Global health trends and burden of disease

Question 1

» Some concepts from demography that are important for public health:

Answer 1

• Population growth
• Fertility rates (birth rates)
• Life expectancy (death rates)
• Age structures and population pyramids

Question 2

Population growth factors

Answer 2

» Fertility rates
- “Global fertility is projected to fall from 2.5 children per woman in 2019 to 2.2 in 2050.”
» Life expectancy
- “Life expectancy at birth is expected to rise from 72.6 years in 2019 to 77.1 years in 2050.”
» International migration
- “International migration is a much smaller component of population change than births or
deaths. However, in some countries and areas the impact of migration on population size is
signifcant.”

Question 2

Fertility rates by country

Answer 2

» Some countries have
fertility rates as high as 5
or 6 live births per woman
» Other countries have
fertility rates as low as 1.5
live births per woman

Question 2

Fertility rates

Answer 2

» In demography, fertility refers to the number of chldren that a woman has, rather than the
physical capability to produce chldren (which in demography is termed “fecundity”)
» The fertility rate is the number of children that a woman has, on average, in a given
population
» One metric that is used = “live births per woman”

Question 2

“Why do some countries have low fertility rates and other countries have high fertility rates?”

Factors affecting fertility rates

Answer 2

» The invention of, and access to, modern contraception
- e.g. oral pill, implants, intrauterine devices (IUDs), condoms
» Woman’s empowerment, including education, employment, household decision-making
» Child survival rates, which may afect a family’s decision to have more or fewer children

Question 3

Fertility rates by country

Answer 3

Question 4

Factors afecting life expectancy

Answer 4

» The invention of, and access to, life-saving medical technologies, pharmaceuticals, and
other forms of health care
» Quality of life, including…
- Nutrition and healthy diets
- Clean water, sanitation, and hygiene
- Exposure to other risk factors
» Child mortality rates

Question 5

Key points

Answer 5

» Understanding public health involves understanding demographic concepts such as
population growth, fertility rates, and life expectancy
» In some countries, fertility rates are very high (5 or 6 live births per woman) and the
population is still growing. In other countries, fertility rates are low (1.5 live births per
woman) and the population is no longer growing.
» Fertility rates and life expectancy are afected by similar factors, such as access to
contraception and health care, economic development, women’s empowerment, and quality
of life.
» For this reason, countries that have high fertility rates typically also have low life
expectancy; countries that have low fertility rates typically also have high life expectancy.

Question 5

World age structure over time

Answer 5

Question 5

Demographic transition photo

Answer 5

Question 6

Demographic transition

Answer 6

» We saw before that… - Most countries that have high fertility
rates also have low life expectancy
- Most countries that have low fertility also
have high life expectancy
» Over time, as countries have experienced
technological progress and economic
development, fertility rates have
decreased and life expectancy has
increased

Answer 7

Answer 7

“…the historical shift from high birth rates and high death rates in societies with minimal
technology, education (especially of women) and economic development, to low birth rates and
low death rates in societies with advanced technology, education and economic development”
~ Wikipedia, Demographic transition

Question 7

Age structures

Answer 7

» “Population pyramid”
» A representation of the age structure of a
population
» Horizontal bars show the proportion of the
population in diferent age categories
» Male and female on diferent sides
(usually)
» Youngest at bottom, oldest at top (usually)

Answer 8

» The demographic transition (the
shift from high birth rates and
high death rates, to low birth rates
and low death rates), results in
changes in age structures
(changing population pyramids)

Question 8

Overview 2B lecture slides

Answer 8

» Disease classifcation
» Burden of disease
» Epidemiological transition

Question 9

Key points

Answer 9

» Over time, as countries have experienced technological progress and economic
development, fertility rates have decreased and life expectancy has increased.
» This results in a shift in age structures, which is known as the “demographic transition”.
» Some countries (such as Australia) are in the late stages of the demographic transition and
now have low fertility rates and high life expectancy, and as a result, have an age structure
with as many older adults as younger children.
» Other countries (such as Mozambique) are in the early stages of the demographic transition
and still have high fertility rates and low life expectancy, and as a result, have an age
structure with more younger children than older adults.
» These changes in birth rates, death rates, and age structures are linked to many other
aspects of public health, including the prevalance of diferent diseases around the world.

