This is a simple introduction to disability adjusted life years and global burden of disease

1. Burden of Disease: Introduction
Arindam Basu
School of Health Sciences,
University of Canterbury,
arindam.basu@canterbury.ac.nz
February 24, 2014

2. Part I: DALY AS A SINGLE GAP BASED
MEASURE OF POPULATION HEALTH

3. Health
STATE of WELL-BEING
BIRTH
DEATH

4. Health
Physical, Mental, Social
WELL-BEING
BIRTH
DEATH

5. Concept of Physical, Mental, Social
Metaphor of Life
1
(1,1,1)
SOCIAL
1
PHYSICAL
0
MENTAL
1
0 = DEATH
1 = FULL LIFE

6. Health
Complete Physical, Mental, Social
WELL-BEING
BIRTH
DEATH

8. Health As a “STATE”
WATER AS A
METAPHOR OF
HEALTH and
CHANGE of STATE
Image source: Wikimedia commons

9. Health
State of Complete Physical, Mental, Social
WELL-BEING
BIRTH
DEATH

10. What Is Absence of Health?
Disease? Infirmity?
What is Absence of Disease?
Health?

11. Health
“State of Complete Physical, Mental, Social
WELL-BEING, not merely absence of disease or
infirmty”
BIRTH
DEATH
Preamble to the Constitution of the World Health Organization as adopted by the
International Health Conference, New York, 19-22 June, 1946; signed on 22 July 1946 by
the representatives of 61 States (Official Records of the World Health Organization, no. 2, p.
100) and entered into force on 7 April 1948.
The Definition has not been amended since 1948.
(http://who.int/about/definition/en/print.html)

12. “Health is Wealth” (Ancient Saying)

13. Provocation: “Is Health Resource? Or is
Health Merely a “State of Existence”?
Or Both? How do we reconcile?

15. Context of Measuring Health
PATIENTS
PAYERS
PROVIDERS
MANAGERS

16. Different Perspectives of Measuring Health
What is my Quality of Life?
PATIENTS
What is the Temperature?
PROVIDERS
“A Case of Fever
That Requires
Admission in a
Ward”
“How Much Did it Cost?
PAYERS
MANAGERS
“How Long Did the Patient Stay? (LoS)”

17. Constraints and Limitations of a
Summary Measure of Health
The Measure
Must Be
Consistent
The Measure Must
Be Comparable and
Make Sense

18. “ONE MEASURE TO RULE THEM ALL”

19. The Principle
“May You Live a Long Life
in Good Health”!

20. Health Gap
The Ideal: Individuals Live
Standard Life Expectancy
At Full Length
Health Gap: State of
Population Health
Compared to a Normative
Goal

21. YEARS of LIFE LOST (YLL)
This person has therefore
lost 86-50 = 36 YEARS of
HEALTHY LIFE
He Dies at the
Age of 50 Years
Due to Road
Traffic Injury
Natural
Death at
Age 86
years

22. Concept: YLL for Populations
Number of Deaths in the Population for An Age Group
Multiplied By
Life Expectancy At Birth for that Age (~ 86 – Age in Years)

23. YEARS Lived with Disability (YLD)
This person has therefore
lost (86-50) * 0.5 = 18
YEARS of HEALTHY LIFE
He suffers RTI
at the Age of
50 Years and
LIVES with 50%
Disability
Natural
Death at
Age 86
years

24. YLD for Populations
Age-Specific Prevalence of the Disease or Sequela
Multiplied By
Age-Specific Disability Weight

25. … AND ONE FORMULA To RULE THEM ALL …
DALY = YLL + YLD

26. PART II: ESTIMATE GLOBAL BURDEN OF DISEASE USING DALY

27. Global Burden of Disease Approach
•
•
•
•
•
•
•
•
•
Chris Murray (L) and Alan Lopez (right)
considered to be the “grand fathers” of
the Global Burden of Disease Approach
Initiated by World Bank (1990s)
Now Seven Organizations:
IHME
Imperial College
University of Queensland
Johns Hopkins
University of Tokyo
WHO
Data from 187 countries, 291
conditions, 1160 sequela, 220
disease states
• Synthesis of Epidemiological Data

29. World
• Data from
– 187 Countries
– 21 Regions
• Basis:
– Geographical
Contiguity
– Epidemiological
Homogeneity

30. Diseases
• 291 Diseases into 5
Levels of Hierarchy
• (4 Levels + 1 Health
State)
• 1160 Sequelae
• Common Sequelae are
termed as “Health
States” – 220 health
states
• 69 Risk Factors

31. Steps of YLL Estimation
New Normative Standard Life
Table Was Used for males and
females to compute YLL at each
age by identifying lowest
observed death rates for any age
group in countries with > 5 million
population

32. YLL Estimation
• Number of Deaths * Life Expectancy at Each Age Band
• Count Total # Deaths in a Year and Assign Unique Cause
• Number of Deaths Come From:
–
–
–
–
–
–
Vital Registration Systems
Mortality Surveillance Systems
Census
Surveys
Hospital and Police Records
Verbal Autopsies and Data from Mortuary
• Life Expectancy at Each Age Band is Maximized and is
set at ~ 86 years for Males and Females

33. Estimation of YLD
• Prevalence of Sequela * Disability Weight

34. Sequelae
DISEASES in HIERARCHY
Diseases Lead to
Specific
Conditions, known as
Sequelae (singular:
Sequela)
Many Diseases Have Multiple
Sequelae which are grouped
under “Health States”, such as
Anemia due to Malaria and
Dengue, has been classified
into mild, moderate, and
severe Anemia. These are
estimated as well

38. DALYs For Males, GBD 2010

39. AGE-WISE DISTRIBUTION of DALYs, Women, GBD 2010

40. Change in the DALYs Between 1990 - 2010

42. Let’s Start Playing with the Data:
http://www.healthmetricsandevaluation.org/gbd/visualizations/g
bd-insight