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Jamison DT, Feachem RG, Makgoba MW, et al., editors. Disease and Mortality in Sub-Saharan Africa. 2nd edition. Washington (DC): World Bank; 2006.

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Disease and Mortality in Sub-Saharan Africa. 2nd edition.

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Chapter 2Levels and Trends in Mortality in Sub-Saharan Africa: An Overview

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One of the major achievements of the twentieth century in Sub-Saharan Africa is the unprecedented decline in mortality and the corresponding increase in the expectation of life at birth. At the dawn of the twentieth century, Sub-Saharan Africa was characterized by extremely high under-five mortality levels and by low life expectancy at birth. By the end of the century, however, mortality among children under five had decreased from about 500 per 1,000 live births to about 150 (World Bank 2005). Similarly, the average length of life, which was less than 30 years about 100 years ago, had increased to more than 50 years by the early 1990s. Much of the mortality decline happened in the second half of the twentieth century, the fastest rate of decline occurring in the first decades after World War II (Hill 1991). In the 1990s, mortality decline stalled for the region overall, with many countries experiencing reversals in the upward trend in life expectancy largely because of AIDS mortality.

This overview focuses on the period between 1960 and 2005. This period roughly corresponds to the postcolonial era in many countries in the region, in which large economic and social changes occurred. Some of these changes were beneficial to the health of the population (such as economic growth and increasing access to health interventions), whereas others are associated with increasing exposure to risk factors that lead to increased morbidity and mortality (such as increasing exposure to risks for noncommunicable diseases or the spread of new and reemerging communicable diseases). Therefore, monitoring mortality levels and trends in the Sub-Saharan region provides not only a direct reflection of the health status of populations but also an indirect gauge of the effects of economic, political, and epidemiological turbulence that faced the region.

Indicators of Mortality Levels and Trends

In this overview chapter, two indicators of mortality are used to assess levels and trends for Sub-Saharan Africa, its subregions, and countries. The infant mortality rate, calculated as the proportion of newborns in a given period that do not survive to their first birthday, is a standard measure not affected by age structure and therefore suitable to use for comparisons over time and across regions. Life expectancy at birth, calculated as the average number of years a newborn would live if subject to the mortality rates for a given year, is used to compare the force of mortality across the entire age spectrum. The dearth of reliable data is one of the main problems confronting the study of mortality levels and trends in Sub-Saharan Africa. Although vital registration systems exist in most countries in the region, they usually do not produce reliable data. In the absence of reliable vital registration systems and good quality census data that are needed for direct calculation of infant and child mortality rates, demographers have developed indirect methods for obtaining these vital statistics from incomplete and often defective data. However, over the past 30 years, information available for the study of mortality patterns, particularly among children under age five, has improved dramatically. The improvement in information is largely due to the implementation of large-scale household survey programs, such as the World Fertility Surveys (WFS) program of 1972–84, the Demographic and Health Surveys (DHS), and UNICEF's Multiple Indicator Cluster Surveys (MICS). Of all these survey programs, the DHS has had the largest impact on data availability, analysis, and report dissemination. About 70 DHS surveys have been conducted in 33 of the 46 major countries in Sub-Saharan Africa.

Apart from the DHS-type surveys, Sub-Saharan Africa has an extensive network of longitudinal study sites. At least 19 such study sites exist in the region and their data have been invaluable in deriving mortality estimates by age as well as model life tables that show how the age pattern of African mortality differs from the model life tables constructed by Coale and Demeny (1983) and United Nations model life tables (INDEPTH Network 2001). The main problem with this source is that most of these longitudinal study sites are based in rural settings and are scattered throughout the whole region and therefore provide estimates of unknown generalizability. The locations of the sites are neither systematically planned to represent the Sub-Saharan Africa region nor do they adequately represent the countries in which they are located.

In this chapter the estimates for countries and subregions are those issued most recently by the United Nations Population Division; the estimates are based on a variety of sources, including surveys, censuses, and demographic modeling. The delineation of geographic subregions used are those defined by the United Nations.

Mortality Levels and Trends

The following section will provide a comparison of indicators of mortality trends discussed above, first comparing trends in life expectancy and infant mortality in Sub-Saharan Africa and other regions, followed by a comparison of these mortality indicators for subregions within Sub-Saharan Africa.

Sub-Saharan Africa Relative to Other, Less Developed Regions

Sub-Saharan Africa is, by far, the region of the world with the highest level of mortality. Overall life expectancy at birth is 46 years, whereas in Asia, the region with the second lowest life expectancy, it is 67.

