Injury and its repercussions have a significant impact on health and well-being. Each year, more than 150,000 people die from injuries in the United States and more than 5 million people die from injuries worldwide.¹ It is the leading cause of death for Americans younger than 45 years and the burden of injury is not limited to deaths. Injury is a significant source of morbidity, disability, and disfigurement, generating substantial health care costs and lost productivity.²,³,⁴,⁵,⁶,⁷,⁸,⁹,¹⁰,¹¹

More than one third of all US emergency department visits, an estimated 39 million, are related to injury.¹² Each year, approximately one of every six Americans will require medical treatment for injuries and more than 2 million Americans will be hospitalized for injuries.⁸,¹³,¹⁴,¹⁵ In 2000, the total medical costs attributable to injury were estimated to be $117 billion, or approximately 10% of all medical costs in the United States.¹⁶

The estimated lifetime costs of injury for the >50 million Americans who experienced a medically treated injury in 2000 was $406 billion (inclusive of medical care and lost productivity).¹⁷ Disabling injury can have lasting impact. Each year an estimated 80,000 Americans experience the onset of long-term or lifetime disability from traumatic brain injury.¹⁸ And 11,000 new cases of spinal cord injury are estimated to occur annually, with more than 250,000 persons currently living with paraplegia, tetraplegia, or related disability.¹⁹,²⁰ The consequences of injury extend well beyond these physical disabilities. The repercussions of injury for individuals and families are profound, including decline in physical ability,²¹,²²,²³,²⁴ loss of work,²⁵,²⁶ loss of sexual function,²⁷ fatigue,²²,²⁸ and emotional health.²⁹

The circumstances of injury are often classified across two dimensions—intent (unintentional and intentional) and mechanism (e.g., motor vehicle, firearm, submersion, and fall).³⁰ Data on injury mortality and morbidity, classified by external cause of injury codes³¹ (formerly known as E codes³²), are categorized across these two dimensions. In the United States, motor vehicle traffic injuries (27%) are the leading cause of injury deaths, followed by poisoning (18%), firearm (18%), falls (12%), and suffocation (8%).⁹,³³ The five leading causes of injury deaths in those younger than 15 years are motor vehicle, fire and burns, drowning, suffocation, and firearm-related deaths. For youth and young adults, aged between 15 and 24, and older adults, aged between 65 and 74, traffic-and firearm-related injuries are the leading cause of injury death. Among adults older than 85 years, falls become the most important injury mechanism.

Injury differs from many other leading diseases, making injury control and its study particularly challenging: violence, falls, and automobile crashes all are events that can suddenly kill or disable otherwise healthy people. For the most part, injury happens in a fraction of a second, often after sudden exposure to immediate risk factors. In the past, injury has often been thought of as the result of unavoidable accidents—neither preventable nor likely to yield to systematic study. A closer look at the possible causal paths for many injuries suggests that this does not need to be the case. While an injury event is quite
rapid and some risks may be almost simultaneous to the event, many injuries are likely to follow from a series of accumulating and converging risks for people, mechanisms, and environments, some of which span decades.³⁴ The multiple factors and risks involved in different injuries suggest areas of systematic study and multiple points for intervention. Finally, although there are immediate repercussions of an injury, there is also the potential for long-term consequences.³⁵

The nature of emergency care for serious injury, occurring under less than optimal conditions, presents unique challenges for research. A narrow time window for intervention coupled with limited patient information and the inability of patients to give their own consent can raise ethical complications for resuscitation research.³⁶,³⁷,³⁸ Emergency research studies that seek exception from, or waiver of, informed consent require consultation with the community and public notification to that community.³⁹ In the case of trauma care, geographic designations of community may not capture the population at risk.³⁶ Clinical injury research needs to be thoughtful in the development of pragmatic and ethically appropriate approaches to study design.

