1. How can we measure disease
at the global level?
(Global Burden of Disease)
1
Assistant professor Dr. Seo Ah Hong
ASEAN Institute for Health Development

2. Health of individuals

3. Health of a population

4. Epidemiological Tools
• Mortality: IMR, MMR
• Morbidity (Prevalence, incidence)
• Life expectancy
• Disability-Adjusted Life Year (DALYs)
4

5. Life expectancy

6. Life expectancy
• The average number of years of life at a given age in a population if
the current mortality experience were to continue
• “at a given age”; So, it varies by age
• Life expectancy at birth
• The average number of years a new-born baby could expect to live if current
trends in mortality were to continue for the rest of the new-born's life
• How long they will live if conditions remain as in a country in a
specific year during their whole lifetime?
6

7. 20 000 $2000 $200 $
Income per person (comparable dollars per year)
10
0
8
0
6
0
4
0
2
0
0
Lifeexpectancy(years)
1000
100
1
Population
(millions)
50 years
Burundi
81 years
Sweden
GAPMINDER
7
This came from Gapminder (http://www.gapminder.org/data/).

8. 10
0
8
0
6
0
4
0
2
0
0
Age(years)
SarahAnnJeanLizPierre
84
72
57
36
1
GAPMINDER
8
This came from Gapminder (http://www.gapminder.org/data/).

9. 10
0
8
0
6
0
4
0
2
0
0
Age(years)
SarahAnnJeanLizPierre
84
72
57
36
1
50 years
Calculate the mean…
1+36+57+72+84
5
= 50
GAPMINDER
9
Life
Expectancy
This came from Gapminder (http://www.gapminder.org/data/).

10. 10
0
8
0
6
0
4
0
2
0
0
Age(years)
SarahAnnJeanLizPierre
84
72
57
36
1
child
adult
old
So yes, 2 of 5
get old in Burundi
GAPMINDER
10
This came from Gapminder (http://www.gapminder.org/data/).

11. 10
0
8
0
6
0
4
0
2
0
0
Age(years)
SaraAntonJanLisaPer
How long will
they live…
…if conditions remain as in
Sweden in 2007
during their whole lifetime?
GAPMINDER
11
This came from Gapminder (http://www.gapminder.org/data/).

12. 10
0
8
0
6
0
4
0
2
0
0
93
Age(years)
SaraAntonJanLisaPer
63
77 84 88
63+77+84+88+93
5
=81
81 years
Calculate the mean…
GAPMINDER
12
This came from Gapminder (http://www.gapminder.org/data/).

13. Question
• The life expectancy is 31 years higher in Sweden (81 years) than in
Burundi (50 years). Why?
① Is it because all Swedes live 31 years longer than all Burundians?
② Is it because some Swedes live much longer than all Burundians?

14. 10
0
8
0
6
0
4
0
2
0
0
Age(years)
But “dying young” in Sweden
is very different
from “dying young” in Burundi
“To live long” in Sweden
is almost the same as
“to live long” in Burundi
GAPMINDER
14
This came from Gapminder.

15. Question
• The life expectancy is 31 years higher in Sweden (81 years) than in
Burundi (50 years). Why?
① Is it because all Swedes live 31 years longer than all Burundians?
② Is it because some Swedes live much longer than all Burundians?

16. Summary of Life expectancy
1) Life expectancy is an average
:Most Burundi people get older than 65 years and
some die in childhood.
2) Life expectancy is low when child
deaths are common
:It is low in Burundi not because all die a bit earlier,
but because some die much younger
16

17. Do we need other estimates of disease
burden?
Due to the rise in importance of chronic diseases as
the leading cause of death, along with growing
numbers of the very old,
Both mortality rates and life expectancy are useful,
but
They do not tell us anything about disease burden in
people living with diseases
17

18. Global Burden of Disease(GBD)
• The GBD study is a collaboration between the WHO,
the World Bank and the Harvard School of Public
Health.
• The concept was firstly published in 1996.
• It attempts to estimate the total burden due to
diseases.
• Constituting the most comprehensive and
consistent set of estimates of mortality and
morbidity yet produced.
18

19. Disability-Adjusted Life Years (DALYs)
•A single indicator of total disease burden
•Combining information about mortality
and morbidity in a single number.
•Internationally accepted measure of
death and disability
•Increasingly cited as a powerful tool for
decision makers in international health.
19

20. Disability-Adjusted Life Years (DALYs)
Interpretation: One DALY = one lost year of healthy life
Ideal health
Current health DALY

21. All deaths are equal?
• “Premature” death deserves special attention
• Years of Life Lost (YLL) due to premature death
21
YLL= N X L
N = number of deaths
L = standard life expectancy at age of death in years

22. Death is not the only thing that matters
Years of healthy life Lost due to Disability (YLD)
22
YLD= I x L x DW
I = number of incident disability cases
L = average duration of the case until remission or death (years)
DW = disability weight
(the severity of the disease:0 (perfect health) to 1 (dead))

23. Disability-Adjusted Life Year
(DALY)
Facilitate comparisons of different health states or
health outcomes.
•Compare the health of one population with another – and
allow decision makers to focus on health systems with the
worst performance
•Compare the health of the same population at different
points in time
•Compare the health of subgroups within a population - to
identify health inequalities
23

24. Disability-Adjusted Life Year
(DALY)
Facilitate comparisons of different health
states or health outcomes.
=> DALYs help to inform debates on
priorities for health service delivery,
research and planning.
24

25. •Disease burden can be attributed to
• specific diseases (e.g. HIV, TB, obesity,
diabetes) and
• risk factors for ill health (unsafe sex,
overcrowding, smoking, excess cholesterol,
low FV).
25

26. Christopher JLM, and Alan DL. N Engl J Med 2013;369:448-57

27. Christopher JLM, and Alan DL. N Engl J Med 2013;369:448-57

28. Why are DALYs important?
• Allows to address PREVENTABLE DISEASES in each region of the world
- how much of risks to health could be avoided in future years.
• DALYs attempt to provide an appropriate, balanced attention to the
effects of non-fatal as well as fatal diseases on overall health.
28

29. Summary of
Disability-Adjusted Life Year (DALY)
• The sum of years of life lost and years of life lived
with disability.
• A summary measure of overall disease burden in
a population, combining mortality and disability.
• Measuring a health gap, relative to an “ideal” life
expectancy
• Currently the best indicators available now to set
priorities for resource allocation.

30. Thank you for your attention!!!
Three Questions are following^^

31. The life expectancy at birth in Burundi is 50 years
Question 1: What is correct?
(1) We will rarely see elderly people (>65) in Burundi
(2) We will still see a bunch of elderly people in Burundi
31

32. The life expectancy at birth in Sweden is 81 years
The life expectancy at birth in Burundi is 50 years
Question 2: So, do most Swedes live 31 years longer
than Burundian?
(1) Yes
(2) No
32

33. Question 3: Mark the following statements as either true or
false on your answer sheet.
Q
u
i
z
1
33
Question True False
1 Life expectancy at birth is strongly
associated with mortality in childhood.
O O
2 DALYs capture the number of healthy
years lost to disability only.
O O
3 The calculation of DALYs involves an
index of the disability attributed to
specific diseases
O O