30 Health transition, mortality concepts and patterns

Gautam Kshatriya and Jyoti Mishra

Contents:

1. Introduction to Health transition

2. Theories given for health transition

3. Transition Models

4. Modifications in the theory of Epidemiological transition

5. Mortality Concepts and Patterns

6. Exceptions to the theories of transition

7. Global burden of disease

Learning Objectives:

To thoroughly understand the different concepts of Health transition.
To learn the different theories and their modifications given to explain the transition in health.
To understand the transition models and also the exceptions to the theories of transition.
To be able to aware of the double and triple burden of diseases and will be able to understand mortality patterns associated.

Introduction to Health Transition

Health transition is the changes taking place over a period of time in a society’s health status. It covers all the aspects of a society health including its positive condition, illness and death. The health status of a society can be determined on the basis of their cultural, social and behavioural factors. Transition perhaps is deciphered as a change in the pool of diseases existing in a particular population as it undergoes westernization which accounts for an increase in the lifespan and reduction in the death, caused due to any kind of infectious disease, cancer, diabetes, cardiovascular diseases etc.

With the increase in the complexity and fast and vast transformation in every single aspect of living life, health is affected. These demographic and epidemiological changes pertains to prominent growth in the number and proportion of middle aged and elderly persons and the incidence of diseases occurring in this age groups.

Theories given for Health Transition

Malthusian Theory:

The theory pointing towards the transition in a population was first described by Thomas Robert Malthus, an economist. He articulated his views in his famous book “Essay on the Principles of population” (1798).

The principle behind Malthusian theory says that “human populations grow exponentially” while the production of food grows at an arithmetic rate. This can be interpreted as the number of human population doubles after every cycle (1, 2, 4, 8, 16…..) while the food production grows by the repeated addition of a uniform increment in each uniform interval of time (1, 2, 3, 4, 5, 6, 7…….). If the population will grow at an exponential rate then arithmetic food production will not be able to meet the growing food demands of the population. Malthus thus urged to control over the population growth in order to avoid this catastrophe.

To keep a check on the population growth, Malthus was never in support of birth control within a marriage and he has never talked about restricting the number of children in a family. The reason for opposing the birth control method was perhaps the awareness Malthus had about the problems that might arise from the delay or postponement of marriage.

Neo- Malthusian theory

The theory talks about favouring birth control and in particular perspective on the effects of population on human conduct and behaviour. The term ‘Neo- Malthusianism’ was first described by Dr. Samuel Van Houten in 1877. This theory unlike Malthusian theory put emphasis on use of contraception, abortion and also identified the working class with a problem of overpopulation. The reasons for birth control were different for poor and rich people of the society. The assumption was that availability of resources would give the poor little reason to abstain from having more children. The elite, threatened by the growing numbers of commoners, considered birth control as an important means of checking future conflict over their property. Neo- Malthusianism thereby reinforced the ideology of private property, individualism and capitalism. Social terms like “family planning” or Planned Parenthood were majorly used and birth control measures popularised as the emphasis was given more on spacing of children and women’s health.

Theory of Epidemiological transition

The theory of epidemiological transition was given by Abdel Omran in 1971[i]. It defines the transition or shift from a pattern of prevalent infectious diseases associated with malnutrition, famine and adverse environmental conditions to a pattern of prevalent chronic and degenerative diseases associated with urban and industrial life styles. The theory focuses on changing patterns of morbidity and mortality and it is thought to be evolved from a predominance of acute and infectious diseases to a predominance of chronic and degenerative diseases[ii].

Theory of epidemiological transition is classified into three phases:

a) Age of pestilence and famine: High and fluctuating mortality, with low and variable life expectancy ranging between 20 and 40 years. Causes of death include wars, famine, epidemic outbreaks etc. According to Armelagos[iii]., the transitions were a result of the transformation from hunter-gatherer societies, with more settled life required in order to tend cultivated crops and domesticated animals.

b) Age of receding pandemics: Mortality progressively declines and life expectancy rises considerably from under 30 to over 50 years. Population growth sustained and begins to be exponential.

c) Age of degenerative and man-made diseases: Here mortality continues to decline and eventually approaches stability at a relatively low level. The disappearance of infectious diseases increases the visibility of degenerative (cancer, cardiovascular diseases etc) and man- made (smoking, alcoholism, accidents etc) diseases.

