Chapter 1: Global Health: today's challenges
Adult health at risk: slowing gains and widening gaps
Adult mortality rates have been declining in recent decades in most regions of the world. Life expectancy at age 15 has increased by between 2 and 3 years for most regions over the last 20 years. The notable exceptions are the high-mortality countries in Africa, where life expectancy at age 15 decreased by nearly 7 years between 1980 and 2002, and the high-mortality countries, mainly those of the former Soviet Union, in eastern Europe, where life expectancy at age 15 decreased over the same period by 4.2 years for males and 1.6 years for females.
Of the 45 million deaths among adults aged 15 years and over in 2002, 32 million, or almost three-quarters, were caused by noncommunicable diseases, which killed almost four times as many people as communicable diseases and maternal, perinatal and nutritional conditions combined (8.2 million, or 18% of all causes). Injuries killed a further 4.5 million adults in 2002, 1 in 10 of the total adult deaths. More than 3 million of these injury deaths -- almost 70% of them -- concern males, whose higher risk is most pronounced for road traffic injuries (three times higher) and for violence and war (more than four times higher).
The relative importance of these causes varies markedly across regions. Thus in Africa, only about 1 in 3 adult deaths is caused by noncommunicable diseases, compared with nearly 9 out of 10 in developed countries. It is of concern that 3 in 4 adult deaths in Latin America and in the developing countries of Asia and the Western Pacific Region are caused by noncommunicable disease, reflecting the relatively advanced stage of the epidemiological transition achieved in these populations and the emergence of the double burden of disease. Estimated total deaths by cause in 2002 are given for each of the epidemiological subregions and the world in Annex Table 2. More detailed tables showing deaths by cause, age and sex in each of the regions are available on the WHO web site (http://www.who.int/evidence/bod).
Figure 1.8 highlights the marked contrast in patterns of health transition among adults (aged 15 years and over) in different parts of the world. In developed countries, communicable diseases and maternal, perinatal and nutritional conditions contribute only 5% to the total burden of disease, while in high-mortality developing regions this figure rises to 40%. In African regions where the HIV/AIDS epidemic has confounded the pattern of health transition during the past decade, these conditions can contribute as much as 50--60% of the overall disease burden. Estimated total DALYs by cause in 2002 are given for each of the epidemiological subregions and the world in Annex Table 3.
The 10 leading causes of disease burden among men and women aged 15 years and over are shown in Table 1.2. Ischaemic heart disease and stroke (cerebrovascular disease) are two of the three leading causes of burden of disease in adult males globally. HIV/AIDS is the leading cause for males and the second leading cause for females, accounting for around 6% of the global burden of disease. Unipolar depressive disorders are the leading cause of burden for females, reflecting their higher prevalence in women. Though the individual maternal conditions of haemorrhage, sepsis and obstructed labour do not appear in Table 1.2, as a group they remain one of the leading causes of the burden of disease for women globally, reflecting the continuing high levels of maternal mortality in many developing countries, and also the high levels of disability resulting from these conditions.
The following section summarizes the risk of premature adult death in terms of the probability of death between 15 and 60 years of age -- the proportion of 15-year-olds who will die before their 60th birthday -- and examines global patterns of cause of death in the age range 15--59 years. The health of adults aged 60 years and older is then examined.
Global patterns of premature mortality risk
The probability of premature adult death varies widely between regions, as shown in Figure 1.9. For example, the probability of premature adult death in some parts of sub-Saharan Africa is much higher -- nearly four times higher -- than that observed in low-mortality countries of the Western Pacific Region. Even within developed regions there are wide variations. Men in some eastern European countries are three to four times more likely to die prematurely than men in other developed regions. Furthermore, male adult mortality in eastern Europe is much greater than in developing countries of the Americas, Asia and the Eastern Mediterranean Region. In all regions, male mortality is higher than female, and the discrepancy between the two sexes in mortality risk is much larger than that seen among children. The variation in the proportion of women dying prematurely is much less dramatic.
