Syllabus - Demography

Contents
The aging of society
Health and the aging of society
Delaying illness, prolonging life
Life prolonged, disability increased?

The aging of society

Society is aging:

  • The process was first reported in France in the 1830s, as the result of declining birth rates
  • In the 20th century the effect was augmented by gains in life expectancy in the industrialized nations.

There are more older people, with, at the end of the last (20th) century:

  • An overall world-wide population growth rate of only 1.6% per year due to a reduction in fecundity and fertility
  • An increase in the numbers of older people of 2.8% per year world-wide.

In the Americas, the growth rate of the 60+ age group is expected to be 3.5 times that of the total population by 2010.

The consequence is an ageing society, with a proportionately high (and increasing) number of older people.
Projected percentage increase in populations aged 65 and over, 1994-2020
(Butler, RN. Population aging and health. Brit Med J 1997; 315: 1082-1084)

This combination of a shift from high to low mortality and high to low fertility, which results in population aging, is called the "demographic transition". But society is aging at a different rate in different countries.
Many people in developing countries still live in poverty but are less likely to die than in the past, because of medical intervention. Fertility rates have also been reduced by worldwide adoption of modern contraception. So the demographic transition to an older population is a worldwide phenomenon.
The demographic transition to an older population is a worldwide phenomenon

Demographic transition in developing and developed countries

FEATURE DEVELOPED COUNTRIES DEVELOPING COUNTRIES
Speed of development Slow, over a century Fast, over decades
Timing Already occurred Occurring
Main cause Consequences of the Industrial revolution Medical intervention

The greatest differences are between the developed and developing countries. A simple index which illustrates the differences between countries is:
the number of people aged 60 / the number of people aged under 15

In 1997, this index was 82 in Canada and 9 in Nicaragua, illustrating the discrepancies between nations. However, the shift to an older society in the developing nations is expected to catch up with that of the developed countries.
Population pyramids in different parts of the world. By the year 2030, most countries are expected to have a similar age structure.
Population pyramid - Asia (1995 and 2025)


Population pyramid - Latin America (1995 and 2025)

Population pyramid - Europe (1995 and 2025)

Not only are there more old people but there has been an increase in the old-old. In the last century:

  • Average life expectancy from birth increased by more than 25 years
  • Five of those years have been added to average life expectancy from base age 65.

Not only are there more old people, but there is an increase in the old-old.
Percentage of population aged 80 and over, 1994 and 2020
(Butler, RN. Population aging and health. Brit Med J 1997; 315: 1082-1084)

The increases in life expectancy vary geographically.

Life expectancy in different countries. In most parts of the world, women tend to live longer than men do. However, in the western world the gender gap is narrowing.
(Marsden,K. The Five percent Solution. Centre for Policy Studies, London, 2000)

COUNTRY LIFE EXPECTANCY (years)
At birth At 60 years (men) At 60 years (women)
Japan 80 - -
Canada 79 - -
France 78 19.9 25.1
Italy 78 19.5 24.0
Germany 77 18.8 23.1
United Kingdom 77 18.8 22.5
USA 76 18.8 22.5
Lower and middle income countries 65 - -
World 67 - -

Although people in developing countries do not live as long, there are many more old people in them:
  • In 1980 they accounted for over half of all people aged 60+ worldwide
  • By the end of the 20th century, the figure was 60%
  • This is expected to rise to 80% towards the middle of this century.

By 2025, China may have 285 million people aged over 60 years - more than the total present population of the US.
Although people in developing countries do not live as long, there are many more of them


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Health and the aging of society

Aging is accompanied by physiological changes and illnesses:

  • Aging-dependent changes (normal aging) (see the dedicated section on Physiology: Age-related physiological change)
  • Aging-associated changes (pathological aging).

Special medical features of illness in old age
FEATURES OF THE ILLNESS
Insidious onset (a slow reduction of function may be wrongly accepted as an inevitable part of aging)
Multiple pathology. Failure in one system may lead to failure in another a cascade effect. No one disease dominates the clinical picture
Multiple organ failure
Multiple causes of the same symptom. Symptoms which are common to a number of diseases of old age are confusion, falls, incontinence, immobility. These have been called the Geriatric Giants
Chronic incurable diseases more common than in younger people (leading to the epidemiological transition, see below)
FEATURES OF PRESENTATION AND DIAGNOSIS
Late presentation (the Iceberg phenomenon, see below)
Presentation with a social problem which may obscure an underlying disease or complicate its management
Intellectual failure and inability to communicate may complicate history-taking, diagnosis and management
Different presentation to the young. For example:
Multiple factors combine to produce atypical presentation
Old people seem less sensitive to visceral than articular pain
Reduced response of the reticulo-endothelial system, so that leukocytosis and lymphadenopathy are less evident in infections
FEATURES OF MANAGEMENT
Multiple drug use which may complicate management
Some drugs cause as well as cure health problems and this may be critical in older people
The geriatric giants

