¹⁹ Aside from death certificates and hospital and emergency department data, other large surveillance systems also exist to provide sound data on the epidemiology of childhood injury in the United States and other parts of the world (though a detailed description of each of these surveillance systems is beyond the scope of this review).

In summary, problems remain with regard to access to injury prevention surveillance data. The first problem is the lack of adequate data regarding nonfatal injuries. The second barrier is obtaining access to community-specific data. Significant geographic variations in injury rates occur, and national statistics are not always useful to policymakers in states and communities. Although Internet technologies (such as the Centers for Disease Control and Prevention's WONDER project, an interactive Web site that provides county-specific injury mortality data ²⁰ ) have made access to local data easier, further strides should be made to improve access. Finally, the inconsistency of content and quality among injury surveillance databases makes comparisons of impact and outcomes difficult. For example, there are excellent national data systems for surveillance of and research on motor vehicle injury, but firearm surveillance systems are at a more primitive stage.²¹