Adult mortality trends: 15--59 years of age
There have been impressive gains in the health status of adults worldwide in the past five decades. The risk of death between ages 15 and 60 has declined substantially from a global average of 354 per 1000 in 1955 to 207 per 1000 in 2002. The recent slowdown in the rate of decline is a clear warning that continued reductions in adult mortality, particularly in developing countries, will not be easily achieved.
There is substantial variation in the pace and magnitude of declining trends in premature adult mortality across both sexes and global regions (see Figure 1.10). The global slowdown of the pace is primarily a result of a shift in trends in adult mortality in a few regions. Among the signs of deteriorating adult health, the most disturbing is the fact that adult mortality in Africa has reversed, shifting in 1990 from a state of steady decline into a situation characterized by rapidly increasing mortality. The reversal in parts of sub-Saharan Africa has been so drastic that current adult mortality rates today exceed the levels of three decades ago. In Zimbabwe, upturns in reported adult deaths were significantly greater in 1991--1995 than in 1986--1990. Older childhood and older adult mortality have changed little (9). Without HIV/AIDS, life expectancy at birth in the African Region would have been almost 6.1 years higher in 2002. The reduction in life expectancy varies significantly across the African Region. The greatest impact has been in Botswana, Lesotho, Swaziland and Zimbabwe, where HIV/AIDS has reduced male and female life expectancies by more than 20 years.
The fragile state of adult health in the face of social, economic and political instability is also apparent in regions outside Africa. Male mortality in some countries in eastern Europe has increased substantially and is approaching the level of adult mortality in some African countries. As a result, for the European Region as a whole, average adult mortality risk for men between 15 and 60 years is 230 per 1000, which is similar to the rate observed in the 1980s. This contrasts with the continuously declining trend for women in this region as a whole. Their risk has declined from 130 in 1970 to 98 in 2002. Figure 1.8 illustrates the fact that the probability of death from injury among adults aged 15--59 years in the high-mortality countries of eastern Europe is nearly six times higher than in neighbouring western European countries.
Adult mortality: widening gaps
Continuously declining adult mortality in low-mortality regions, combined with trend reversals in high-mortality areas, have resulted in widening gaps in adult mortality worldwide. The gap between the lowest and highest regional adult mortality risk between ages 15 and 60 has now increased to a level of 340 per 1000 in 2002. Regional aggregation of adult mortality also hides enormous and sobering disparities between countries. For example, within the Eastern Mediterranean Region, adult mortality risk between ages 15 and 60 among women in Djibouti was seven times higher than that of women in Kuwait in 2002. Overall, there is an almost 12-fold difference between the world's lowest and highest adult mortality at country level (see Annex Table 1).
HIV/AIDS: the leading health threat
Table 1.3 shows the leading causes of deaths and DALYs among adults worldwide for 2002. Despite global trends of declining communicable disease burden in adults, HIV/AIDS has become the leading cause of mortality and the single most important contributor to the burden of disease among adults aged 15--59 years (see Chapter 3).
Nearly 80% of the almost 3 million global deaths from HIV/AIDS in 2002 occurred in sub-Saharan Africa. As stated earlier, HIV/AIDS is the leading cause of death in this region. It causes more than 6000 deaths every day and accounts for one in two deaths of adults aged 15--59 years. It has reversed mortality trends among adults in this region and turned previous gains in life expectancy into a continuous decline in life expectancy since 1990.
Mortality and disease among older adults
In developing countries, 42% of adult deaths occur after 60 years of age, compared with 78% in developed countries. Globally, 60-year-olds have a 55% chance of dying before their 80th birthday. Regional variations in risk of death at older ages are smaller, ranging from around 40% in the developed countries of western Europe to 60% in most developing regions and 70% in Africa. Historical data from countries such as Australia and Sweden show that life expectancy at age 60 changed slowly during the first six to seven decades of the 20th century but, since around 1970, has started to increase substantially. Life expectancy at age 60 has now reached 25 years in Japan. From 1990 onwards, eastern European countries such as Hungary and Poland have started to experience similar improvements in mortality for older people, but others, such as the Russian Federation, have not, and are experiencing worsening trends. The leading causes of mortality and burden of disease in older people have not changed greatly over the past decade.
