Mortality: Global patterns and trends

Transcription

1 Mortality: Global patterns and trends Although global mortality variations have declined significantly in the last century, considerable inequalities remain, reflecting at least partly the wealth gap between MEDCs (more economically developed countries) and LEDCs (less economically developed countries). However, mortality differences exist not only on the global scale but also within continents, countries and national regions. This year, almost eleven million children under five years of age will die from causes that are largely preventable. Among them are four million babies who will not survive the first month of life. On top of that 3.3 million babies will be stillborn. At the same time, about half a million women will die in pregnancy, childbirth or soon after. The World Health Report 2005 The global decline in mortality The decline in levels of mortality and the increase in life expectancy has been the most tangible reward of development. On a global scale, 75 per cent of the total improvement in longevity has been achieved in the twentieth century and the early years of the twenty-first century. In 1900, the world average for life expectancy is estimated to have been about 30 years, but by it had risen to 46 years. By it had reached a fraction under 60 years and is presently, according to the 2005 World Population Data Sheet (Population Reference Bureau), 67 years. However, the global average masks significant differences by world region. The twentieth century s fall in mortality was particularly marked from after the Second World War, which had provided a tremendous impetus for research into tropical diseases. It is thus not surprising that the pace of mortality reduction was especially rapid in the 1950s and 1960s. Mortality reduction slowed in the 1970s, as large-scale programmes for the eradication of diseases reached their limits. From then on, the most obvious aspects of poverty poor nutrition and lack of clean water and sanitation have slowed improvement in much of the developing world. How is mortality measured? The crude death rate, the most common measure of mortality, is also the most limited in scope. The term crude in terms of statistical data means that the data (here, the crude death rate) is very generalised because it has not been analysed in detail. The crude death rate looks at the mortality of the whole population, so it is heavily influenced by age structure. For example, Brazil (7 per 1000) has a lower crude death rate than Britain (10 per 1000) because it has a much younger population. In Brazil, 29 per cent of the population are under 15 years of age, with only 6 per cent at 65 years and over. For Britain the respective figures are 18 per cent and 16 per cent. However, as most people would expect, life expectancy is considerably higher in Britain at 78 years compared with 71 years in Brazil. This is because living standards are much better in Britain, mainly as a result of significantly higher incomes. Therefore the most accurate measures of mortality are: life expectancy age-specific mortality rates. In terms of the latter, the infant mortality rate, with a one-year age band, is the most frequently used, followed by the child mortality rate life expectancy with a five-year age band. The infant mortality rate is often seen as the best measure of a country s socio-economic progress because investing in health, water supply and other basic aspects of development can significantly reduce infant mortality. More detailed analyses of mortality also consider the perinatal and neonatal mortality rates. Mortality rates are available at every year of age in many countries, particularly the more affluent ones where records are extremely accurate because of the legal requirement to register all deaths. Age-specific mortality data is used by the life insurance industry to set premiums. All other things being equal, insurance premiums increase with age.

2 The crude death rate: global variations From what has already been said about the influence of age structure, it is not surprising that the lowest crude death rates are in the developing world (Figure 1). For each country listed in Figure 1 the percentage of population under 15 and 65-plus also illustrates the impact of age structure on the crude death rate. Figure 1. Lowest crude death rates. The 2005 Population Data Sheet recorded a crude death rate of only 1/1000 for the United Arab Emirates and 2/1000 for Kuwait. Bahrain, Qatar, Saudi Arabia, Andorra and Brunei have a rate of 3/1000. Apart from Andorra, all these countries have at least 25 per cent of their populations under the age of 15. And again, apart from Andorra, all of these countries have no more than 3 per cent of their populations aged 65 and over. However, some of the highest crude death rates are also in the developing world, concentrated in the poverty belt of sub-saharan Africa (Figure 2), with Botswana and Lesotho recording the highest figure of 28 per Even the impact of very high fertility cannot mask high age-specific mortality, resulting in an average life expectancy in Africa as a whole of 52 years, well below any other world region. Figure 2. Highest crude death rates.

