Injury Epidemiology

Injury epidemiology involves characterization of occurrences of injuries, identification of risk factors, and the evaluation of prevention programs for injuries. Although the term injury could refer to almost any adverse health event, this term is generally used to refer to damage to human tissue resulting from exposure to energy delivered in excess of the threshold that human biological systems can tolerate. This excess transfer can occur during exposure to various forms of energy, including mechanical, chemical, electrical, and ionizing and nonionizing radiation. Injuries may also occur as a result of errant medical interventions and, in the case of strangulation or drowning, could result from the lack of an element vital to the body (i.e., oxygen). Injuries are often classified as either intentional (homicide, suicide, violence) or nonintentional (falls, motor vehicle crashes, burns, lacerations, strains, and cumulative trauma). Injury epidemiology is applied in various diverse environments such as the workplace, home, transportation, and sports and recreational settings.

The application of systematic epidemiologic methods in the analysis of injury events is a relatively recent phenomenon, with its origins in the early 1960s. Despite being a rather new field, injury epidemiology research has led to the development of numerous interventions (e.g., seat belts, bicycle and motorcycle helmets, ergonomic design improvements, workplace safety programs, automobile safety design, and transportation regulations) that have achieved [Page 538]significant public health improvements. Because one of the largest public health impacts of natural and man-made disasters (hurricanes, tornados, floods, earthquakes, volcanoes, drought, famine, war, terrorism) is injury, the field of disaster epidemiology involves the application of injury epidemiology methods as well as evaluation of infectious disease and mental health conditions.

Injuries have historically been referred to by terms such as accidents, mishaps, casualties, acts of God, or other terms that imply a random nature or unavoidability. In fact, most injuries show clear nonrandom patterns that can be characterized epidemiologically and have identifiable risk factors. In addition to prevention, research efforts have identified interventions that were subsequently implemented to reduce the consequences of injuries once they have occurred (e.g., seat belts, airbags). The field of injury epidemiology observes a distinction, similar to that in medicine, between ‘acute’ injury and chronic injury, repetitive injury, or cumulative trauma. There is currently a debate in the field as to whether terms such as acute injury and chronic injury should refer to the time period for the delivery of exposure or the duration of the injury. Also, in some circumstances, cumulative trauma has been classified as a disease rather than an injury. However, when injury is defined as the result of excess energy transfer beyond a tolerance threshold (whether this is delivered suddenly or over a long period of time), logically cumulative trauma should be considered as a type of injury. Until a standard terminology is adopted for injury labels such as acute or chronic, epidemiologists should clearly define the meaning of their injury terminology to avoid confusion and to assure better comparability of results across different studies.