Injuries are a leading cause of death and disability around the world. In 2010, injuries killed 5.1 million people globally, corresponding to a rate of 73.6 per 100,000 people. Figure 2-1, A shows the relative distribution of global deaths, from communicable diseases (Group A, in red ), noncommunicable diseases (Group B, in blue ), and injuries (Group C, in green ) in 2010. The area each box represents is proportional to the associated mortality. Of the 52.8 million people who died in 2010, almost 10% died due to an injury (Group C, Fig. 2-1, A ). In addition to deaths, nonfatal injuries result in substantial disability. Public health researchers use disability-adjusted life years (DALYs) lost ( Box 2-1 ), to quantify the total public health burden of ill health. DALYs provide a comparable measure of the health loss due to fatal and nonfatal diseases and injuries. Figure 2-1, B shows the relative distribution of global DALYs, from communicable diseases (group A, in red ), noncommunicable diseases (Group B, in blue ), and injuries (Group C, in green ) in 2010. The area each box represents is proportional to the associated burden of disability. In 2010, 11.2% of the global DALYs lost from all causes were due to injuries (Group C, Figure 2-1, B ).
The statistical estimates presented in this chapter are from the Global Burden of Disease, Injuries, and Risk Factors (GBD) Project. In 1991, the World Bank commissioned the first GBD study to develop a comprehensive and comparable assessment of the burden of 107 diseases and injuries and 10 selected risk factors for the world and eight major regions. The findings represented a major improvement in global knowledge of population health metrics and proved to be influential in shaping the global health priorities of international health and development agencies. The study also stimulated numerous national burden-of-disease analyses that have informed national debates on health policy over the last two decades.
The current revision of the study, GBD 2010 is a comprehensive update of the original study and presents estimates for 291 diseases and injuries, 67 risk factors, and 1160 sequelae (nonfatal health consequences) disaggregated by sex and 20 age groups for 21 regions covering the entire globe. The study is a collaboration of hundreds of researchers around the world, led by the Institute for Health Metrics and Evaluation at the University of Washington and a consortium of several other institutions including: Harvard University, Imperial College London, Johns Hopkins University, University of Queensland, University of Tokyo, and the World Health Organization.
Diseases and injuries result in either premature death or life lived with ill health. GBD aims to quantify the gap between the ideal of a population that lives a full life in full health and the reality. GBD uses the following concepts to measure this health burden:
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Years of Life Lost (YLL): This is the number of years of life lost because of premature death. It is calculated by multiplying the number of deaths at each age by a standard life expectancy at that age.
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Years of Life with Disability (YLD): This is number of years of life that are lived with short-term or long-term health loss weighted by the magnitude of the disability due to the sequelae of diseases and injuries.
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Disability-Adjusted Life Year (DALY): This is the main summary measure of population health used in GBD to quantify health loss. DALYs provide a metric that allows comparison of health loss across different diseases and injuries. They are calculated as the sum of YLLs and YLDs. Thus they are a measure of the number of years of healthy life that are lost due to death and nonfatal illness or impairment.
Over the past two decades, global population health is in the midst of a transition away from communicable, maternal, neonatal, and nutritious disorders (Group A causes) and toward noncommunicable diseases and injuries. While the number of deaths from Group A causes declined by 17% from 1990 to 2010, deaths from injuries in that period rose by 24%. The extent of this global health transition varies across global regions. While only 6.3% of the health burden in developed regions now is due to Group A causes, in developing regions these causes currently account for 40.2% of the burden. However, despite the shifts in communicable causes, injuries are a major threat even in the poorest regions of the world. For example, in sub-Saharan Africa, injuries account for 7.8% of the health burden, which is only a little less than Western Europe (9.1%).
Globally, 3 of the top 25 leading causes of years of healthy life lost (measured in DALYs lost) are due to injuries, including road injuries (ranks tenth), self-harm (ranks eighteenth), and falls (ranks nineteenth) ( Fig. 2-2 ). Two other major drivers of disability, low back pain (ranks seventh) and other musculoskeletal (ranks twenty-third) are also likely to reflect primarily injury and trauma. However, the rankings can vary dramatically across different regions. For example, road injury is a top five cause of DALYs lost in seven global regions, including second overall in Andean Latin America. Falls and self-harm are top five causes of DALYs lost in Central Europe and the high-income Asia–Pacific regions, respectively. Low back pain, which we believe has primarily an injury etiology, is a top five cause of DALYs lost in 11 regions of the world, although it tends to rank lower in sub-Saharan Africa.
Causes of Injury
Road traffic crashes kill 1.33 million people annually and result in 77 million DALYs lost. They are the eighth leading cause of death, eighth leading cause of life years lost, and the tenth leading cause of DALYs lost globally. In 2010, road injuries killed more people than tuberculosis and malaria, two diseases that have been a central focus of the global health agenda. Road injury deaths have grown by 46% since 1990 (rates grew by 12%). Road traffic crashes are the leading cause of injury deaths, accounting for more than a quarter of all injury deaths ( Fig. 2-3 ).
Violence, self-inflicted and interpersonal, together killed another 1.33 million people in 2010. Intentional self-harm was the thirteenth leading cause of death among all causes, killing 0.88 million people. It is the second leading cause of injury deaths, accounting for 17% of injury deaths. Interpersonal violence (homicide) killed 0.45 million people in 2010, accounting for 9% of injury deaths. Although total homicides grew by 35% since 1990, this was slower than the rate of population growth during this period.
Falls were the third leading cause of injury deaths, resulting in 0.54 million global deaths in 2010, 11% of all injury deaths. Deaths from falls have grown by 55%, and death rates grew by 18% since 1990. These trends likely reflect the increasing mean age of the global population.
Geographic and Demographic Distribution of Injury Burden
Most injury deaths occur among young adults. In contrast, global injury related disability is greatest in middle age ( Fig. 2-4, A ), while the rate of injury related disability is greatest in the elderly ( Fig. 2-4, B ). Injuries are much more common among men than women, with the notable exception of fire deaths. In 2010, the overall injury death rate and the injury health burden (i.e., DALYs lost) among men were over twice that among women. Road traffic crashes are the leading cause of injury death and disability up to the age range of 40 to 44 years. Among older adults, falls emerge as the leading cause of injury deaths and disability.
