MORTALITY PATTERNS AND THEIR IMPLICATIONS

France MESLÉ and Jacques VALLINInstitut national d’études démographiques (INED), Paris

Summary

The diversity of mortality levels and patterns around the world is currently greater than ever. This directly results from the new historical perspective engaged two and half centuries ago, when some North-Western European countries started to become efficient in their fight against disease and death. But the road of progress has not been straightforward. Until the late 1960s, it was possible to rather clearly oppose high mortality levels of developed countries to the low levels of developing ones. Today, both groups of countries radically split into those that were the most successful and those that lagged behind. Many authors, starting with Abdel Omran and its epidemiological transition theory tried to find out the rationale for the historical mortality changes, and continuing with those who tried to extend Omran’s theory to the new facts that contradicted it and with those who preferred to try to assess a new theory, the health transition theory, to take in account non epidemiological factors. However the current situation if so complex that it is not possible to describe it as the result of only one stream of changes that could universally explain all the different trajectories of individual populations. It appears that the history of human mortality is made of the achievement of successive steps of development that occurred with quite different timing from one population to another, in order to produce at each step a divergence and then convergence wave. And a wave can easily start when the previous one is not completed. Thus explained, the large to-day inequity is far from being reduced. That would need that the most advanced population be stopped in their progress by a supposed biological limit of the human life span. A limit that nothing allows us to fix today.

Keywords : mortality, life expectancy, infant mortality, health transition, epidemiologic transition, death rate, cardiovascular diseases, infectious diseases, man made diseases, AIDS, developed countries, developing countries, world,

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Sub-Saharan Africa, Eastern Europe, Western countries, mortality forecasts, maximum life span, mortality theories

Introduction

Mortality was high in all human populations up until the eighteenth century. With sometimes brutal variations, the crude death rate stood around 40 per 1,000 population, more or less equivalent to the birth rate. However, crude death rate, obtained by dividing the number of deaths observed during one calendar year by the total mean population of the same year, does not depends only on the level of mortality but also on the age pattern of the population. Indeed, since mortality risks are much higher for old people than for young people, same mortality risks will give an higher crude death rate in a population where the proportion of old people is higher than in a population where such proportion is lower. This is the reason why demographers calculate the life expectancy at birth, which is the mean duration of life that would be experienced by the individuals of a hypothetical birth cohort that would be affected all along the life by age-specific deaths rates observed in the year for which it has been computed. It is an indicator of the level of mortality, independently from the age structure of the population, quite comparable across time and space. Until the eighteenth century life expectancy scarcely exceeded 25 years. Approximately half of all newborns died before the age of five and even 30% before the age of one. To easily focus on the historical importance of the latter, infant mortality rates are very simply computed by dividing the number of deaths under one year of age observed during one calendar year by the number of births observed during the same year. Of course this very simple indicator is also independent from the population age pattern and it allows to fairly represent mortality levels when in the past or more recently in developing countries mortality was very high and data too poor to compute life expectancy precisely.

From the eighteenth century on, the battle against the major epidemics became more efficient, largely thanks to political and administrative progress, while famines became less frequent as a result of agricultural development, improved means of communication, and the opening up of trade. Northwest Europe was the first to benefit from this. By the middle of the nineteenth century, life expectancy in England, the Scandinavian countries and the Netherlands,

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reached — and even exceeded — 40 years. In the second half of the nineteenth century, the health transition reached North America and Japan while at the same time spreading to southern and eastern Europe. But it did not reach Latin American and parts of Asia and the Middle East until the interwar period, and only spread to the rest of the world after World War II.

Boosted by the economic development that resulted from the industrial revolution, sanitary progress spread world-wide but with major discrepancies of time and pace. Some countries, such as Japan in the past and many developing countries today, benefited from the experience of others and caught up — sometimes even overtaking the forerunners. The result, until recently, was a broad range of situations. But in the past twenty years the trend has been towards a concentration of populations at the higher levels of life expectancy, while maintaining that range.

One might suppose that this trend will ultimately lead to equality of health and the realization, at last, of the World Health Organization’s (WHO) slogan “Health for all by the year 2000”. But things are never so simple. Some countries, notably in sub-Saharan Africa, clearly lag behind. Conversely, many developing countries are catching up and even overtaking the life expectancies of the developed countries, because they are winning the battle against infectious diseases but have yet to be hit by the increase in cardio-vascular diseases and cancers that struck most of the developed world during the 1950s and 1960s.

Is the future likely to see a possible convergence of all the countries in the world towards a life expectancy that some researchers place at 85 years (Fries, 1989; Olshansky and Ault, 1986)?. That would suppose that the most developed countries do not rise above their present rates, and that those who still lag behind rapidly catch up with them. Recent developments do little to confirm this hypothesis however.

I. The variety of situations today

All countries have been affected by the improvement in life expectancy and the worst situations today resemble the once-privileged situation in Europe, North America and Japan at the beginning of the century. Table 1 summarizes the mortality levels observed in all countries with a population of more than 15 million according to the three classic indicators, in three major regions of the

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world. Data used in this table are coming from systematic computations done by the Population Division of the United Nations. It is well known that the quality of these estimates varies a lot with the availability and the quality of national data. UN experts do their best to select the most reliable data from each country and to use the best indirect methods to estimate desired indicator that cannot be computed from direct observation. Indeed estimates for some developing countries must be considered as rough estimates and international comparison must be used with caution. Nevertheless, UN databases are the most appropriate to give a rather good overview of the actual diversity of situation.