3 Mortality rates can of course also vary significantly within individual countries. This holds true for both developed and developing countries. Regions benefiting from a higher level of medical infrastructure and a better quality of life will generally control mortality to a greater extent than worse-off regions. Figure 3. Rural Morocco, where health facilities are much less advanced than in the main urban areas. Infant mortality As has already been mentioned, the infant mortality rate is generally regarded as a prime indicator of socio-economic progress. It is the most sensitive of the age-specific rates. Over the world as a whole, infant mortality has declined sharply during the last half century. In the global average was 138 per 1000, but by it was down to 88 per 1000, and now it is down to 54 per The average for MEDCs stands at 6 per 1000, while the rate in LEDCs is 59 per Although mortality rates have fallen rapidly over recent years in most countries, wide spatial variations remain on the global scale. The highest current rates (Figure 4) are: Angola (187 per 1000) Afghanistan (163) Sierra Leone (162) Liberia (161). A total of twenty countries have rates below 4.70 per 1000, led by Singapore, Sweden, Hong Kong and Japan.

4 Figure 4. Highest infant mortality rates. Maternal mortality About 500,000 women die each year from complications associated with pregnancy and childbirth. In 2000, 95 per cent of maternal deaths occurred in Asia and sub-saharan Africa. Four per cent occurred in Latin America and the Caribbean, with less than 1 per cent in MEDCs. The risk of maternal death is far greater in Africa than anywhere else. An African woman has a 1 in 16 chance of dying in pregnancy or childbirth over her lifetime, compared with 1 in 94 in Asia. In Europe the figure is 1 in 2,400. The main causes of maternal death are excessive bleeding, infections, hypertensive disorders, obstructed labour, or complications from unsafe abortions. The UN estimates that 15 per cent of all pregnancies result in complications. However, predicting which individuals are going to be affected by complications is difficult. This is one of the main reasons why tackling high rates of maternal mortality in poor countries has proved to be so difficult. Life expectancy: global convergence Rates of life expectancy at birth have converged significantly between rich and poor countries over the past 50 years or so in spite of a widening wealth gap (Figure 5). According to a recent article entitled The Quantity and Quality of Life and the Evolution of World Inequality (G.Becker et al, American Economic Review 95, 1, 2005), these increases in life expectancy more than offset the widening disparity between per capita incomes in MEDCs and LEDCs. However, it must not be forgotten that AIDS in particular has caused recent decreases in life expectancy in some countries. According to the World Health Organisation, life expectancy increased by an average of 23 years between 1960 and 2000 in the poorest 50 per cent of countries, but only by 9 years in the richest 50 per cent. East Asia and the Pacific recorded the greatest increase during this period, up from 42 to 71 years. In contrast, the lowest increase was in North America where life expectancy rose from 70 to 77 years. Figure 5 shows current variations in life expectancy by world region, while Figure 6 identifies the individual countries with the highest and lowest life expectancies.

5 Figure 5. Life expectancy at birth in MEDCs and LEDCs. Figure 6. Highest and lowest life expectancy (in years). The contrasting causes of death in MEDCs and LEDCs Causes of death vary significantly between the developed and developing worlds (Figure 7). In the developing world, infectious and parasitic diseases account for over 40 per cent of all deaths. They are also a major cause of disability as well as social and economic upheaval. This is due to a lack of adequate healthcare and sanitation. In contrast, in the developed world these diseases have a relatively low impact. In rich countries heart disease and cancer (diseases associated with lifestyle and stress) are the big killers.

6 Figure 7. Causes of death in MEDCs and LEDCs. In 2002, 75 per cent of all deaths from infectious diseases occurred in southeast Asia and sub-saharan Africa. In fact, over 60 per cent of all deaths in Africa are from infectious diseases (Figure 8). This contrasts with a rate of 5 per cent in Europe. In excess of 90 per cent of global deaths from infectious diseases are due to a relatively small number of diseases (Figure 9). Children and women are particularly susceptible to the impact of infectious diseases. Figure 8. Infectious diseases as a proportion of all deaths, 2001.