Question 10

Disease classifcation

Answer 10

» It is useful to be able to talk about diferent types of diseases
» Several diferent disease classifcation systems
- Communicable / non-communicable / injury
- International Classifcation of Diseases (ICD-9, ICD-10, ICD-11)
- More detailed disease categories used by WHO, GBD, others

Question 11

Disease classifcation photo

Answer 11

Question 12

International Classifcation of Diseases (ICD-11)

Answer 12

“The international standard for systematic recording,
reporting, analysis, interpretation and comparison of
mortality and morbidity data.”
“…allows countries to count and identify their most
pressing health issues.”
~ World Health Organisation

Question 12

International Classifcation of Diseases (ICD-11) photo

Answer 12

Question 13

Australia, causes of death photo

Answer 13

Question 13

Key points

Answer 13

» We use disease classifcation systems to talk about diferent types of diseases
» One important classifcation is communicable vs non-communicable diseases (infectious vs
chronic diseases)

Question 14

Burden of disease over time, australia

Answer 14

Question 14

The burden of disease of diferent sub-populations. Australia, young children

Answer 14

Question 14

Diferent ways to look at it

Answer 14

» The burden of disease for a single country at a single point in time
» How the burden of disease is diferent for diferent sub-populations of a country
» How the burden of disease is diferent for diferent countries
» How the burden of disease has changed over time

Question 14

Burden of disease

Answer 14

» In every population, some diseases cause more death and disability than other diseases
» The way in which diferent diseases afect a country is refered to as a country’s “burden of
disease” (or disease burden)
» In other words, the burden of disease tells us…
- The relative impact of diferent diseases in a population
- Which diseases are responsible for the most death and disability

Question 15

Australia, teenagers/young adults

Answer 15

Question 15

The burden of disease of different countries

Answer 15

Question 16

Australia, older people

Answer 16

Question 17

The burden of disease of different countries

Answer 17

Question 18

Burden of disease over time, global

Answer 18

Question 19

Key points

Answer 19

» In every population, some diseases cause more death and disability than other diseases
» The way in which diferent diseases afect a country is refered to as a country’s burden of
disease (or disease burden)
» Diferent countries (and sub-populations) are afected by diferent diseases to diferent
degrees (i.e. diferent countries and sub-populations have diferent burdens of disease)
» In general…
- Most high-income countries have a burden of disease that is dominated by non-communicable diseases
- Most low-income countries have a burden of disease that includes both non-communicable diseases
and communicable diseases
» A country’s burden of disease can change over time

Question 20

Two transitions

Answer 20

» Demographic transition = change in age structures (population
pyramids)
» Epidemiological transition = change from communicable diseases
to non-communicable diseases (burden of disease)

Question 20

Epidemiological transition

Answer 20

“…the replacement of infectious diseases by chronic diseases over time due to increased life
span as a result of improved health care and disease prevention”
~ Wikipedia, Epidemiological transition

Answer 20

» Some countries (such as Australia) are in the late stages of the epidemiological transition
and now have a burden of disease that is dominated by non-communicable diseases
» Other countries (such as Mozambique) are in the early stages of the epidemiological
transition and still have a burden of disease that is dominated by communicable diseases

Question 21

Key points

Answer 21

» In general, over time, countries have moved from having a disease burden that is dominated
by communicable diseases to a disease burden that is dominated by non-communicable
diseases – this is called the epidemiological transition
» Some countries (such as Australia) are in the late stages of the epidemiological transition
and now have a burden of disease that is dominated by non-communicable diseases
» Other countries (such as Mozambique) are in the early stages of the epidemiological
transition and still have a burden of disease that is dominated by communicable diseases
» The reason for this transition is because, over time, with developments in medicine,
technology, access to health care, sanitation, and quality of life, we have been able to reduce
much of the death and disability caused by communicable diseases