Table 1. Mortality indicators for 2000-05 in 62 countries with a population of more than 15 million in 2005, ranked according to life expectancy at birth

(e0 = life expectancy at birth, IMR = infant mortality rate, CDR = crude death rate)

AREA, country Population e0 IMR CDR2005 2000-05 2000-05 2000-05

World 6514751 66.0 49.4 8.8 More developed countries 1215636 75.6 7.1 10.2 Intermediate countries (Less developed – Least developed) 4532300 66.6 43.5 7.6 Least developed countries 766816 52.7 87.9 13.3

Japan 127897 81.9 3.2 8.0Australia/New Zealand 24407 80.2 4.5 6.9

Australia 20310 80.4 4.4 6.8Western Europe (North without Baltic c., South, West) 426240 78.8 5.0 9.7

Spain 43397 80.0 4.2 8.7Italy 58646 79.9 5.0 9.9France 60991 79.6 4.2 9.2Germany 82652 78.7 4.3 10.3Netherlands 16328 78.7 4.7 8.7United Kingdom 60245 78.5 4.8 10.2

Northern America 332245 77.6 6.2 8.2Canada 32271 79.8 4.8 7.2United States of America 299846 77.4 6.3 8.3

Eastern Asia (without China and Japan) 96966 74.3 16.1 6.5Taiwan 22770 77.3 5.5 5.8Republic of Korea 47870 77.0 4.1 5.4Dem. People's Republic of Korea 23616 66.7 48.2 9.3

China (including Hong Kong and Macao, excluding Taiwan) 1290079 72.0 23.0 6.6Latin America (including the Caribbean) 557979 72.0 21.6 6.0

Chile 16295 77.9 7.2 5.0Mexico 104266 74.9 16.7 4.7Argentina 38747 74.3 13.4 7.7Venezuela 26726 72.8 17.0 5.0Colombia 44946 71.7 19.1 5.6Brazil 186831 71.0 23.6 6.3Peru 27274 69.9 21.2 6.2

South-Eastern Asia 557669 68.5 27.4 6.7Malaysia 25653 73.0 8.9 4.5Viet Nam 85029 73.0 19.5 5.2Philippines 84566 70.3 23.1 5.1Indonesia 226063 68.6 26.6 6.6

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Thailand 63003 68.6 10.6 8.6Myanmar 47967 59.9 66.0 10.2

Western Asia 212088 68.3 39.3 6.2Syrian Arab Republic 18894 73.1 16.0 3.6Saudi Arabia 23612 71.6 18.8 3.8Turkey 72970 70.8 27.5 5.8Yemen 21096 60.3 58.6 8.6Iraq 27996 57.0 81.5 10.6

Eastern Europe (including Baltic countries) 304847 67.9 13.4 14.3Poland 38196 74.6 6.7 9.6Romania 21628 71.3 14.9 12.2Ukraine 46918 67.6 12.8 15.8Russian Federation 143953 64.8 16.6 15.9

Northern Africa 189562 67.1 38.3 6.7Algeria 32854 71.0 31.1 5.0Egypt 72850 69.8 29.3 5.9Morocco 30495 69.6 30.6 6.0Sudan 36900 56.4 64.9 11.2

India 1134403 62.9 55.0 8.7South-central asia without india 511387 62.4 65.0 8.3

Sri Lanka 19121 70.8 11.0 7.3Iran (Islamic Republic of) 69421 69.5 30.6 5.5Uzbekistan 26593 66.5 55.0 6.8Kazakhstan 15211 64.9 24.1 10.6Pakistan 158081 63.6 67.5 7.7Bangladesh 153281 62.0 52.5 8.2Nepal 27094 61.3 53.9 8.7Afghanistan 25067 42.1 157.0 21.6

Melanesia, micronesia, polynesia 9003 60.5 50.7 8.6Southern africa 54900 52.5 46.4 13.8

South Africa 47939 53.4 44.8 13.5Tropical Africa (Eastern, Middle, Western) 677549 48.4 96.2 15.3

Ghana 22535 58.5 56.6 10.0Madagascar 18643 57.3 65.5 11.0Kenya 35599 51.0 64.4 13.2Ethiopia 78986 50.7 86.9 14.4Cameroon 17795 49.9 87.5 15.0United Republic of Tanzania 38478 49.7 72.6 14.6Uganda 28947 47.8 76.9 15.5Côte d'Ivoire 18585 46.8 116.9 16.5Nigeria 141356 46.6 109.5 17.5Democratic Republic of the Congo 58741 45.0 113.5 19.3Mozambique 20533 44.0 95.9 19.2Angola 16095 41.0 131.9 22.1

Source : United Nation 2006 World Population Prospects (for Taiwan, see http://www.moi.gov.tw/stat/english/).

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South Africa

Afghanistan

Sudan

Russian Federation

Iraq

Myanmar

Peru

Republic of Korea

Angola

Australia

SpainItaly

FranceGermany

NetherlandsUnited Kingdom

CanadaUnited States of America

Taiwan

Dem. People's Rep. of Korea

ChileMexico

ArgentinaVenezuelaColombia

Brazil

MalaysiaViet Nam

PhilippinesIndonesiaThailand

Syrian Arab RepublicSaudi Arabia

TurkeyYemen

PolandRomania

Ukraine

AlgeriaEgypt

Morocco

Iran (Islamic Republic of)Uzbekistan

KazakhstanPakistan

BangladeshNepal

GhanaMadagascar

KenyaEthiopia

United Republic of Tanzania

Côte d'Ivoire

Dem. Republic of the Congo

Sri Lanka

Uganda

Nigeria

Cameroon

Mozambique

Tropical Africa

Southern Africa

Melanesia, Micron. Polyn.