The growing burden of noncommunicable diseases
The burden of noncommunicable diseases is increasing, accounting for nearly half of the global burden of disease (all ages), a 10% increase from estimated levels in 1990. While the proportion of burden from noncommunicable diseases in developed countries remains stable at over 80% in adults aged 15 years and over, the proportion in middle-income countries has already exceeded 70%. Surprisingly, almost 50% of the adult disease burden in the high-mortality regions of the world is now attributable to noncommunicable diseases. Population ageing (see Box 1.3) and changes in the distribution of risk factors have accelerated the epidemic of noncommunicable diseases in many developing countries (10).
Box 1.3 Population ageing
A demographic revolution is under way throughout the world. Today, there are around 600 million people in the world aged 60 years and over. This total will double by 2025 and by 2050 will reach two billion, the vast majority of whom will be in the developing world. Such accelerated global population ageing will increase economic and social demands on all countries.
While the consequences of population ageing in the areas of health and income security are already at the centre of discussions by policy-makers and planners in the developed world, the speed and impact of population ageing in the less developed regions are yet to be fully appreciated. By 2025, in countries such as Brazil, China and Thailand, the proportion of older people will be above 15% of the population, while in Colombia, Indonesia and Kenya the absolute numbers will increase by up to 400% over the next 25 years -- up to eight times higher than the increases in already aged societies in western Europe where population ageing occurred over a much longer period of time (11).
Population ageing is driven by two factors: a decline in the proportion of children, reflecting declines in fertility rates in the overall population, and an increase in the proportion of adults 60 years of age and over as mortality rates decline. This demographic transition will bring with it a number of major challenges for health and social policy planners. As populations age, the burden of noncommunicable diseases increases. Evidence from developed countries, however, shows that the prevalence of chronic diseases and the levels of disability in older people can be reduced with appropriate health promotion and strategies to prevent noncommunicable diseases. It is of great concern that the prevalence of risk factors for chronic diseases is on the increase in developing countries. Opportunities missed by health systems to deal with or manage age-related noncommunicable diseases will lead to increases in the incidence, prevalence and complications of these diseases and may take resources away from other priorities, such as child and maternal health.
Improving health systems and their responses to population ageing makes economic sense. With old-age dependency ratios increasing in virtually all countries of the world, the economic contributions and productive roles of older people will assume greater importance. Supporting people to remain healthy and ensure a good quality of life in their later years is one of the greatest challenges for the health sector in both developed and developing countries (12).
Cardiovascular diseases account for 13% of the disease burden among adults over 15 years of age. Ischaemic heart disease and cerebrovascular disease (stroke) are the two leading causes of mortality and disease burden among older adults (over age 60). In developed countries, ischaemic heart disease and cerebrovascular disease are together responsible for 36% of deaths, and death rates are higher for men than women. The increase in cardiovascular mortality in eastern European countries has been offset by continuing declines in many other developed countries. In contrast, the mortality and burden resulting from cardiovascular diseases are rapidly increasing in developing regions (see Chapter 6).
Of the 7.1 million cancer deaths estimated to have occurred in 2002, 17% were attributable to lung cancer alone and of these, three-quarters occurred among men (13). There were an estimated 1.2 million lung cancer deaths in 2000, an increase of nearly 30% in the 10 years from 1990, reflecting the emergence of the tobacco epidemic in low-income and middle-income countries.