7 Figure 9 Deaths due to diseases accounted by each region, Apart from the challenges of the physical environment in many developing countries, a range of social and economic factors contribute to the high rates of infectious diseases. These include: poverty poor access to healthcare antibiotic resistance evolving human migration patterns new infectious agents. When people live in overcrowded and unsanitary conditions, communicable diseases such as tuberculosis and cholera can spread rapidly. Limited access to heathcare and medicines means that otherwise treatable conditions such as malaria and tuberculosis are often fatal to poor people. Poor nutrition and deficient immune systems are also key risk factors for several big killers such as lower respiratory infections, tuberculosis and measles. In recent decades HIV/AIDS has had a devastating impact, particularly in sub-saharan Africa. According to the Global Health Council, Since the early 1990s, the tuberculosis epidemic has been largely driven by the HIV/AIDS pandemic. Fueled by growing antibiotic resistance, inappropriate prescription of ineffective drugs and poor adherence to medication, infectious diseases once believed to be under control have re-emerged as major global threats. Because of their suppressed immune systems, people co-infected with HIV and TB are many times more likely to develop active TB. Road deaths In the twentieth century (the first recorded pedestrian death was in 1896), motor vehicles have claimed over 30 million lives. In 2002, 1.18 million people died around the world as a result of road traffic injuries. In the same year road crashes ranked as the ninth leading cause of burden of disease, accounting for 2.6 per cent of all life years spent in disability around the world. Ninety per cent of global mortality resulting from road crashes occurred in low and middle income countries. Africa has the highest road traffic death

8 rate. Globally, mortality due to road traffic accidents is also almost three times higher for males than females. In most MEDCs vehicle drivers and passengers account for the majority of road traffic deaths. IN LEDCs, deaths occur mostly among pedestrians, motorcyclists, cyclists and users of public transport. Figure 10 Road traffic in Cairo. The economic consequences of road crashes include medical costs, often loss of the main family income and loss of income due to disability, which together often push families into poverty in many LEDCs. These costs typically amount to between 1 and 2.5 per cent of a country s gross national product (GNP). The Federation of Red Cross and Red Crescent Societies calculate that road accidents cost developing countries about 32 billion a year, almost as much as all the aid they receive. The World Health Organisation estimates that by 2020 road traffic injuries could rank third in the order of burden of disease, ahead of other health problems such as malaria, tuberculosis, and even HIV/AIDS. Inequalities within Britain Life expectancy in Britain has increased dramatically in the last century. The average national figure now stands at 78 years, with 81 years for females and 76 years for males. This contrasts with a life expectancy of 49 years for women and 45 years for men in Life expectancies for Britain are calculated annually by the Government Actuary s Department (GAD). However, even in a rich country such as Britain there are large regional differences. Eight out of the ten local authority areas in Britain with the lowest male life expectancy at birth ( ) are in Scotland (Figure 11). The lowest male life expectancy of 69.1 years is in Glasgow City. The highest male life expectancy of 80.1 years is in East Dorset. The highest female life expectancy of 84.8 years is in Kensington and Chelsea. The lowest female life expectancy of 76.4 years is in Glasgow City. Glasgow City is the only area in Britain where male life expectancy is less than 70 years. The gap between Glasgow City and East Dorset for male life expectancy is 11 years. For the areas with the highest and lowest female life expectancy (Glasgow City and Kensington and Chelsea) the gap is eight and a half years.

9 Figure 11. Life expectancy in the Britain (in years). Although people are living longer than they were 20 years ago, the extra years have not necessarily been lived in good health. Life expectancy in Britain has increased faster than healthy life expectancy. The difference between life expectancy and healthy life expectancy is the number of years a person can expect to live on poor health. In 2001, this was 8.7 years for males and 11.6 years for females. The time gap in healthy life expectancy between the sexes is smaller than for total life expectancy. Death rates increase with age from 8 per 1000 men aged to 188 per 1000 men aged 85 and over in The equivalent rates for women were 5 and 160 per Figure 12. Major causes of death, by sex and age, in Britain in 2002.

10 Cancers were the most common cause of death in Britain for people aged (Figure 12). Cancers accounted for 39 per cent of male and 53 per cent of female deaths in this age group. Lung cancer was the major cause of cancer death for men; for women it was breast cancer. For the age group 65 and over, circulatory diseases are the most common cause of death. In this age group, heart disease as a cause of death decreases with age, while strokes increase. Conclusion The increases in life expectancy in recent decades are encouraging, but much still needs to be done. Poor countries are making considerable progress against diseases such as diarrheal diseases, which are now becoming relatively cheap to combat. However, progress in poor countries is much slower in treating the increase in cardiovascular diseases, where effective treatments can be very expensive. But health costs are not just an issue in poor countries. The issue of how to pay for health services and the rising expectations we have of them is a major problem confronting governments in most rich countries today.