South-Central Asia

India

Northern Africa

Eastern Europe

Western Asia

South-Eastern Asia

Latin America & Caribbean

People's Republic of China

Japan

Australia/New Zealand

Western Europe

Northern America

Eastern Asia

40 45 50 55 60 65 70 75 80 85

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Figure 1. Life expectancy at birth in 2000-2005, in 62 countries with a population of more than 15 million in 2005 Source: United Nations, 2006 (for Taiwan, see http://www.moi.gov.tw/stat/english/)

In Angola, the least favoured nation today, the crude death rate is close to 22 per 1,000 (versus 18 in England/Wales, 20 in Japan and 22 in France in 1900), infant mortality is 132 per 1,000 (versus 154, 215 and 164 in 1900 for the same three countries respectively), and life expectancy at birth is 41 years (versus 47, 38 and 45). But however bad, these cases are still a far cry from the severe conditions that existed before the health transition and that still prevailed in many countries at the end of World War II.

Nevertheless, there is a broad disparity of situations. Going from one extreme to another in the six-country list, Angola’s life expectancy of 41 years is to be compared with Japan’s 82 (Figure 1). But this disparity does not simply contrast developed nations with developing ones. It occurs within the same region, for instance in South Asia where Afghanistan (life expectancy of 42.1 years) is almost as far removed from Sri Lanka (70.8 years) as it is from the Western countries. In Southeast Asia, life expectancy ranges from 59.9 years in Myanmar to 73 in Malaysia, while in North Africa it ranges from 56.4 years in Sudan to 71 in Algeria, and so forth.

0

20

40

60

80

100

120

140

160

180

35 45 55 65 75 85

Japan

Afghanistan

Angola

Côte d'IvoireDR Congo

Nigeria Tropical Africa

Life expectancy at birth (years)

Infant mortality rate (p. 1 000)

South Africa

0

5

10

15

20

25

35 45 55 65 75 85

Japan

United Kingdom

Syria

Saudi Arabia

UkraineRussia

Eastern Europe

Romania

Afghanistan

Angola

Life expectancy at birth (years)

Crude death rate (p. 1 000)

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Figure 2. Correlation between life expectancy at birth and infant mortality rates (a) and between life expectancy at birth and crude death rate (b) in

2000-2005(the white diamonds correspond to countries while the black squares correspond to regions)

Of the three indicators in Table 1, only two, life expectancy and the infant mortality rate are a true reflection of a populations’ state of health. The third, the crude death rate, obviously depends on the age distribution of the population. This is easy to see from Figures 2a and 2b. As it was said above, data plotted here are not all of the same quality. In particular, for some developing countries, the UN made indirect estimates of life expectancy, sometimes based on infant and child mortality rates. However, only countries with more than 15 million population are selected here and in only few of them data on adult mortality are totally lacking. Indeed if all low levels of life expectancy would have been deduced from infant mortality rates only, the correlation would be perfect for the left upper part of the graph, which is not the case.

Thus, Figure 2a confirms the close correlation between life expectancy and infant mortality; while Figure 2b reveals two distinct sets of countries: the industrial nations that are already demographically aged by the long-standing low birth rates, and the developing countries where the population pyramid still comprises a large proportion of young people. Indeed, some countries with fairly similar life expectancy levels, such as Chile and Germany (77.9 and 78.7 years) nevertheless have crude death rates that vary by a factor of two (5.0 for Chile versus 10.3 p. 1,000 for Germany).

One might be tempted to reject crude rates as a mortality indicator. However we believe it is useful to mention their distribution here, since it is the difference between the crude death rate and the birth rate which determines population growth, depending on countries’ stage of progress in their demographic transition. Comparing the crude death rate with specific mortality indicators thus broadens the diversity of health situations by placing it in its historic context.

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II. The end of the Third World concept

The range of mortality rates continued to grow from the onset of the health transition in Western Europe up to the moment it reached the countries of sub-Saharan Africa. However, until the 1950s the result was to create a wide gap between the northern countries and what was then called the Third World. In terms of major population groups, that was certainly the peak in divergence. From the 1950s to 2000, this gap began to close rapidly because of the variety of situations within the third world itself. From the health point of view, the “third world” notion had practically disappeared. Life expectancy and infant mortality rates were no longer common characteristics of the impoverished South. To illustrate this important aspect in developments during the past decades, we have shown (in Figures 3a, b and c) the total world population according to life expectancy at birth in three different five-year periods (1950-1955, 1975-1980 and 2000-2005), identifying developed and developing countries according to the United Nations definition.

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0

500

1000

1500

2000

30 40 50 60 70 80

Total population (millions)

Life expectancy (years)

1950-1955

Developed countries

Developing countries

Sub-Sah.Africa East. Europe

0

500

1000

1500

2000

30 40 50 60 70 80

1975-1980

East. Europe

Life expectancy (years)

Total population (millions)

Developing countriesDeveloped countries

Sub-Sah.Africa

0

500

1000

1500

2000

30 40 50 60 70 80

2000-2005

East. Europe

Life expectancy (years)

Total population (millions)

Developing countries

Developed countries

Sub-Sah.Africa

Figure 3 : Aggregate populations by life-expectancy

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In 1950-1955, most of the developing countries were concentrated around the 35-47 years life expectancy mark, far behind the major developed countries who were grouped around 65-70 years. In 1975-1980, the rich counties remained grouped together but had gained five years in the meantime, whereas the poor countries were suddenly scattered due to a large population whose life expectancy had grown much closer to that of the rich countries. In 2000-2005, the change is still more pronounced and the developing countries’ histogram shows a strong concentration in the 60-75 range, very close to that of the developed countries, even though these had gained a further five years. There is even an overlap between the ex-third world and the industrialized countries because of the recent divergence in the two first worlds: East and West. The central European countries are now in the same life expectancy range as China, while Russia stands in the same category as India. At the same time a fairly large portion of the developing nations, namely the countries of sub-Saharan Africa, lags far behind.

