Major Findings of the 2001 GBD Study
This section, and tables 1.1 and 1.2 , summarize the principle findings of the 2001 GBD study. More detailed findings are reported in chapters 3 and 4 .
[Table .]
[Table .]
Global and Regional Mortality
Slightly more than 56 million people died in 2001, 10.5 million (or nearly 20 percent) of whom were children younger than five years of age. Almost 4 million children died before 1 month of age, with an additional 3.3 million stillbirths (see chapter 6 ). Of these child deaths, 99 percent occurred in low- and middle-income countries. Low- and middle-income countries also account for a comparatively large number of deaths at young and middle adult ages: 30 percent of all deaths occur at ages 15 to 59, compared with 15 percent in high-income countries. The causes of death at these ages, as well as in childhood, are thus important for assessing public health priorities.
Worldwide, one death in every three is from what the GBD study terms Group I causes (communicable diseases, maternal and perinatal conditions, and nutritional deficiencies) (see table 1.1 ). This proportion remains almost unchanged from 1990, with one major difference. Whereas HIV/AIDS accounted for only 2 percent of Group I deaths in 1990, it accounted for 14 percent in 2001. Excluding HIV/AIDS, Group I deaths fell from one-third of total deaths in 1990 to less than one-fifth in 2001. Virtually all Group I deaths are in low- and middle-income countries.
In low- and middle-countries, Group II causes (noncommunicable diseases) are now responsible for more than 50 percent of deaths in adults ages 15 to 59 in all regions except South Asia and Sub-Saharan Africa, where Group I causes, including HIV/AIDS, remain responsible for one-third and two-thirds of deaths, respectively. Outside these two regions, developing countries are now facing a triple burden of disease from communicable diseases, noncommunicable diseases, and injuries (Group III causes). Among low- and middle-income countries as a group, the three leading causes of death in 2001 included ischemic heart disease and cerebrovascular disease, which together accounted for almost one-fifth of all deaths. In other words, the epidemiological transition from infectious to chronic noncommunicable diseases in this group of countries is already well established and is of major relevance to health planning.
Leading Causes of Disability
The 1990 GBD study brought the previously largely ignored burden of nonfatal illnesses, particularly neuropsychiatric disorders, to the attention of health policy makers. The findings of the 2001 GBD study, based on updated data and analyses, confirm that disability and states of less than full health caused by diseases and injuries play a central role in determining the overall health status of populations in all regions of the world. Neuropsychiatric conditions, vision disorders, hearing loss, and alcohol use disorders dominate the overall burden of nonfatal disabling conditions.
In all regions, neuropsychiatric conditions are the most important causes of disability, accounting for more than 37 percent of YLD among adults aged 15 years and older worldwide. The disabling burden of neuropsychiatric conditions is almost the same for males and females, but the major contributing causes are different. While depression is the leading cause of disability for both males and females, the burden of depression is 50 percent higher for females than males, and females also have higher burdens from anxiety disorders, migraine, and senile dementia. In contrast, the male burden for alcohol and drug use disorders is nearly six times higher than that for females and accounts for a quarter of the male neuropsychiatric burden.
More than 85 percent of disease burden from nonfatal health outcomes occurs in low- and middle-income countries, and South Asia and Sub-Saharan Africa account for 40 percent of all YLD. Even though the prevalence of disabling conditions such as dementia and musculoskeletal disease is higher in countries with long life expectancies, this is offset by lower contributions to disability from conditions such as cardiovascular disease, chronic respiratory diseases, and long-term sequelae of communicable diseases and nutritional deficiencies. In other words, people living in developing countries not only face shorter life expectancies than those in developed countries, but also live a higher proportion of their lives in poor health.
Burden of Disease and Injuries
The results of the 2001 GBD study reinforce some of the conclusions of the 1990 GBD study about the importance of including nonfatal outcomes in a comprehensive assessment of global population health. They also confirm the growing importance of noncommunicable diseases in low- and middle-income countries and highlight important changes in population health in some regions since 1990.
HIV/AIDS is now the fourth leading cause of the burden of disease globally and the leading cause in Sub-Saharan Africa, where it is followed by malaria in second place. Seven other Group I causes also appear in the top 10 causes for this region. The epidemiological transition in low- and middle-income countries has resulted in a 20 percent reduction in the per capita disease burden due to Group I causes since 1990. Without the HIV/AIDS epidemic and the associated lack of decline in the burden of tuberculosis, this reduction would have been closer to 30 percent.
