Beyond Six Billion Forecasting the World's Population (2000) / Chapter Skim
Currently Skimming:
Mortality
Mortality
Pages 114-155
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 114... ...
It is not a prediction of future mortality. Other summary measures are possible, such as the median age at death, the age at which exactly half of a hypothetical cohort of births exposed to particular mortality rates would die, or the modal age at death, the age at which the largest single number of deaths would occur.
|
From page 115... ...
The other developing regions Latin America and the Caribbean, Asia, and the Middle East and North Africa each have life expectancies between 66 and 70. Industrial countries are experiencing the highest life expectancies ever observed.
|
From page 116... ...
——- 1996 (81.5) / 80 Age FIGURE 5-2 Age patterns of female mortality and life expectancies, Sweden, 1900-1996.
|
From page 117... ...
Transition in Industrial Countries The transition to higher life expectancies in industrial countries was not entirely smooth and continuous. Regular progress was interrupted by occasional setbacks, periods of stagnation, and sometimes rapid improvement.
|
From page 118... ...
To the extent that changes in weather patterns affect the diversity and size of infective agents and vectors, these two explanations are complementary (Galloway, 1986~. First Stage The first stage of transition, which occurred in Western Europe between 1700 and 1800, saw a reduction in the magnitude and frequency of fluctuations in mortality, but little average improvement in life expectancy.
|
From page 119... ...
In England and Wales in a roughly comparable period, however, rates fell fastest between the ages of 1 and 30, with little improvement in infant mortality or mortality in middle age (Wrigley and Schofield, 1981; Keyfitz and Flieger, 1968~. Among the reasons for the mortality declines were better standards of living, improved health behaviors, and various public health measures.2 Standards of living continued to improve from the previous stage, contributing to better nutritional intake and increasing individual resistance to some infectious diseases, particularly such diseases of the respiratory system as influenza, pneumonia, bronchitis, and respiratory tuberculosis (McKeown and Record, 1962; McKeown, 1976, 1988; Fogel, 1986, 2Improved medical knowledge and public health measures alone could not have been responsible for such large improvements.
|
From page 120... ...
These effects were only partly countered by rising levels of urbanization, which facilitated disease transmission (Woods and Woodward, 1984~. Third Stage The third stage of the transition saw an acceleration of mortality decline, with life expectancy rising by about one-third of a year per year, propelled by a new set of factors.
|
From page 121... ...
. Fourth Stage Mortality reductions are continuing in industrial countries, and a fourth stage of transition can be identified beginning around 1960.
|
From page 122... ...
We also plot life expectancies for 5year periods from vital-registration data for Sweden from the mid-18th century onward as an example of a quantitatively but not qualitatively different trajectory. The graph illustrates various characteristics already noted of the mortality transition in industrial countries.
|
From page 123... ...
The fourth stage, with reductions in old age cardiovascular mortality, reflects improvements in diagnosis and drug-based therapies, reinforced by behavioral changes, particularly the reduced prevalence of smoking. Transition in Developing Countries By and large, the mortality transition in developing countries has been driven by the same factors as in industrial countries but has proceeded much faster, with unprecedentedly rapid gains in life expectancy.
|
From page 124... ...
These countries started transition early, before World War II. By the early 1950s, most already had life expectancies of 55 years or higher, equivalent to the start of the third stage of mortality transition in industrial countries.
|
From page 125... ...
Delayed Transitions The second group of countries are those with life expectancies between 55 and 70 years, which roughly correspond to the boundaries of the third transition stage for industrial countries. These countries are scattered in all developing regions and include Brazil, Colombia, and E1 Salvador; China, India, and Indonesia; Algeria, Egypt, and Turkey; and Ghana, Kenya, and Mauritius.
|
From page 126... ...
SOURCE: Data from United Nations (1999~. Very Delayed Transitions All countries in the third group have life expectancies below 55 years.
|
From page 127... ...
In periods when mortality decline was driven by gradually improving, cumulative factors, such as spreading socioeconomic development, simple though nonlinear extrapolation would have been a defensible strategy and would have yielded satisfactory results. But in periods when mortality decline was driven by less predictable events, such as medical discoveries or implementation of public health measures, simple extrapolation would have been more problematic.
|
From page 128... ...
Extrapolation of life expectancy trends must also confront a possible change in trend when mortality reaches very low levels. At the levels reached in industrial countries today, for instance, most improvements must occur at ages above 60.
|
From page 129... ...
The preceding rate is fit into a logistic function that has a defined minimum for all countries of 20 years for either sex and a maximum of 83.3 years for males and 90 years for females. The gap between males and females corresponds to the difference between male and female life expectancies in industrial countries around 1985 (Bulatao and Bos, 1989; Bos et al., 1994~.
|
From page 130... ...
. The figure shows that one group of forecasts projected life expectancies as too high by a few years, another group projected them too low by about as much.
|
From page 131... ...
The digits after this designation indicate We year of the forecast, so that WB83 is the World Bank's 1983 forecast. in trends such as these are difficult to predict, but, given the fairly advanced transition stages that the largest countries of the world have reached, the broad overall trend in life expectancy appears to have been fairly predictable, at least over shorter time spans.
|
From page 132... ...