In 50 years, the geography of mortality has changed completely. The top map in Figure 4 is a clear illustration of the situation that prevailed at the beginning of the 1950s. The contrast between the North (including Australia and New Zealand) where life expectancy was above 60 years in most of the countries, and the South where it was less than 45 years, is striking. In-between these two very distinct worlds were the South and Central American countries, which began to progress during the interwar period, and had a life expectancy at birth of around 55 years. Half a century later, this simple dichotomy in the geography of mortality no longer applies (bottom map of Figure 4).

In 2000-2005, the map of life expectancies at birth reveals the contrasting situation in both sub-Saharan Africa and Eastern Europe with the rest of the world. While there has been a clear convergence for the great majority of countries, life expectancy remains at low levels in these two regions. The situation is particularly serious in Africa where 20 countries have still a life expectancy of less than 50 years. On the other hand, some countries have made spectacular progress. That is the case of China (Bannister, 1987) and Southeast Asia, as well as North Africa. This rapid progress contrasts with the relative deterioration of the situation in most of the Eastern European countries (Meslé, 1991), and especially in Russia (Meslé et al., 2000; Meslé et al., 2003).

Figure 4. Life expectancy at birth in the world in 1950-1955 and 2000-2005

Figure 5 shows life expectancy since 1950 in some of the most densely-populated countries of the world, with the most detail available. It reveals a dual

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trend of convergence/divergence. Among the industrialized nations, Japan advanced at a fast and regular pace compared with Russia, which caught up in the 1950s but fell back considerably after the mid-1960s. Between these two extremes, the US and France followed similar intermediate trajectories, with France being the more dynamic of the two at the start and end of that period.

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35

45

55

65

75

85

1950 1960 1970 1980 1990 2000

JapanFrance

USA

Russia

Mexico

China

China

Zambia

Nigeria

IndiaIndonesia

Life expectancy at birth (years)

Figure 5: Evolution of life expectancy in several large countries Sources: China: Banister 1987, and the UN 2006, US: Census Bureau: 1975, 1985 and 1992, Japan: Institute of Population Problems 1993, Nanjo et al. 1985, Russia: Meslé et al. 2003,

France: Vallin and Meslé 2001, other countries: UN 2006.

Among the developing nations, China largely succeeded in catching up with countries such as the US and France in the space of twenty-five years (from 1950 to 1975) despite the disastrous Great Leap Forward and caught up with Mexico – supposedly ahead among the developing nations – as early as 1965. However, since the end of the 1970s China has been advancing at a slower pace. India, and Indonesia have made rapid progress, particularly the latter, and have

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succeeded in considerably narrowing the gap with the industrial nations. We should not attach too much importance to the regular pace of the progress, which is pieced together in this figure from the United Nations’ five-yearly estimates, but the general trends are significant. This is especially true for the sharp divergence between these two countries and Nigeria or Zambia. Africa as a whole has, of course, made progress, but far less than the rest of the third world, and countries most affected by AIDS, such as Zambia, have lost several years of life expectancy.

III. The stages of health transition

According to Omran’s epidemiologic transition theory (1971), populations progressed from an “age of pestilence and famine” to an “age of degenerative and man-made diseases” by controlling infectious diseases. This simplification fitted in well with the advances, that, in the 1970s, had visibly occurred since the end of the war. In just 25 years, the discovery and propagation of simple medical techniques (vaccinations, antibiotics, DDT) had made considerable inroads against infectious diseases throughout the world, irrespective of levels of economic development. The 1950s and 1960s were times of great progress world-wide, and infant and child mortality fell sharply thanks to a large reduction in infectious mortality.

Since 1970 trends have become more complex. For the first time, progress levelled off in advanced countries. As Omran predicted, after infectious diseases had been defeated, the rise or stagnation in mortality from degenerative diseases seemed to prohibit more substantial progress in life expectancy. However, very quickly, weapons were found to fight these modern plagues and the cardiovascular revolution of the 1970s launched a new period of progress (Vallin and Meslé, 2001).

Without criticizing the basic premises of the epidemiologic transition theory, Jay Olshansky and Brian Ault (1986), followed by Richard Rogers and Robert Hackenberg (1987), introduced the idea of a "fourth stage" (Olshansky and Ault referred to "A fourth stage of the epidemiologic transition"; Rogers and Hackenberg referred to a "new" or an "hybristic" stage) during which the maximum point of convergence of life expectancies would increase thanks to achievements in the treatment of cardiovascular diseases. Jay Olshansky et al. (1990) set this new maximum at 85 years, the same as that chosen for all

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countries by the United Nations at the end of the 1980s (United Nations, 1989) to make their world population projections. Today, however, the 85-year threshold is strongly criticized by many authors who believe that such a limit cannot be determined (Vaupel, 2001; Carey and Judge, 2001; Barbi et al., 2003).

The very high life expectancy levels obtained by countries such as Japan or France are due to a combination of factors which together have contributed to the reduction of mortality, especially in old age. Among these factors, we may cite prevention campaigns against excess alcohol consumption and tobacco smoking, the systematic screening of hypercholesterolemia and hypertension, supply of new therapeutics, development of emergency care system, early screening of uterus or breast cancer.