Successful response to injury, once it has occurred, is highly time dependent.⁴⁰ Serious injury is usually followed by an extremely limited window of time for preventing disability or death. In some instances the damage caused by injury can be mediated for the event itself, by a restraint system or helmet, for example. Medical care systems must quickly be mobilized. Successful responses require a working knowledge of the many body systems that are activated in response to an injury (biochemical, cellular, connective, organ, and psychological systems). The wide range of interconnected physiologic responses involved in the injury event, coupled with the need for extremely rapid medical care, is a research and methodological challenge to injury science. Published research on clinical practice guidelines reveals that retrospective studies and case reports dominate clinical trauma research, with only 4% of studies based on more methodologically rigorous randomized prospective designs.⁴¹

The complexity of elements relevant to an injury event, its risks, and its repercussions encompasses many spheres of knowledge, making injury science an important yet developing field of interdisciplinary research.⁴² Research is often conducted within a single discipline, without crossing boundaries of traditional knowledge domains. An analysis of systematic reviews of injury research from the Cochrane Collaboration and the Campbell Collaborative illustrates this point.⁴³,⁴⁴,⁴⁵,⁴⁶,⁴⁷ In these reviews, only 10 out of 48 (21%) involved more than one knowledge domain (e.g., biology and behavior or mechanism and environment). As a complex and uniquely challenging disease process, injury research has not yet leveraged the full potential of systematic, integrated, interdisciplinary research.

Injury as a field of public health has grown in size, scope, cohesion, and sophistication; there are now a wide variety of disciplines, specialties, and practitioners participating in the field of injury prevention and treatment.⁴⁸ Also important for the advancement of the field of injury control has been a growing connection between prevention and treatment.⁴⁸ Although debate continues on the boundaries of the field, the application of appropriate methods, and the degree of scientific rigor, there has been much progress.⁹

Is the prevention of intentional injuries a valid area of injury control research?⁴⁸ Some in the injury field see the inclusion of violence as a deviation from the field’s core mission, diverting resources needed for the study and prevention of unintentional injury. However, violence is increasingly being seen as a public health problem.⁴⁹ Indeed, there are calls to integrate injury research across intentional and unintentional causes to improve injury prevention and health.⁵⁰ This increasing interest by medical and public health professionals should not imply that injury control research should supplant criminology or mental health research, but rather it should complement the approaches of these and other fields.

Another tension in the field has been between active and passive approaches to injury prevention. Although the field initially focused on attempts to change individual behaviors, there was increasing skepticism about the effectiveness of individually focused behavioral interventions.⁴⁸ This skepticism, coupled with injury control advances in the 1960s, led to a shift toward passive interventions that focused on changing mechanisms and environment. In recent years, however, the field has begun to integrate both as complementary rather than competing approaches. In addition, scientists have also broadened the focus from individual behavior to societal behaviors that might mitigate risks.⁵¹

The field also suffers from tensions over tradeoffs with other important societal values—the relative costs of interventions and curtailment of freedom and policies perceived as paternalistic. Increasing research on cost-effectiveness and cost benefits is important to addressing these concerns, and the restriction of personal freedom should be considered as one of the potential costs of any intervention.⁴⁸

The approaches, resources, and tools of public health provide a scientific foundation for injury control science. To be fully effective, injury control needs coordinated efforts that build interdisciplinary studies in prevention and treatment.⁹ The advancement of injury science would benefit from a more systematic and methodologically rigorous approach across a range of inquiry, including genes, cells, organ systems, body, mind, individuals, social groups, and the environment. This integration across biology, environment and behavior can illuminate new ways to consider risk for injury.⁵² Research on the precursors of injury, the injury event, and the consequences of injury has tended toward descriptive studies or less methodologically rigorous designs.⁵³ Further, injury research generally focuses on
behavioral approaches for the precursors of injury, bioengineering approaches for the injury event, and clinical approaches for the consequences of injury. Injury research has not harnessed the full potential of the biomedical sciences. This limits our ability to significantly reduce the overall impact of injury, both in terms of prevention, mortality, and long-term repercussions.