The epidemiological transition is a result of process of modernization of a country from developing nation to developed nation status. Developments of modern healthcare, and medical interventions like antibiotics, drastically reduces infant mortality rates and extends average life expectancy which, coupled with subsequent decline in fertility rates, reflects a shift to chronic and degenerative diseases as more prominent causes of death.

Omran gave three factors to encourage the reduced fertility rates[iv]:

Bio-physiologic factors: these factors are associated with reduced infant mortality and expectation of longer life in parents.
Socioeconomic factors: are associated with survival during childhood and the economic perception as regards large family size.
Psychological or emotional factors: Based on the qualitative aspects of child raising, the society as a whole changes its opinion on family size and parental energies are redirected to the child raising.

Transition Models:

There are three basic models of epidemiological transition based on the peculiar variations in the pattern, the pace, the determinants and the consequences of population change.

1. The Classic/ Western model: This model defines as the gradual and progressive transition from high mortality (above 30 per 1000 population) and high fertility (above 40 per 1000) to low mortality (less than 10 per 1000) and low fertility (less than 20 per 1000).

Primary determinants of this transition model are;

a) Socioeconomic factors

b) Exponential population growth and

c) Sustained economic development

In the second and the third decades of the twentieth century, degenerative and manmade diseases seem to displace infections as the leading causes both for mortality and morbidity.

2. Accelerated epidemiological transition

The accelerated transition in the mortality is described by this particular model. This accelerated transition has occurred in few countries, notably in Japan. The time taken for mortality to reach 10 per 1000 level was found to be much shorter than the classical model. In this model, the shift to the age of degenerative and man- made diseases was very faster.

The accelerated rate of transition in most of the countries fitting in this model has been attributed to slow process of modernization prior to the drop in mortality in the 20th century, largely determined by medical and sanitary advances as well as by general social movements.

The countries favoured under the accelerated transition model followed a controlled rate of increase in population and also motivated the need to lower fertility in a relatively short period of time. For example, in Japan, the legalization of abortion has played a major role in the rapid fertility transition.

3. The contemporary/ delayed epidemiological transition model

This model is valid for most of the developing countries which are yet to be completed transition. The rates of mortality seems to be manipulated downward especially through public health measures leaving fertility at substantially high levels. This model is characterized by national and international programs of population control to fasten the fertility decline rates. Despite an improvement in the survival rates of women and children, infant and childhood mortality remains excessively high in most of these countries and females in their reproductive age groups continue to have higher mortality risks than males of the same age group.

Examples of the countries fitting in this model are; most countries in Latin America, Africa and Asia.

Modifications in the Theory of Epidemiological transition:

At first, Omran proposed a three stage theory of epidemiological transition (1971) to account for the extraordinary advances in health care made in industrialized countries since the 18th century. The “cardiovascular revolution” of the 1970s launched a new progress. The unexpected fall in death from man-made diseases particularly cardiovascular diseases was observed in some Western countries and this is described as Stage IV transition.

The fourth stage transition where the maximum point of convergence of life expectancies would seems to increase, was described by Olshansky and Ault (1986) as “age of delayed degenerative diseases” and by Rogers and Hackenberg (1987) as the “hybristic stage”.

The characteristics of the 4th stage defined by Olshansky and Ault are:

1. Rapidly declining death rates concentrated mostly at advanced ages

2. The age distribution is shifted progressively towards the older age.

3. Advances in medical technology, health care programs for the elderly

4. Reductions in risk factors at the population levels.

The “Hybristic stage” given by Rogers and Hackenberg (1987):

This stage was focussed on Omran’s hypothesis wherein the transition favors females over males, the young over the old and whites over non whites (in US). Rogers and Hackenberg disagreed with Olshansky and Ault in source of the change.

The term “Hybris” refers to excessive self confidence or a belief of invincibility. Mortality and morbidity is affected by man- made diseases, individual behaviour and potentially distractive lifestyles. Individual behaviour includes physical inactivity, unhealthy diet, excessive drinking and cigarette smoking. The destructive lifestyle practices include sexual orientation and social pathologies like accidents, homicides and HIV/AIDS.

