Global Burden of Disease in 2001
This section provides an overview of the global and regional burden of disease in 2001 as measured in DALYs, more specifically, in DALYs(3,0). As defined earlier, DALYs(3,0) do not apply nonuniform age weights, but incorporate a 3 percent discount rate and should be distinguished from the DALYs(3,1) used in the GBD results reported by WHO in recent world health reports. In 2001, the global average burden of disease across all regions was 250 DALYs(3,0) per 1,000 population, of which almost two-thirds were due to premature death.
YLL varied dramatically across regions, with YLL rates nearly five times higher in Sub-Saharan Africa than in high-income countries (
figure 3.11
). In contrast, YLD rates were less varied, with Sub-Saharan Africa having 50 percent higher rates than high-income countries. South Asia and Sub-Saharan Africa together bore 45 percent of the total GBD in 2001, even though they account for only one-third of the world's population. East Asia and the Pacific is the "healthiest" of the low- and middle-income regions, with countries such as China now having life expectancies similar to those of many Latin American countries and higher than those in some European countries (see
chapter 2
).
[Figure
3.11]
Europe and Central Asia now experiences a higher burden of disease than all other low- and middle-income regions except South Asia and Sub-Saharan Africa. This reflects the sharp increase in adult male mortality and disability in the 1990s. A significant factor in this increase was the high incidence of male alcohol abuse, which led to high rates of accidents, violence, and CVD. From 1991 to 1994, the risk of premature death increased by 50 percent for Russian males ( Gavrilova and others 2000 ; Semenova and others 2000 ; Shkolnikov, McKee, and Leon 2001 ). Between 1994 and 1998, life expectancy for males improved, but declined again significantly between 1998 and 2001 ( Men and others 2003 ).
While countries in Europe and Central Asia have a substantially higher burden of noncommunicable disease than high-income countries (
figure 3.12
), they also have a higher burden due to Group I causes and Group III causes. Indeed, countries in Europe and Central Asia have the highest proportion of the burden due to injuries of all the regions, 14 percent, followed by the Middle East and North Africa.
[Figure
3.12]
Leading Causes of the Burden of Disease in 2001
The 20 leading causes of burden of disease for both sexes together are shown in table 3.14 .While the two leading causes of death, IHD and cerebrovascular disease, remain among the top four causes of the burden of disease, four nonfatal conditions are also among the top 20 causes of burden: unipolar depressive disorders, adult-onset hearing loss, cataracts, and osteoarthritis. This once again illustrates the importance of taking nonfatal conditions into account, as well as deaths, when assessing the causes of loss of health in populations.
[Table .]
In 2001, the leading causes of the burden of disease in low- and middle-income countries were broadly similar to those for the world as a whole ( table 3.15 ), and included six Group I causes among the top 10, but the leading causes in high- income countries consisted entirely of Group II conditions, including three (unipolar depressive disorders, adult-onset hearing loss, and alcohol use disorders) for which direct mortality is low.
[Table .]
Age and Sex Differences in the Burden of Disease
Measured in DALYs(3,0), children younger than 15 accounted for 36 percent of the world's total burden of disease and injury in 2001 and adults ages 15 to 59 accounted for almost 50 percent. Low- and middle-income countries accounted for the vast majority of the disease burden for children (
figure 3.13
). While the proportion of the total burden of disease borne by adults ages 15 to 59 was the same in both groups of countries, adults older than 60 accounted for a significantly larger share of the disease burden in high-income countries.
[Figure
3.13]
Although injuries become more important for boys beyond infancy, the causes of the burden of disease are broadly similar for boys and girls. However, striking gender differences emerge in adulthood. In low- and middle-income countries, 5 of the 10 leading causes of DALYs(3,0) for men ages 15 to 44 are injuries. Indeed, after HIV/AIDS, road traffic accidents were the second leading cause of the burden of disease for men in this age group. Other unintentional injuries and violence were the third and fourth leading causes, with self-inflicted injuries and war also appearing in the top 10 causes. Injuries were also important for women ages 15 to 44, although road traffic accidents were the 10th leading cause, preceded by other unintentional injuries in 4th place and self-inflicted injuries in 6th place. Unipolar depressive disorders were the second leading cause of the burden for women in this age group, after HIV/AIDS.
The Growing Burden of Noncommunicable Diseases
The burden of noncommunicable diseases is increasing, accounting for nearly half the global burden of disease for all ages, a 10 percent increase from estimated levels in 1990. While the proportion of the burden from noncommunicable disease in high-income countries has remained stable at around 85 percent in adults ages 15 and older, the proportion in middle-income countries has already exceeded 70 percent. Surprisingly, almost 50 percent of the adult disease burden in low- and middle-income countries is now attributable to noncommunicable disease. Population aging and changes in the distribution of risk factors have accelerated the epidemic of noncommunicable disease in many developing countries.