Stomach cancer, which until recently was the leading cause of cancer mortality worldwide, has been declining in all parts of the world where trends can be reliably assessed, and now causes 850 000 deaths each year, or about two-thirds as many as lung cancer. Liver and colon/rectum cancers are the third and fourth leading causes. More than half of all liver cancer deaths are estimated to occur in the Western Pacific Region. Among women, the leading cause of cancer deaths is breast cancer. During the past decade, breast cancer survival rates have been improving, though the chance of survival varies according to factors such as coverage and access to secondary prevention. Globally, neuropsychiatric conditions account for 19% of disease burden among adults (see Box 1.4), almost all of this resulting from non-fatal health outcomes.
Box 1.4 The burden of mental ill-health
Mental, neurological and substance use disorders cause a large burden of disease and disability: globally, 13% of overall disability-adjusted life years (DALYs) and 33% of overall years lived with disability (YLDs). Behind these stark figures lies human suffering: more than 150 million people suffer from depression at any point in time; nearly 1 million commit suicide every year; and about 25 million suffer from schizophrenia, 38 million from epilepsy, and more than 90 million from an alcohol or drug use disorder.
A large proportion of individuals do not receive any health care for their condition, firstly because the mental health infrastructure and services in most countries are grossly insufficient for the large and growing needs (14) and, secondly, because widely prevalent stigma and discrimination prevent them from seeking help. A policy for mental health care is lacking in 40% of countries, and 25% of those with a policy assign no budget to implement it. Even where a budget exists, it is very small: 36% of countries devote less than 1% of their total health resources to mental health care. Though community-based services are recognized to be the most effective, 65% of all psychiatric beds are still in mental hospitals -- cutting into the already meagre budgets while providing largely custodial care in an environment that may infringe patients' basic human rights.
Cost-effective health care interventions are available. Recent research clearly demonstrates that disorders such as depression, schizophrenia, alcohol problems and epilepsy can be treated within primary health care. Such treatment is well within the reach of even low-income countries and will reduce substantially the overall burden of these disorders. Interventions rely on inexpensive medicines that are commonly available and, for the most part, free of patent restrictions, and basic training of health professionals (15).
Mental health also has an impact on health care systems in other ways. A large proportion of people with chronic physical diseases such as diabetes and hypertension, malignancies and HIV/AIDS suffer from concurrent depression, which significantly interferes with their adherence to health care regimens. Behavioural and lifestyle factors are also responsible for many communicable and noncommunicable diseases (10). Though these links have been recognized, most countries are not adequately using this information to enhance the effectiveness of their health care systems.
Injuries -- a hidden epidemic among young men
Injuries, both unintentional and intentional, primarily affect young adults, often resulting in severe disabling consequences. Overall, injuries accounted for over 14% of adult disease burden in the world in 2002. In parts of the Americas, eastern Europe and the Eastern Mediterranean Region, more than 30% of the entire disease burden among male adults aged 15--44 years is attributable to injuries.
Among men, road traffic injuries, violence and self-inflicted injuries are all among the top 10 leading causes of disease burden in the 15--44-year-old age group. Globally, road traffic injuries are the third leading cause of burden in that age and sex group, preceded only by HIV/AIDS and unipolar depression. The burden of road traffic injuries is increasing, especially in the developing countries of sub-Saharan Africa and South-East Asia, and particularly affects males (see Chapter 6).
Intentional injuries, a group that includes self-inflicted injuries and suicide, violence and war, account for an increasing share of the burden, especially among economically productive young adults. In developed countries, suicides account for the largest share of intentional injury burden whereas, in developing regions, violence and war are the major causes. Countries of the former Soviet Union and other high-mortality countries of eastern Europe have rates of injury death and disability among males that are similar to those in sub-Saharan Africa.
Non-fatal health outcomes
The overall burden of non-fatal disabling conditions is dominated by a relatively short list of causes. In all regions, neuropsychiatric conditions, largely depression, are the most important causes of disability, accounting for over 35% of YLDs among adults (aged 15 and over). Their disabling burden is almost the same for men and women, but the major contributing causes are different. The burden of depression is 50% higher for women than for men, and women also have higher burden from anxiety disorders, migraine and senile dementias. In contrast, the burden for alcohol and drug use disorders is nearly six times higher in men than in women, and accounts for one-quarter of the male neuropsychiatric burden.