More important, the figure shows three important patterns: for industrial countries, for most developing regions, and for Sub-Saharan African countries in particular. For industrial countries, increases in life expectancy have been underprojected.
|
From page 133... ...
Projecting life expectancy in developing regions as following the path of industrial countries appears to be appropriate, but with developing countries improving quite fast, forecasters may have slightly underestimated the pace of improvement. This is not the case, however, for countries of Sub-Saharan Africa.
|
From page 134... ...
FIGURE 5-8 Observed U.S. life expectancies and various projections by the U.S.
|
From page 135... ...
Underestimating the pace of these latecomers' mortality transitions has been the source of errors in projections for most developing regions. · Third, how could unexpected events alter the course of future mortality?
|
From page 136... ...
Such factors could produce occasional rapid gains in life expectancy that need not be spread evenly across age groups or periods. Some postulate that the recent, very rapid reductions in agespecific mortality rates at older ages observed in Western Europe could even accelerate.
|
From page 137... ...
9This relationship can be maintained for a considerable period if mortality at older ages is decreasing slowly, say by less than 1 percent annually. The relationship is premised on the current rate of mortality increase with age in industrial countries.
|
From page 138... ...
While no simple solution exists to projecting mortality at these low levels, however, two alternative approaches not in general use may be worth further development. First, short-term and medium-term projections might try instead to extrapolate age-specific mortality rates rather than relying on age patterns linked to life expectancy.
|
From page 139... ...
From these expectations about future trends, we can draw several implications for projecting mortality in countries with recent mortality transitions. First, such projections must be recognized as more uncertain than projections for industrial countries, given the possibility of wider and
|
From page 140... ...
Third, projection accuracy would benefit from detailed study of the changes in risk profiles expected to produce future mortality declines. Table 5-1 summarizes some of the risk profiles for the three groups of developing countries.
|
From page 141... ...
Understanding the nature and likelihood of such changes in risk profiles could increase the robustness of mortality projections. Linking risk profiles to mortality rates has been tried with some success (Dowd et al., 1999)
|
From page 142... ...
Disruptions can, however, be more severe. Of the wars and civil conflicts in the last 50 years, four, outside Sub-Saharan Africa, produced sufficient decline in life expectancy to lead to sharp change in population growth rates: the Cambodian genocide (where life expectancy declined
|
From page 143... ...
Emerging Infectious Diseases: The Case of HIV/AIDS Future mortality declines may be slowed or halted by epidemics of new infectious diseases or resurgent older diseases (such as influenza, tuberculosis, and malaria) , particularly in countries with poorer infrastructure and health conditions.
|
From page 144... ...
\ \ \ / / Zimbabwe \~/' 1 970 1 990 2010 FIGURE 5-9 Impact of HIV/AIDS: Estimated and projected life expectancy in South Africa and Zimbabwe, according to the U.N. and the World Bank.
|
From page 145... ...
Recent prevalence estimates suggest that the epidemic might still become demographically significant in India and Southeast Asia but is unlikely to make rapid progress elsewhere (United Nations, 1998; see also National Research Council, 1996~. Projecting Mortality Crises Whether the types of events that produce mortality crises can be predicted or not is beyond the scope of this report; this depends on research in other fields, such as biology and medicine, politics, climatology, environmental science, and even astronomy.
|
From page 146... ...
A larger group of developing countries started transitions only after World War II and now have life expectancies between 55 and 70 years, similar to the third stage for industrial countries. These transitions have benefited from the diffusion of health care knowledge and its effective application.
|
From page 147... ...
Future Trends Projections of future mortality trends can continue to build on the record of rising life expectancies. There is in fact no theoretical or empirical basis for believing that life expectancy will reach some absolute limit in the foreseeable future.
|
From page 148... ...
Experimentation is advisable with alternative procedures for projecting mortality. At high life expectancy levels, one possibility is to investigate projecting age-specific mortality rates.
|
From page 149... ...
This approach also requires projecting risk profiles into the future, which may involve the development of structural equation models relating these profiles to broader socioeconomic conditions. Research in these two areas would probably also be useful in improv~ng mortality projections at low life expectancy levels.
|
From page 150... ...
Vaupel 1992 Slowing of mortality rates at older ages in large medfly cohorts. Science 258:457461.
|
From page 151... ...
1989 Second Thoughts on the European Escape from Hunger: Famines, Price Elasticities, Entitlements, Chronic Malnutrition, and Mortality Rates. Working Paper Series on Historical Factors in Long Run Growth, No.
|
From page 152... ...
1986 Past and future life expectancy increases at later ages: Their implications for the linkage of chronic morbidity, disability, and mortality. Journal of Gerontology 41:672-681.
|
From page 153... ...
1980 Causes and consequences of mortality declines in less developed countries during the twentieth century.
|
From page 154... ...
Szreter, S 1988 The importance of social intervention in Britain's mortality decline circa 18501914: A reinterpretation of the role of public health.
|
From page 155... ...
Romo 2000 How mortality improvement increases population growth. In a chapter on "Population dynamics," pp.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.