CVD accounted for 13 percent of the disease burden among adults ages 15 and older in 2001. IHD and cerebrovascular disease (stroke) were the two leading causes of mortality and the disease burden among adults ages 60 and older and were also among the top 10 causes of the disease burden in adults ages 15 to 59. In low- and middle income countries, IHD and cerebrovascular disease (stroke) were together responsible for 15 percent of the disease burden in those ages 15 and older, and DALYs(3,0) rates were higher for men than for women.
The proportion of the burden among adults ages 15 and older attributable to cancer was 6 percent in low- and middle income countries and 14 percent in high-income countries in 2001. Of the 7.1 million cancer deaths estimated to have occurred in that year, 17 percent, or 1.2 million, were attributable to lung cancer alone, and of these, three-quarters occurred among men. The number of cases of lung cancer increased nearly 30 percent since 1990, largely reflecting the emergence of the tobacco epidemic in low- and middle-income countries.
Stomach cancer, which until recently was the leading site of cancer mortality worldwide, has been declining in all parts of the world where trends can be reliably assessed, and in 2001 caused 842,000 deaths, or about two-thirds as many as lung cancer. Liver cancer was the third leading site, with 607,000 deaths in 2001, more than 60 percent of them in the East Asia and Pacific region. Among women, the leading cause of cancer deaths was breast cancer. Breast cancer survival rates have been improving during the past decade, but the chance of survival varies according to the coverage of and access to secondary prevention. Globally, neuropsychiatric conditions accounted for 19 percent of the disease burden among adults, primarily from nonfatal health outcomes.
Injuries: The Hidden Epidemic
Injuries, both unintentional and intentional, primarily affect young adults, and often result in severe, disabling sequelae. In 2001, injuries accounted for 16 percent of the adult burden of ill-health and premature death worldwide. In parts of Europe and Central Asia, Latin America and the Caribbean, and the Middle East and North Africa, more than 30 percent of the entire disease and injury burden among male adults ages 15 to 44 was attributable to injuries, and road traffic accidents, violence, and self-inflicted injuries were all among the top 10 leading causes of the burden of disease. Globally, road traffic accidents were the third leading cause of burden in the same age and sex group, preceded only by HIV/AIDS and unipolar depression. The burden of road traffic accidents has been increasing, especially in the developing countries of Sub-Saharan Africa and South and Southeast Asia, and particularly affects males.
Intentional injuries, which include self-inflicted injuries and suicide, violence, and war, accounted for an increasing share of the burden, especially among economically productive young adults. In developed countries, suicides accounted for the largest share of the intentional injury burden, whereas in developing regions, violence and war were the major sources. The former Soviet Union and other high-mortality countries of Eastern Europe have rates of death and disability resulting from injury among males that are similar to those in Sub-Saharan Africa.
Regional Variations in the Burden of Disease
The tables in annex 3C show estimated total DALYs(3,0) by age, sex, and cause in 2001 for each region and for the world as a whole. Table 3.16 summarizes the 10 leading causes of burden for each of the low- and middle-income regions.
[Table .]
In 2001, IHD and stroke dominated the burden of disease in Europe and Central Asia, and together accounted for more than a quarter of the total disease burden. In contrast, in Latin America and the Caribbean, these diseases accounted for 8 percent of disease burden. However, this region also had high levels of diabetes and endocrine disorders compared with other regions. Violence was the third leading cause of burden in Latin America and Caribbean countries, but did not reach the top 10 in any other region.
HIV/AIDS was the leading cause of the burden of disease in Sub-Saharan Africa, followed by malaria. Seven other Group I causes also appear in the top 10 causes for this region, with road traffic accidents being the only non-Group I cause.
Group I, II, and III causes all appear among the top 10 causes of the disease burden for the Middle East and North Africa. Of particular note, road traffic accidents were the third leading cause and congenital anomalies were the seventh leading cause.
Group I causes of the disease burden remained dominant in South Asia, and this burden fell particularly on children, but noncommunicable diseases such as IHD, stroke, and chronic obstructive pulmonary disease also featured in the list of top 10 causes.
In East Asia and the Pacific, stroke was the leading cause of disease burden in 2001, with IHD in fourth place, although Group I causes such as conditions arising during the perinatal period, TB, lower respiratory infections, and diarrheal diseases remained important.