Conversely, the gains achieved in the West did not spread to central and eastern Europe. Life expectancy in all East European countries began to plateau or even decrease, especially for males. The huge gap between two parts of Europe continued to widen for at least two decades, resulting in a yawning divide by the mid 1980s. The divergence was not only a matter of trends in life expectancy but the result of major changes in age and the cause-of-death structure of mortality (Meslé et al., 2003, Meslé and Vallin, 2002, Vallin and Meslé, 2004). However, from the mid 1980s, changes in these unfavourable trends differed in the former Soviet Union countries and in central Europe. While large fluctuations were observed in former USSR countries and gave rise to the current situation — which is even worse than the previous one — central European countries clearly returned to a steady improvement in life expectancy. Figure 6 summarises this succession of converging and diverging trends by focussing on three Western industrialized countries (France, the USA and Japan), two Central European countries (Czech Republic and Poland), and two former Soviet Union countries (Russia and Ukraine). The figure clearly shows the impressive convergence which brought all the industrialised countries very close to the 70-year level, and then the divergence between Western and communist countries from 1965 to 1985 and finally the divergence between Central Europe and the former USSR since 1985

15

55

60

65

70

75

80

1950 1960 1970 1980 1990 2000

Life expectancy at birth (years)

Japan

Russia

Ukraine

Czech R.

France

USA

Poland

Figure 6. Life expectancy at birth in central and eastern European countries compared to certain industrialized countries.

Source : Meslé and Vallin, 2007

The favourable trends observed in Western Europe back in the early 1970s have now spread to the countries in central Europe. These are similarly affected by the dramatic decrease in cardiovascular mortality. It is still difficult to assess the main determinants of such a reversal. The progress probably results from a combination of several factors, such as changes in diet, the growth of systematic prevention and screening, the spread of new forms of treatment, and cardiac surgery. Such a progress seems to extend to all the central European countries, including the Baltic states. Unfortunately this has still not reached Russia and the Ukraine (Meslé and Vallin, 2007).

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At the other end of the range of countries, we have already stressed the backwardness of sub-Saharan Africa in this respect. A growing number of countries in this region appear to be missing out on the phase of rapid progress experienced by other developing countries before them, largely because of the world economic crisis which has affected this area of the world more than any other. Not only did these countries fail to control the old infectious diseases such as tuberculosis, which is now re-emerging, or malaria for which drug resistance is increasing, but they also had to face the abrupt appearance of AIDS. In the 2006 United Nations projections, the present and future life expectancy trends for some of the African countries hardest hit by AIDS are very pessimistic (Figure 7).

35

40

45

50

55

60

65

1955 1965 1975 1985 1995 2005

Life expectancy at birth (years)

Zambia

Botswana

Zimbabwe

South Africa

Namibia

Kenya

Figure 7. Life expectancy at birth in the six countries hardest hit by AIDSSource: United Nations, 2006

In Botswana, for instance, United Nations estimates show a 17-year decrease in life expectancy from 64 years in 1985-1990 to 46 in 2000-2005. South Africa also suffers greatly from this increase in mortality due to AIDS,

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with an anticipated life expectancy of 49 years in 2005-2010 whereas it had reached 62 years in 1990-1995. In all regions, life expectancy is back to levels observed in the 1960s or even before. It will take several decades before these countries return to their 1990 levels.

IV. What assumptions for the future?

Yet these failures, however significant, do not question the epidemiologic transition theory as such. But they do indicate that some countries, for reasons inherent to their own history, economic development or culture, have encountered serious obstacles that have prevented them from completing certain stages of the transition. In Eastern Europe, the communist regimes relied almost too exclusively on the centralized administration of modern health care, whereas the shift towards a new stage of epidemiologic transition requires significant changes in behaviour, making individuals actively responsible for their own health. In addition, the economies of those countries, which were involved in a ruinous arms and space race with the West, did not have sufficient means to create an efficient health system for dealing with chronic diseases. The countries of sub-Saharan Africa, which are much more vulnerable to the generalized transmission of HIV due to widespread multiple partnership practices and the wide variability of partner age differentials, were very hard pressed by the epidemic just at a time when their very fragile economies were facing a global economic crisis which, in itself, had already wrought its inevitable consequences on poor local health services. Prevention methods, and, more recently, medical treatment for AIDS do exist and have proven to be effective in the northern countries, but for the time being Africa cannot afford them. In all cases, health care policies need to be improved and adequately funded for these countries to achieve their epidemiologic transition.

Abdel Omran's theory of epidemiologic transition may run up against a more profound contradiction in the renewed sharp rise in life expectancy observed in Western countries since the 1970s. Would adding a fourth phase to Omran's initial theory (Olshansky and Ault, 1986; Rogers and Hackenberg, 1987; Omran, 1998) as well as a fifth one to take on board AIDS (Olshansky et al., 1998) suffice to take into account this phenomenon? Perhaps the theory itself needs to be revised. First, as we have said, the reasons behind the emergence or resurgence of infectious diseases are no different from those governing the

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second phase of Omran's transition: the danger of infection can never be completely eradicated, only brought under control, and if the battle is fought in unfavourable conditions, all that has been gained may suddenly be lost, as shown by the dramatic situation in Africa. In fact, the situations in Eastern Europe and Africa do not so much challenge Omran's theory, as question the idea that life expectancies are rapidly converging towards a maximum level. In addition, Western advances in the treatment of cardiovascular diseases since the 1970s can be explained by the development of a new strategy based on advanced medical technology and changes in individual behaviour, especially diet. But not all countries are equally prepared to adopt these new strategies, as may be seen in eastern Europe. The question arises for many developing countries which have exceeded a life expectancy of 70 years: will they manage to catch up with Western countries in this, as they did with infectious diseases (Vallin, 1992)? Following the proposal made ten years ago by Julio Frenk et al. (1991), the concept of epidemiologic transition might usefully be replaced by the wider concept of "health transition", which would include not only the development of epidemiologic characteristics within the overall health situation, but also the ways in which societies respond to a health situation and vice versa (Caselli, 1995; Meslé and Vallin, 2006).