Epidemiological transition
Younger people are most likely to die from infections and acute conditions and older people are most likely to die from chronic and degenerative illnesses and their complications. Therefore the aging of society means that in the population as a whole there is a relative increase in the importance of chronic and degenerative illnesses and their complications as a cause of death. This increase is called the epidemiological transition.
There is a change from infections and acute conditions to chronic and degenerative illness as the leading causes of death as a population ages

The iceberg phenomenon
Older people use healthcare services more than younger people. But most are moderate users and only a few are frequent consulters. Hospital care accounts for most of the healthcare expenditure in the old as in the young. This is even though many medical conditions common in older age are chronic rather than acute emergency problems.
Older people tend to under-report medical and social problems (the iceberg phenomenon), for many reasons, including:

  • Fear of hospitalization
  • Fear of unpleasant investigations
  • Fear of treatment
  • Risk of involuntary removal to residential care
  • Lack of information
  • Imagining that symptoms are not amenable to treatment
  • Low health expectations
  • Failure to recognize the problem.

Older people tend to under-report medical and social problems (the iceberg phenomenon)


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Delaying illness, prolonging life

The changes and conditions that accompany old age are seldom apparent before middle age, but then their incidence doubles exponentially every 5 years or so.
It follows that if the onset or progression of these conditions were delayed by five years, there would be one less exponential doubling in life. This would have the effect of halving the incidence of these conditions in older people. The end result should be:

  • Delay in death from these conditions or their complications (which should result in longer life spans)
  • A delay/reduction in the development of multiple morbidity states (which increase frailty and dependency)
  • Healthier aging.

Age-related conditions may be delayed by the same factors that increase lifespan:
  • A better diet and lifestyle (which can be related, among other health advantages, to a lower rate of infectious diseases)
  • Modern sanitation, less overcrowding, and improved living conditions generally
  • Medical advances, from immunizations and antibiotics to the latest developments
  • Provision of, and access to, good healthcare
  • Socioeconomic advances (e.g. the availability of pension funds and other provisions for older people).

Age-related conditions may be delayed by the same factors that increase lifespan

Geographical variations in these factors mean that death rates from specific causes vary with country.
Chances per 1000 at age 65 of eventually dying from a specified cause. The differences in risk seen in this table are caused by differences in the factors that can prolong health and lifespan, e.g. diet, access to good healthcare.
(Marsden, K. The Five percent Solution. Centre for Policy Studies, London, 2000)


The reduction in mortality from chronic diseases means that older people then become more likely to die from some other cause. It may also mean that there is increased morbidity and disability because of these conditions, if their incidence does not decrease.


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Life prolonged, disability increased?

How big is the increase in years of active life of a good quality?


There are three different theories about the impact on population health of the factors that lead to longer lifespans:
  • Shifting of mortality to older age groups has been achieved partly through medical interventions that prolong the time to death for chronic progressive diseases, rather than reducing their incidence or rate of progress. This results in an increased prevalence of disability and morbidity. Certainly, population surveys in France, Canada, Britain and the US show increases in the reported prevalence of chronic conditions
  • The same factors delay illness and increase lifespan. There is a natural limit to our lifespan of about 115 years. So further improvements in health will not result in a further decline in mortality, but will compress morbidity at the end of the life span. This may explain why reports from Japan, the United States and Europe show that people are healthier for longer
  • Morbidity and mortality are in dynamic equilibrium. This is consistent with the evidence that although overall levels of disability have increased, there is a decline in the most serious forms.

The types of condition that patients have that contribute to relative disability, according to a UK community practice survey. Their relative importance will be different in different countries. (Brocklehurst)

Causes of death in developing regions by year (Brocklehurst)

Number of chronically disabled Americans aged 65 and over, 1982-1986. This shows that not only are we living longer, we are healthier for longer.
(Butler, RN. Population aging and health. Brit Med J 1997; 315: 1082-1084)

Older women are more likely to be disabled than older men. Although the "active life expectancy" of women is longer, the expected period of terminal disability and dependency is about twice that for men.

We are unlikely to achieve our full natural lifespans because, with longer lifespans, there is:

  • A longer lifetime of exposure to various potentially toxic agents (not all of which may be known)
  • A problem of insufficient resources.

Therefore, healthcare workers will need to cope with increased pressure on health and social care resources.
The existence of more old people and more survivors of serious diseases has meant an increase in the incidence of morbidity and non-life-threatening but disabling chronic diseases and conditions


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