In high-mortality developing regions, visual impairment, hearing loss and HIV/AIDS are the other major contributors to YLDs. In developed and low-mortality developing regions, visual impairment, hearing loss, musculoskeletal disease, chronic obstructive pulmonary disease, and other noncommunicable diseases, particularly stroke, account for the majority of adult disability.1
Surprisingly, more than 80% of global YLDs are in developing countries and nearly half occur in high-mortality developing countries. Figure 1.11 shows higher rates of YLDs per 1000 (age-standardized to the world population in 2002) in developing regions, indicating a higher incidence of disabling conditions as well as increased levels of severity of these conditions. Although the prevalence of disabling conditions, such as dementia and musculoskeletal disease, is higher in countries with long life expectancies, this is offset by lower 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 lower life expectancies (higher risk of premature death) than those in developed countries, but also live a higher proportion of their lives in poor health.
Healthy life expectancy varies across regions of the world even more than total life expectancy, ranging from a low of 41 years for sub-Saharan Africa to 71.4 years for western Europe, with a global average of 57.7 years in 2002. Healthy life expectancy converts total life expectancy into equivalent years of "full health" by taking into account years lived in less than full health as a result of diseases and injuries. The gap between total life expectancy and healthy life expectancy represents the equivalent lost healthy years resulting from states of less than full health in the population, and ranges from 9% in the European Region and the Western Pacific Region to 15% in Africa. Annex Table 4 contains estimates of healthy life expectancy for all WHO Member States in 2002.
To sum up, this chapter is a reminder that children are among the most vulnerable members of societies around the world. Despite considerable achievements, much still needs to be done, urgently, to avert child deaths from preventable causes. The success stories in many poor countries in all regions demonstrate clearly that much progress can be made with limited resources. Tragically, many other countries, particularly in Africa, have lost the ground gained in previous decades. The gaps in mortality between rich and poor populations are widening, leaving 7% of the world's children and 35% of Africa's children at higher risk of death today than they were 10 years ago.
In the last five decades there have been impressive gains in adult health status worldwide. The average figures, however, mask disparities in population health. Of great concern are the reversals in adult mortality in the 1990s in sub-Saharan Africa caused by HIV/AIDS and in parts of eastern Europe attributable to a number of noncommunicable diseases (particularly cardiovascular and alcohol-related diseases) and injuries.
Demographic trends and health transitions, along with changes in the distribution of risk factors, have accelerated the epidemic of noncommunicable disease in many developing countries. Infectious diseases such as HIV/AIDS and tuberculosis have serious socioeconomic consequences in both the developed and the developing worlds. Thus, the majority of developing countries are facing a double burden from both communicable and noncommunicable diseases. In addition, contrary to common perceptions, disabilities tend to be more prevalent in developing regions, as the disease burden is often skewed towards highly vulnerable sub-populations. The global public health community is now faced with a more complex and diverse pattern of adult disease than previously expected. It has been estimated that 47% of premature deaths and 39% of the total disease burden result from 20 leading risk factors for childhood and adult diseases and injuries and that removal of these risks would increase global healthy life expectancy by 9.3 years, ranging from 4.4 years in industrialized countries of the Western Pacific Region to 16.1 years in parts of sub-Saharan Africa (16).
Historically unprecedented increases in life expectancy at older ages in developed countries have already exceeded earlier predictions of maximum population life expectancy. With such increases, the non-fatal burden of disease plays an increasingly important role, and it will be a major goal of health policy worldwide to ensure that longer life is accompanied by greater health and less disability.
This chapter has described many of the facts of life and death across the world and the underlying trends that influence them. Much of what has been reviewed here relates closely to the health-related Millennium Development Goals. Understanding the goals, and why the progress towards them is so important and at the same time so difficult, is the subject of the next chapter.