Fifth stage: introduced by Olshansky and his colleagues;

The emergence of infectious diseases is the fifth stage of the epidemiological transition. A significant number of novel infectious and parasitic diseases (IPDs) have recently emerged. These IPDs had a profound effect on human mortality and will continue to have this impact on human health in the future[v].

Mortality Concepts and Patterns

The number of deaths by place, time and cause defines Mortality data. The data given by WHO on mortality reflect the deaths registered by National civil registration systems of deaths with the underlying cause of death. The Underlying cause of death is defined as the disease or injury which initiated the sequel of morbid events leading to death, or the circumstances of the accident or violence which produced the fatal injury in accordance with the rules of the International classification of diseases. Baseline mortality is the normal mortality level in a given population. Epidemiologists refer to a return to baseline level which indicates a stabilization of the situation and potential end to the mortality crisis.

The mortality levels and patterns around the world are quite diverse and increasing at an alarming rate. Omran has highlighted the rationale for the historical mortality changes. The level of mortality was found to be high in all the human populations until the 18th century with crude death rate to be around 40 per 1000 population i.e. more or less equivalent to the birth rate. Crude death rate is obtained by dividing the number of deaths in one calendar year by the total mean population of the same year and it not only depends on the level of mortality but also on the age patterns of the population. Since the mortality risks are much higher for old people than for younger people, same mortality risk will give a higher crude death rate in a population with more proportion of old people. The life expectancy until the eighteenth century hardly exceeded 25 years wherein approximately half of all newborns died before the age of five and even 30% before the age of one. To understand this, infant mortality rates are calculated by dividing the number of deaths less than one year of age observed during one year by the number of births in the same year[vi].

The estimates for mortality can be highly inaccurate but are often better and more easily captured than other indicators of health, which may be subject to different definitions and cultural interpretations.

Exceptions to the Theories of Transition:

The general trend of increasing life expectancy has got numerous exceptions.

a) Re-emergence of East- West Divergence: The fourth phase yet to begin

The life expectancy of several developed countries had reached a threshold of about 70 years of age (towards the end of 1950s). The “Cardiovascular revolution” in the policy making and treatment of CVDs has raised the life expectancy even more in these countries (towards the end of 1960s). However, few countries were not able to enter this new phase of health transition i.e. the fourth stage and hence are at exceptions.

Fig.1: Life expectancy trends since the 1930s: East- West convergence and divergence

The earlier trend of life expectancy continued up until the early 1990s, followed by the beginning of a decisive improvement. However, countries of former USSR, life expectancy trends began to fluctuate strongly in 1985. Life expectancy for males suddenly began to increase due to the Mikhail Gorbachev’s anti- alcohol campaign (1985-87), but the life expectancy rate soon fell back to its level of 1950 due to lack of efficient follow up measures and economic and social crisis. Further, as per the age specific mortality structure, a significant excess mortality is observed between the ages of 25 and 55 years.

There were also differences found in the mortality due to CVDs. In the early 70s, western countries like UK and France were successfully overcoming CVDs while the eastern countries like Poland and Russia were not able to do the same (Fig. 2). Further, there has also been increase in the man-made diseases (alcoholism, smoking, violence, particularly suicides, homicides etc) that has found to be deteriorating the health situation.

Fig. 2. Comparative trends of the standardized mortality rate due to cardiovascular diseases since 1950 in two Eastern European and two Western European countries [source: www. Cairn-int.info]

8. Global Burden of Disease:

There were very few diseases known at the beginning but with the advent in modern medical research, a wide range of diseases were discovered. When modern medicine succeeds in saving marginal lives, it automatically increases the biological burden of morbidity and disability in low mortality populations [vii].

The growing diversity of illness affecting the health transition has been a concern in both the developed and developing nations. There has been addition of some new disabling diseases like stress, depression, alcoholism and drug addiction. Both the conditions of stress and depression seem to increase the probability of dying from chronic diseases like heart failure or cancer.

Impact of Health Transition in Developed and Developing Nations:

There is a huge difference between the developed and developing nations status of health transitions. On one hand the developed nations are in their fourth stage of transition and likely in the fifth stage of transition but on other hand the developing nations are still in the infancy stages of health transition.