Arguably, every major improvement in matters of health is likely to lead first to a divergence in mortality, since the most favoured segments of the population benefit most from the improvement. When the rest of the population has access to the benefit of the improvement (through better social conditions, behavioural changes, health policies, etc.), a phase of convergence begins and can lead to a standardization until a new major advance occurs. The entire health transition process thus breaks down into successive stages, each including a specific divergence-convergence sub-process. From the 18th century to the present, at least two and perhaps even three of these successive stages have occurred or are occurring: the vanquishing of infectious diseases (Omran’s epidemiologic transition, in fact), the cardiovascular revolution, and finally the fight against ageing (Vallin and Meslé, 2004).

V. Divergence and convergence

After being powerless in the face of death for thousands of years, in the space of two centuries — from Molière’s doctors to the discovery of antibiotics,

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via Pasteur and his vaccines — humankind finally acquired efficient means with which to fight infectious diseases. At the outset this only benefited a tiny fraction of humanity in Western Europe, where these means had been discovered and developed, resulting in a deep division in the life expectancies of those countries and the rest of the world. Gradually however, these recipes for progress in health spread to southern Europe, North America, the East as far as Meiji-era Japan and finally to the third world after World War II. The initial divergence thus gave way to a general movement of convergence which peaked in the 1960s and inspired Omran’s theory of epidemiologic transition, but also blinded him to the possibility of other changes causes by other forms of progress.

We know the rest: in the thirty years from the 1970s to the end of the twentieth century the revolution in cardiovascular medicine broke through that ceiling which, according to Omran, capped all degenerative diseases. Once again, before the third world countries could catch up with the West, a new phase of deep divergence arose between Western countries in the industrialized nations which had developed the new technologies for treating cardiovascular disease, and the Communist countries with antiquated health strategies. The life expectancy in the West thus rose above the 76 years in Jean Bourgeois-Pichat’s table of biological mortality. It is true that since the fall of the Berlin Wall, a few countries from the former Communist bloc — those in central Europe and the Baltic — have also entered the “cardiovascular revolution”, and begun a new movement of convergence, but that is not the case with Russia, the Ukraine, or Byelorussia. And just to make matters more complicated, that was the moment when AIDS burst onto the scene and furthered aggravated the fragmentation in the third world, leading to a spectacular lowering of life expectancy in several African countries.

But the movement did not stop there. A new phase of divergence between the most advanced countries of the planet appears to have started during the last decade of the twentieth century. Whereas the rise in female life expectancy as a result of the cardiovascular revolution is slowing down in certain countries such as the US or the Netherlands, it is continuing at a regular, or even a faster pace in some countries such as France and Japan. These two countries appear to have reached a new stage in the battle against ageing, leaving the others behind.

However speculation increases when questions are raised about possible future mortality trends in countries where mortality has already dramatically

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decreased. What is the limit? Is there a limit? Those questions are at the heart of the debate today.

VI. Is there any limit to life expectancy growth?

An optimistic standpoint might envisage that mortality from the main causes of death, such as cardiovascular disease and cancer, will decrease further thanks to a better control of the risk factors and increasingly effective therapies. One might even expect that neuro-degenerative diseases, such as Alzheimer’s or Parkinson’s disease, may be controlled effectively. But many researchers believe that there will remain a hard core of pathologies, related to the physiological senescence of the body, that will be impossible to treat. Back in 1952, Jean Bourgeois-Pichat made a distinction between endogenous mortality, in theory unavoidable, and exogenous mortality, which depends on external factors (Bourgeois-Pichat, 1952). However the concept of endogenous mortality itself varies with time and medical progress. Cancer, for instance, was often considered to be an endogenous cause of death because it is closely linked to body ageing, but it also depends largely on external factors such as tobacco or infectious agents. Indeed, the distinction between endogenous and exogenous is quite vague since the frontier between avoidable and unavoidable mortality is not fixed but moves according to medical progress.

Mortality assumptions usually refer explicitly or implicitly to a biological limit to human life. The limit specific to the human species is generally estimated at around 120 years. Until now, life expectancy increased because an increasing number of people could hope for a life span that was growing ever closer to the possible maximum, but the maximum itself has remained unchanged. Moreover, that maximum was probably not the same for all. Assuming that future medical and biological progress allows us to avoid all causes of premature death and that a life span depends only on the ageing process, it is possible to produce hypotheses about the importance of individual variations. According to various authors, the mean of these theoretical individual life spans could range from 85 to 100 years (Olshansky et al., 1990; Duchêne and Wunsch, 1990).

Regarding the most advanced countries, one might reasonably ask whether limiting the ceiling to 85 years, as is assumed in the United Nations projections, does not constitute too pessimistic a view for the long term. Admittedly, this figure is the one put forward by the proponents of an unreachable biological limit

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to life (Fries, 1989, Olshansky et al., 1990). However, some demographers (Myers and Manton, 1984; Bourgeois-Pichat, 1988) as well as some biologists (Walford, 1984) vigorously refute such a hypothesis and believe that a technological revolution should, very soon, enable man to control the ageing process of cells thus making it possible to extend life expectancy beyond 100 years. Mortality trends in the extremely old would seem to support this second hypothesis (Kannistö, 1994, 1996). Whichever of these two hypotheses turns out to be true, the effects will only have a bearing on reality in the fairly distant future, it would be wrong to dismiss them as mere conjecture, for both will exert a strong influence on the ageing of populations already affected by recent gains in life expectancy at very advanced ages. These developments call for a reorganisation of industrial societies which will necessarily require some time to put in place.

VII. Conclusion

Leaving aside the slogan “Health for all in the year 2000”, recent world mortality trends shed light on the persistence or appearance of crucial issues in public health. The economic crisis affecting so many African countries, the resurgence of infectious diseases, the gradual backward slide of Eastern Europe and the uncertainty surrounding the biological limit to life, provide an abundance of public health issues that will surely count among the main problems to be tackled by economic and social policies in the coming decades.

