Worldwide, motor vehicle collisions have been producing more than 1 million deaths and 38 million injuries each year—losses projected to increase substantially by 2020.1 These high rates are partly the result of the lack of standards for vehicle crashworthiness in economically poorer countries. The high rates also reflect more collisions involving pedestrians and nonmotorized vehicles in poorer countries.2 However, even in the United States, motor vehicle crashes account for approximately 42,000 deaths and 3 million injuries a year. Because those killed are 4 decades younger, on average, than those who die of cardiovascular diseases or cancer, the toll on the nation’s economic and social health is disproportionately large.
The mortality figures in wealthy nations would be much worse without the work of injury epidemiology. Epidemiologists have contributed data influencing the enactment of child restraint and belt use laws, more effective alcohol laws and enforcement strategies, and identification of characteristics of vehicles or highways that increase the risk of severe injury. It is therefore ironic that this subject is absent from the curriculum in many epidemiology training programs. Only a few schools cover the full range of issues regarding research design, measurement, and implications for injury reduction.
Two papers in the current issue of the journal illustrate some of the difficulties.3,4 The study of alcohol involvement3 used controls that were not necessarily driving at the same times of day and week and in the same places. Control of time and place has characterized the best case-control studies. Alcohol involvement is concentrated at certain times of the day and days of the week and on certain roads. Thus, a comparison with drivers in the general driving population does not truly assess the contribution of alcohol to increased risk under given specific driving conditions. The study of alcohol involvement, already well known, is less useful than the study of where and when alcohol-related crashes occur. The latter can be used to deploy law enforcement more efficiently to arrest drunk drivers and enforce laws against serving the underaged or the inebriated.
A second study in this issue looks at seating position of children in motor vehicles.4 Here, the purpose is to identify factors associated with children riding in more risky seating positions. The study relies on self-reported behavior, which could not be valid. The authors hope to contribute to better-designed educational efforts, but might also have considered research that indicates such behavior is more strongly influenced by laws than by education.5
As more sophisticated methods are put to work, straightforward questions could be missed. I once attended a PhD dissertation defense after which an attendee said, “You people are more interested in how you found it than in what you found.” We should not be. Relatively simple descriptive studies are often adequate to improve injury control. Information on the “who, when, where, and how” of injuries can lead to countermeasures that efficiently target population, time, place, or mechanism. Visits to sites where injuries cluster often reveal obvious hazards. Where the effects of countermeasures are unproved, well-designed epidemiologic studies can cull the effective from the ineffective. Complex analytical models and research designs could be more fun intellectually, but they do not necessarily contribute more to injury control than do simple descriptive studies and evaluations of countermeasures.
ABOUT THE AUTHOR
LEON S. ROBERTSON is a retired injury epidemiologist. He has served on the faculties of Yale University, Harvard University, and Wake Forest University, and he worked for 8 years in the Insurance Institute for Highway Safety. He is the author of the book Injury Epidemiology, the latest edition of which was published by Oxford University Press in 1998.
1.Murray CJL, Lopez AD, eds. The Global Burden of Disease
. Cambridge: Harvard University Press; 1996.
2.Berger LR, Mohan D. Injury Control: A Global View
. Delhi: Oxford University Press; 1996.
3.Connor J, Norton R, Ameratunga S, Jackson R. The contribution of alcohol to serious car crash injuries. Epidemiology
4.Durbin DR, Chen I, Elliiott M, Winston FK. Factors associated with front row seating of children in motor vehicle crashes. Epidemiology
. 2004;15: 345–349.
5.Robertson LS. Injuries: Causes, Control Strategies and Public Policy
. Lexington, MA: DC Heath; 1983.