Double Burden of Disease:

As per the WHO, 2012 report, the non communicable diseases such as heart diseases, stroke, diabetes and cancer, now make up two thirds of all deaths globally, due to the ageing population and the spread of risk factors associated with globalization and urbanization. The control of risk factors such as tobacco use, sedentary lifestyle, unhealthy diet and excessive alcohol consumption becomes critical. Lifestyle and behaviour are linked to 20-25% of the global burden of disease. There will be dramatic changes and transitions in the world’s health needs, as a result of epidemiological transition in the next two decades.

As per the statistical health report of UN (2011), an increasing number of countries face a double burden of disease as the prevalence of risk factors for chronic diseases such as diabetes, heart diseases and cancers increase and nations are still struggling to reduce the maternal and child deaths caused by infectious diseases. It is quite evident that no country in the world can address health from either an infectious disease perspective or a non communicable disease one. There is a need to develop a health system that can address the full range of the health threats in both areas. Non communicable diseases are expected to account for seven out of every ten deaths in the developing regions by the year 2020 and infectious diseases seem to be the foremost cause of ill health. There is also evidence that the poorest in developing countries face a triple burden of disease: communicable diseases, NCDs and socio- behavioural illness.

The interactions between communicable and non communicable diseases are poorly understood. For example, low birth weight (LBW) which is often caused as a result of maternal infections and malnutrition and is a known risk factor for child mortality. Increasing evidence have clearly shown that LBW programs which are aimed at increasing the birth weight increases the risk for common non communicable diseases such as type 2 diabetes, hypertension, cardiovascular disease and metabolic syndrome.

The preventive programs in the developing nations are educational, cultural, economic and climatic factors affecting the preventive strategies. However, the programs in the developed nations were focussed on the promotion of cessation of smoking, physical inactivity and a healthy diet. All these strategies in the developing and developed nations are bound with a culture specific perception. The government is required to take some strong steps regarding solutions to the medical care problems in their countries.

Summary

The module highlights the different concepts of health transition. The health status of a society can be determined on the basis of their cultural, social and behavioural factors. With the increase in the complexity and fast and vast transformation in every single aspect of living life, health is affected. There are different theories given to explain health transition e.g. Malthusian theory, Neo-Malthusian theory and theory of epidemiological transition. The epidemiological transition is a result of process of modernization of a country from developing nation to developed nation status. Developments of modern healthcare, and medical interventions like antibiotics, drastically reduces infant mortality rates and extends average life expectancy which, coupled with subsequent decline in fertility rates, reflects a shift to chronic and degenerative diseases as more prominent causes of death.

There are three basic models of epidemiological transition based on the peculiar variations in the pattern, the pace, the determinants and the consequences of population change. The module also highlights the mortality concepts and the patterns associated with it. Epidemiologists refer to a return to baseline level which indicates a stabilization of the situation and potential end to the mortality crisis. The mortality levels and patterns around the world are quite diverse and increasing at an alarming rate. Omran has highlighted the rationale for the historical mortality changes.

References

[i] Omran AR. The Epidemiologic Transition. Milbank Mem Fund Q. 1971;49:509–538.

[ii]Rogers, R. G., & Hackenberg, R. (1987). Extending epidemiologic transition theory: a new stage. Social biology, 34(3-4), 234-243.

[iii] Armelagos GJ, Brown PJ, Turner B. Evolutionary, historical and political economic perspectives on health and disease. Soc Sci Med. 2005;61:755–765.

[iv] Omran, A. R. (2005). The epidemiologic transition: a theory of the epidemiology of population change. The Milbank Quarterly, 83(4), 731-757.

[v] Olshansky, S. J., Carnes, B. A., Rogers, R. G., & Smith, L. (1998). Emerging infectious diseases: the fifth stage of the epidemiologic transition?. World Health Statistics Quarterly, 51(2-4), 207-17.

[vi]Meslé, F., & Vallin, J. (2010). Mortality patterns and their implications. Demography-Volume I, 185.

[vii] Gruenberg, E. M. (1977). The failures of success. The Milbank Memorial Fund Quarterly. Health and Society, 3-24.

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