If the extreme diversity of situations runs counter to the hopes raised by the WHO slogan, it may nevertheless be explained. The severe deterioration of the health situation as a result of AIDS in Africa is the cruel proof that advances in health cannot last if they are not accompanied by economic and social development. And this is certainly where Omran’s theory falls flagrantly short. Infectious diseases were obviously not the sole factor to be dealt with in prolonging human life, and Omran’s second error was to have not intuited this. Lastly, if we admit that every major source of progress naturally triggers off a first movement of divergence, because not every society is equally ready to benefit from it, it may be possible to untangle the web of current complexities. In order to achieve convergence again, the countries who lagged behind at the start must first obtain the means with which to benefit from it. But one divergence-convergence process does not have to be completed before another begins. The

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diversity of situations can continually increase, so long as there is scope for further progress in health. Uncertainties as to the biological limits of human life bring the phenomenon to its climax by opening the door to unlimited progress. Instead of converging in “health for all”, are we not on a path to a growing inequality of health situations that will only end when the whole of humankind is in a position to benefit equally from new health innovations?

Table 2. Trends in life expectancy by region and for the 62 countries of more than 15 million people in 2005, ranked according to the 2000-2005 value

Region and country Life expectancy at birth1950-55 1975-80 2000-05 2025-30 2045-50

World 46.4 60.2 66.0 71.9 75.4 More developed countries 66.1 72.2 75.6 79.8 82.4 Intermediate countries (Less developed – Least developed) 41.5 59.2 66.6 72.9 76.4 Least developed countries 36.2 46.2 52.7 61.4 67.2Japan 63.9 75.5 81.9 85.2 87.1Australia/New Zealand 69.6 73.3 80.2 83.8 85.9

Australia 69.6 73.5 80.4 83.9 86.0Western Europe (North without Baltic c., South, West) 66.6 73.1 78.6 82.1 84.3

Spain 63.9 74.3 80.0 83.2 85.4Italy 66.0 73.6 79.9 82.9 85.0France 66.5 73.7 79.6 83.0 85.1Germany 67.5 72.5 78.7 81.8 84.1Netherlands 72.1 75.3 78.7 82.0 84.0United Kingdom 69.2 72.8 78.5 81.9 84.1

Northern America 68.8 73.4 77.6 80.9 83.3Canada 69.1 74.2 79.8 83.2 85.3United States of America 68.9 73.3 77.4 80.7 83.1

Eastern Asia (without China and Japan) 50.6 66.7 74.3 78.4 80.6 Taiwan 59.3 71.6 77.3 81.4 83.5

Republic of Korea 47.5 64.8 77.0 81.4 83.5Dem. People's Republic of Korea 50.1 67.2 66.7 70.7 73.4

China (including Hong Kong and Macao, excluding Taiwan) 40.8 65.3 72.0 76.6 79.3Latin America (including the Caribbean) 51.4 63.0 72.0 77.1 79.6

Chile 54.7 67.1 77.9 80.7 82.2Mexico 50.8 65.0 74.9 79.6 81.3Argentina 62.5 68.5 74.3 78.5 80.7Venezuela 55.1 67.5 72.8 77.1 79.6Colombia 50.6 63.8 71.7 76.7 79.0Brazil 50.9 61.5 71.0 76.6 79.5Peru 43.9 58.4 69.9 75.6 78.2

South-eastern Asia 40.9 55.3 68.5 75.5 78.6Malaysia 48.5 65.3 73.0 77.5 80.1Viet Nam 40.4 55.8 73.0 77.9 80.3Philippines 47.8 60.1 70.3 75.8 78.7Indonesia 37.5 52.7 68.6 75.7 78.6Thailand 50.8 62.5 68.6 74.8 78.1Myanmar 36.3 56.1 59.9 69.9 74.6

Western Asia 45.2 60.1 68.3 75.2 78.3Syrian Arab Republic 45.9 61.2 73.1 77.5 80.0

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Saudi Arabia 39.9 58.7 71.6 76.3 79.1Turkey 43.6 59.5 70.8 75.5 78.5Yemen 32.5 44.2 60.3 70.4 75.0Iraq 45.3 60.4 57.0 72.1 76.1

Eastern Europe (including Baltic countries) 64.2 69.0 67.9 72.6 75.9Poland 61.3 70.9 74.6 78.6 80.9Romania 61.1 69.5 71.3 76.4 79.1Ukraine 65.9 69.4 67.6 72.0 75.2Russian Federation 64.5 68.0 64.8 69.7 73.4

Northern Africa 41.8 53.9 67.1 73.3 76.7Algeria 43.1 58.0 71.0 76.2 79.0Egypt 41.9 53.3 69.8 75.6 78.6Morocco 42.9 55.7 69.6 75.5 78.6Sudan 38.6 47.8 56.4 65.4 70.3

India 37.4 54.2 62.9 71.4 75.6South-central Asia (without India) 41.3 52.3 62.4 69.6 74.0

Sri Lanka 57.6 65.9 70.8 75.1 77.6Iran (Islamic Republic of) 44.9 57.7 69.5 75.4 78.4Uzbekistan 55.8 64.7 66.5 70.8 74.3Kazakhstan 55.0 64.2 64.9 73.2 76.9Pakistan 43.4 54.0 63.6 71.4 75.7Bangladesh 37.5 46.9 62.0 71.2 75.5Nepal 36.2 46.7 61.3 71.1 75.5Afghanistan 28.8 38.4 42.1 50.8 58.7

