Life expectancy at birth - World Health Organization

[Pages:22]Chapter 2

Measuring health

Measuring health

I n view of major limitations imposed by the lack of suitable measurements that can capture the meaning of health as defined in the WHO Constitution ("Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity") this assessment of health trends uses

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A. Life expectancy at birth -- target: above 60 years

Above 60 years 60 years or less

1955

1975

1995

2025

68%

60%

86%

96%

32%

40%

14%

4%

B. Under-5 mortality rate -- target: below 70 per 1000 live births

Below 70 70 and above

1955

1975

1995

2025

70% 30%

47% 53%

64% 36%

94% 6%

C. Infant mortality rate -- target: below 50 per 1000 live births

Below 50 50 and above

1955

1975

1995

2025

81%

70%

60%

94%

19%

30%

40%

6%

a Percentages of the total population of all Member States.

LYT 98008

conventional indicators such as life expectancy, mortality and morbidity. Efforts are under way, however, to develop indicators of positive health such as health expectancy and its variants, but problems of standardization of definitions and comparability of values derived inhibit their usage for trend assessment at this stage.

The Global Strategy for Health for All by the Year 2000 (HFA2000) set the following guiding targets:

life expectancy at birth above 60 years;

infant mortality rate below 50 per 1000 live births;

under-5 mortality rate below 70 per 1000 live births.

In 1997, nearly 3.8 billion people (64% of the global population) lived in at least 106 countries that had reached those values. In 1975, there were at least 1.2 billion (30% of the global population) living in 69 countries. At least 102 countries (60% of the global population) reached all these values in 1995. The percentage of the global population living in countries which have reached these values since 1955, and which are expected to reach them by 2025, are shown in Fig. 1. There is, however, increasing evidence that as national average values are beginning to converge, internal disparities among population groups are widening.

Life expectancy at birth has increased globally by 17 years, from 48 in 1955 to 65 in 1995, and is projected to reach a level of 73 years by 2025, when it is expected that there will be no country with a life expectancy

39

% of survivors % of survivors

LYT 98023

The World Health Report 1998

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0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85+ Age

Least developed countries

100 FBJH

90 80 70 60 50 40 30

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B

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Age

B 1955 J 1975 H 1995 F 2025

40

at birth below 50. Even for the least developed countries (LDCs), the increase was about 15 years (from 37 in 1955 to 52 in 1995). The increase is expected to be 13 years between 1995 and 2025, when life expectancy for these countries will reach 65. In all, more than 5 billion people now live in 120 countries where life expectancy at birth is above 60. About 890 million people live in 26 countries where life expectancy at birth increased by 10 years or more between 1975 and 1995. About 1 billion people live in 56 countries where a similar increase is expected between 1995 and 2025. Such spectacular progress is not shared by all, however. More than 50 million people are still living in countries with a life expectancy at birth below 45. About 300 million people live in 16 countries which experienced a decrease in life expectancy at birth between 1975 and 1995. The range in national values for life expectancy at birth is expected to decrease from 43 years in 1955 to 31 in 2025.

Some of the population who are likely to be alive by the end of the 21st century are already born and alive today. Their survival rates have

been increasing significantly since 1955. As shown in Fig. 2, the overall trend is that global survival rates ? the chances of surviving 5, 20, 65 or 80 years ? have improved during the period 1955-1995. The same is true of the equivalent survival rates in the LDCs, but the percentages are considerably lower than the global percentages. For every 100 babies born in 1995, globally 70 are expected to live to at least 65 years, but in the LDCs only 47 are expected to do so. Globally for every 100 persons aged 20 in 1995, about 70 are forecast to survive at least 50 years (to age 70). Only 50 are likely to survive to this age in the LDCs.

Mortality trends

In its search for a simple and meaningful measure of health, WHO proposed in its second Report on the World Health Situation (in 1963), the proportional mortality ratio ? the number of deaths at age 50 and above as a percentage of deaths at all ages ? as a possible indicator. Applying this measure to study historical trends, globally the proportional mortality

Measuring health

ratio increased from 34% in 1955 to 45% in 1975, and 58% in 1995; it is expected to be around 80% in 2025. Here again disparities are striking ? in 1955, the LDCs had a value of 20% compared with 27% for other developing countries and 75% for the developed market economies; in 1995, the LDCs had a value of 26%, other developing countries 56% and the developed market economies 91%.

Overall mortality adjusted for age and sex composition of the population declined globally from 1860 deaths per 100 000 population in 1955 to 910 deaths per 100 000 in 1995 ? a 50% reduction ? and is projected to fall further to 610 deaths per 100 000 in 2025; for the LDCs, however, the standardized death rate fell by more than 40% from 1955 to 1995 and should be about 950 deaths per 100 000 in 2025. There was also a reduction globally of 67% from 1955 to 1995 in death rates among children under 5 and of 66% among those aged 5-19. Among those aged 20-64, the reduction was about 50%. In respect of those aged 20-64, death rates declined by 56% for females but only 49% for males. Here too, while age- and sex-specific mortality has been falling, the pace of decline is not uniform.

Fig. 3 shows the number of deaths at different ages and their distribution expressed as a percentage of total deaths. The general trend in the percentage of deaths occurring in the various age groups, both for the developed market economies and for the LDCs, is downward, except in the age group 65 and above. Overall, the number of deaths worldwide was the same in 1995 as in 1955 but with a significant decline of about 50% among children under 5, and of about 30% in the age group 5-19. There was an increase of about 5% in the working population aged 20-64. However, a

relatively small reduction of 6% was experienced by the female population in the reproductive age group 15-49. A comparison of the age distribution of total deaths worldwide and their trends reveal a changing pattern both for the developed market economies and the LDCs. Less than 2% of total deaths in the developed market economies in 1995 occurred among the population aged below 20, and about 1% is projected for 2025. In the LDCs however, the decreasing trend in the proportion of deaths among children, and a rapid increase in the proportion of deaths among older people, are noticeable. In the case of children, the proportion was nearly

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Age groups

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