As shown in table 2.1, the disparity between Sub-Saharan Africa and other regions of the world has widened since the 1960s. In that decade the difference in life expectancy with the Asian region was only 6 years, but this has grown to almost 21 years now. And, whereas all other regions have experienced uninterrupted increases in life expectancy, in Sub-Saharan Africa life expectancy peaked in the early 1990s at 50 years, and has since fallen back by almost 4 years.

Table 2.1. Life Expectancy at Birth for World and UN Regions, 1960–2005.

Table 2.1

Life Expectancy at Birth for World and UN Regions, 1960–2005.

Declines in infant mortality rates in Sub-Saharan Africa started to slow down considerably in the 1990s. These slow declines have meant that Sub-Saharan Africa has lagged more and more behind other regions and hence the mortality gap has widened (table 2.2).

Table 2.2. Infant Mortality Rates for World and UN Regions, 1960–2005(per 1,000 live births).

Table 2.2

Infant Mortality Rates for World and UN Regions, 1960–2005(per 1,000 live births).

Subregional Differences in Mortality

In Sub-Saharan Africa as a whole, infant mortality rates declined from 149 per 1,000 live births in the 1960s to about 101 in 2005—a 32 percent decline over a period of 35 years. Toward the end of the last decade of the twentieth century, the decline in infant mortality rates leveled off, decreasing only slightly for the region as a whole.

In regard to subregional disparities, infant mortality rates are highest in West Africa and in Middle Africa and have consistently been so from 1960 (table 2.3). The infant mortality rate declined somewhat faster in West Africa, and as a result, Middle Africa is currently the subregion with the highest rate. Of all subregions of Sub-Saharan Africa, countries in Southern Africa have had the lowest infant mortality rates. For example, in 1960 the rate was 42 percent lower than in other subregions, and even with increasing overall mortality in the 1990s, the infant mortality rate in Southern Africa was still less than half the average for Sub-Saharan Africa in 2000.

Table 2.3. Infant Mortality Rates for Sub-Saharan Africa and UN Subregions, 1960–2005(per 1,000 live births).

Table 2.3

Infant Mortality Rates for Sub-Saharan Africa and UN Subregions, 1960–2005(per 1,000 live births).

Life expectancy at birth has increased 3.5 years for the continent as a whole since 1960, but it is now lower in Southern Africa than in the 1960s (table 2.4). All the subregions reached peak levels of life expectancy about 1990, but they have since shown a decline, largely due to AIDS mortality. Nowhere has the decrease in life expectancy been steeper and greater than in Southern Africa, where 40 years of increases in life expectancy were reversed in a period of 10 years.

Table 2.4. Life Expectancy at Birth for Sub-Saharan Africa and UN Subregions, 1960–2005.

Table 2.4

Life Expectancy at Birth for Sub-Saharan Africa and UN Subregions, 1960–2005.

Country Differences in Mortality

Figure 2.1 illustrates the differences in the levels and trends in the infant mortality rate in selected Sub-Saharan Africa countries. The rates vary from 15 in Mauritius, to 165 in Sierra Leone, and the rates of change from 1960 to the present differ from about 20 percent in the Democratic Republic of Congo, Liberia, Rwanda, and Sierra Leone to over 50 percent in countries in Southern Africa. It is noteworthy, however, that infant mortality has declined in all countries since 1960.

Figure 2.1

Figure 2.1

Infant Mortality Rate in Selected Countries, 1960–2005 (per thousand) Source: Adapted from United Nations 2005.

Figure 2.2 shows country patterns in life expectancy at birth. The range in current levels is about 35 years, from a high of 72 in Mauritius to a low of 37 in Zimbabwe and Zambia. Recent trends are clearly negative in many countries, where increases in adult mortality resulting from AIDS have led to a decline in overall life expectancy. Most of these countries experienced the highest life expectancies during 1985 to 1990 and have since declined to below the levels in 1960.

Figure 2.2

Figure 2.2

Life Expectancy in Selected Countries Source: Adapted from United Nations 2005.

References

  1. Coale, A., and P. Demeny. 1983. Regional Model Life Tables and Stable Populations. New York: Academic Press.
  2. Hill, A. 1991. "Infant and Child Mortality: Levels, Trends and Data Deficiencies." In Disease and Mortality in Sub-Saharan Africa, ed. R. G. Feachem and D. T. Jamison, 37–74. New York: Oxford University Press.
  3. INDEPTH Network. 2001. Population and Health in Developing Countries. Vol. 1. Ottawa: International Development Research Centre.
  4. United Nations. 2005. World Population Prospects. The 2004 Revision. New York: United Nations.
  5. World Bank. 2005. World Development Indicators. Washington, DC: World Bank.
Copyright © 2006, The International Bank for Reconstruction and Development/The World Bank.
Bookshelf ID: NBK2292PMID: 21290653
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