The per capita disease burden in Europe and Central Asia has increased by nearly 40 percent since 1990, and population health in this region is now worse than all other regions except South Asia and Sub-Saharan Africa. This reflects the sharp increase in adult male mortality and disability in the 1990s, leading to the highest male-female differential in the disease burden in the world. A significant factor in this increase is probably the high level of harmful alcohol consumption among men, which has led to high rates of accidents, violence, and cardiovascular disease. From 1991 to 1994, the risk of premature adult (15 to 59 years) death increased by 50 percent for Russian males. It improved somewhat between 1994 and 1998, but subsequently increased.
The burden of noncommunicable diseases is increasing, accounting for nearly half the total global burden of disease, a 10 percent increase from estimated levels in 1990. Almost 50 percent of the adult disease burden in low- and middle income countries is now attributable to noncommunicable diseases. The implementation of effective interventions for Group I diseases, coupled with population aging and the spread of risks for noncommunicable disease in many low-and middle-income countries, are the likely causes of this shift. Ischemic heart disease and stroke dominate the burden of disease in Europe and Central Asia and together account for more than a quarter of the total disease burden. In contrast, in Latin America and the Caribbean these diseases account for 8 percent of the disease burden, but this region also has high levels of diabetes and endocrine disorders compared with other regions. Violence is the fourth leading cause of the disease and injury burden in Latin America and the Caribbean. Violence does not appear among the top 10 causes of burden in any other region, but is nonetheless significant.
Injuries primarily affect young adults and often result in severe, disabling sequelae. All forms of injury accounted for 16 percent of the adult burden in 2001.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 aged 15 to 44 is attributable to injuries. Road traffic accidents, violence, and self-inflicted injuries are all among the top 10 leading causes of burden in these regions. The former Soviet Union and other high-mortality (among adults) countries of Eastern Europe have rates of injury death and disability among males that are similar to those in Sub-Saharan Africa.
Burden of Disease Attributable to Risk Factors
As described earlier, a major advance of the 2001 GBD study has been in creating a unified framework for quantifying the burden of disease and injury attributable to major risk factors and in applying this framework to exposure and hazard data for selected major risk factors based on comprehensive and systematic reviews of published literature and other sources. Notwithstanding the inherent uncertainties in assessing the population-level health effects of risk factors, the quantification of the burden of disease attributable to the individual and joint hazards of selected risks suggests that the leading causes of mortality and disease burden include risk factors for Group I conditions (for example, undernutrition; indoor smoke from household use of solid fuels; poor water, sanitation, and hygiene; and unsafe sex), whose burden is primarily concentrated in South Asia and Sub-Saharan Africa, and risk factors for Group II conditions (especially, smoking, alcohol, high blood pressure and cholesterol, and overweight and obesity), which are widespread globally (see table 1.2 ). In low- and middle-income countries, the leading causes of disease burden included risk factors prevalent among the poor and associated with Group I conditions (for example, childhood underweight [8.7 percent of the disease burden in these regions]; unsafe water, sanitation, and hygiene [3.7 percent]; and indoor smoke from household use of solid fuels [3.0 percent]), unsafe sex (5.8 percent), and risk factors for noncommunicable diseases (for example, high blood pressure [5.6 percent], smoking [3.9 percent], and alcohol use [3.6 percent]). Across high-income countries, risk factors associated with Group II and Group III conditions were the leading causes of loss of healthy life (smoking [12.7 percent], high blood pressure [9.3 percent], overweight and obesity [7.2 percent], high cholesterol [6.3 percent], and alcohol use [4.4 percent]).
An estimated 45 percent of global mortality and 36 percent of the global burden of disease were attributable to the joint hazards of the 19 selected global risk factors. The joint hazards were even larger in regions where a relatively small number of diseases and their risk factors were responsible for large losses of life (HIV/AIDS and risk factors for child mortality in Sub-Saharan Africa; cardiovascular risks, including smoking and alcohol use in Europe and Central Asia). Globally, large fractions of major diseases such as diarrhea, lower respiratory infections, HIV/AIDS, lung cancer, chronic obstructive pulmonary disease, ischemic heart disease, and stroke were attributable to the joint effects of the risk factors considered in this volume. The joint hazards of these 19 risks for a number of other important diseases and injuries, such as perinatal and maternal conditions, selected other cancers, and intentional and unintentional injuries, which have more diverse risk factors, were smaller, but nonnegligible. The relatively small number of risk factors that account for a large fraction of the disease burden underscores the need for policies, programs, and scientific research to take advantage of interventions for multiple major risks to health ( Ezzati and others 2003 ).