Melanesia, Micronesia and Polynesia 39.4 53.6 60.6 66.0 70.5Southern Africa 44.7 55.4 52.5 55.7 62.4

South Africa 45.0 55.5 53.4 56.0 62.6Tropical Africa (Eastern, Middle, Western) 36.9 46.7 48.4 57.6 64.4

Ghana 43.1 51.8 58.5 66.4 70.9Madagascar 36.7 46.9 57.3 65.6 71.3Kenya 42.3 56.2 51.0 61.2 67.2Ethiopia 34.1 44.5 50.7 60.8 67.3Cameroon 38.5 49.4 49.9 57.3 64.4United Republic of Tanzania 41.2 49.9 49.7 59.7 66.1Uganda 40.0 50.4 47.8 59.8 65.2Côte d'Ivoire 40.5 52.4 46.8 55.8 62.6Nigeria 36.3 44.5 46.6 54.4 62.1Democratic Republic of the Congo 39.1 47.8 45.0 53.3 60.9Mozambique 31.3 42.5 44.0 49.4 57.2

Angola 30.0 39.5 41.0 50.3 58.2Source : United Nation 2006 World Population Prospects (for Taiwan, see http://www.moi.gov.tw/stat/english).

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GlossaryCardiovascular revolution. The new approach of cardiovascular diseases that

led the Western industrialized countries to reduce dramatically their cardiovascular mortality, starting in the 1970s.

Crude death rate. Number of deaths observed during one calendar year divided by the total mean population of the same year. This indicator depends not only on the level of mortality but also on the age pattern of the population. Indeed, since mortality risks are much higher for old people than for young people, same mortality risks will give an higher crude death rate in a population where the proportion of old people is high than in a population where such proportion is low.

Degenerative diseases. Diseases originated in the degradation of the human body either because of ageing process (like many cardivascular diseases) or because of disruption of physiological equilibriums (like cancer). This concept oppose that of diseases provoked by the invasive action of external agents like infectious diseases or accidents.

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Endogenous mortality. Concept proposed by Jean-Bourgeois Pichat in the early 1950s to characterize mortality due to biological weakness or deficiencies of individuals. Opposed to exogenous.

Epidemmiologic transition. The words used by Abdel Omran to found his explanatory theory of historical mortality change on the basis of the change causes-of-death patterns.

Exogenous mortality. Concept proposed by Jean-Bourgeois Pichat in the early 1950s to characterize mortality due to external agression (mainly infectious diseases). Opposed to endogenous.

Health transition. Expression used by Julio Frenk and many other authors to found a new explanatory theory of historical changes in mortality, not only based on cause-of-death patterns but also on the type of development and the level of achievements of the societies.

Infant mortality rate. Number of deaths under one year of age observed during one calendar year divided by the number of births observed during the same year.

Life expectancy. Mean duration of life that would be experienced by the individuals of a hypothetical cohort that would be affected all along the life by age-specific deaths rates observed in the year for which it has been computed. Life expectancy can be calculated at birth (it is then the total mean duration of life) or at any age (the mean duration of life after that age). For a population, life expectancy at birth is an indicator of its level of mortality independent of its age structure. This indicator allows to compare mortality of very different populations and to trace actual mortality changes of a changing population.

Man made diseases. Diseases caused by human activity or behaviour, like work accident, professional diseases, traffic accident, alcoholism, tobacco-related diseases, suicide, homicide, etc.

Third World. An expression forged in the 1950’s by Alfred Sauvy to focus on the political emergence of third world in between the first one (the industrialized Western countries) and le second one (the Eastern countries under communist regime) then opposed by the cold war. The Third World was made of numerous poor countries getting soon their political independence. From a demographic point of view they were charaterized by very high levels of fertility and mortality and by heavy proportions of young children as well as by an accelerating population growth. Today, there are so huge differences in mortality and fertility among these countries that the concept no longuer fit with their actual situation.

Biographical sketchesFrance Meslé. Medical Doctor and demographer, France

Meslé is directrice de recherche at the Institut national d’études

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démographiques (INED) in Paris, where she heads the research unit « Mortalité, santé, épidémiologie ». Her main works deal with mortality and causes of death in many different countries She is particularly involved in long run mortality change analyses, based on the reconstruction of cause-of-deaths statistics according to a constant medical definition. For many years, she heads a broad project on the health crisis that hit countries of the ex-USSR since the 1960s, in collaboration with the Centre for Demography and Human Ecology in Moscou, the Max Planck Institute for Demographic Research in Rostock and several other research teams from former Soviet Republics. She has been responsible for the creation of the INED Website and chief redactor of the European Population Journal from 2000 to 2005. She teaches doctoral students both in Paris and Rostock, Germany. She is author or co-author of several books and of many articles published in demographic or epidemiological journals.

Jacques Vallin. Doctor in economics and demographer Jacques Vallin is directeur de recherche émérite at INED. He mainly explored two research fields, starting with population growth components in developing countries and then dealing with mortality trends and cause-of-death patterns in developed countries. He founded with France Meslé a method to reconstruct long term series of cause-of-deaths statistics according to a constant medical definition, first applied to 1925-1978 French data. A method that allowed later to make the same type of reconstruction in different countries, including the former Soviet Union countries. From 1994

to 1997 Jacques Vallin has been appointed as director of the Centre français sur la population et le développement (CEPED) to straighten its reseach activity and publications. Back to INED, he founded the research unit « Population et développement » and developed research activities in the research unit « Mortalité, santé, épidémiologie ». Member of the IUSSP (International Union for the Scientific Studiy of Population) Council (1993-97), then vice-president (1998-2001) and President (2002-2005), he is now Honorary President of the Union. He is author or co-author of about 15 books and hundred of articles published in demographic or epidemiological journals.

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