introduction to daly and burden of disease
DESCRIPTION
This is a simple introduction to disability adjusted life years and global burden of diseaseTRANSCRIPT
Burden of Disease: Introduction
Arindam BasuSchool of Health Sciences,University of Canterbury,
[email protected] 24, 2014
Part I: DALY AS A SINGLE GAP BASED MEASURE OF POPULATION HEALTH
Health
BIRTH DEATH
STATE of WELL-BEING
Health
BIRTH DEATH
Physical, Mental, Social WELL-BEING
Concept of Physical, Mental, Social
PHYSICAL
MENTAL
SOCIAL
0
1
1
10 = DEATH1 = FULL LIFE
Metaphor of Life
(1,1,1)
Health
BIRTH DEATH
Complete Physical, Mental, Social WELL-BEING
“And so from hour to hour, we ripe and ripe, and from hour to hour, we rot and rot; and
thereby hangs a tale” -Shakespeare
Health As a “STATE”
WATER AS A METAPHOR OF HEALTH and CHANGE of STATE
Image source: Wikimedia commons
Health
BIRTH DEATH
State of Complete Physical, Mental, Social WELL-BEING
What Is Absence of Health? Disease? Infirmity?
What is Absence of Disease?Health?
Health
BIRTH DEATH
“State of Complete Physical, Mental, Social WELL-BEING, not merely absence of disease or infirmty”
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)
“Health is Wealth” (Ancient Saying)
Provocation: “Is Health Resource? Or is Health Merely a “State of Existence”? Or Both? How do we reconcile?
Context of Measuring Health
PATIENTS
PAYERSPROVIDERS
MANAGERS
Different Perspectives of Measuring Health
PATIENTS
PAYERSPROVIDERS
MANAGERS
“A Case of Fever That Requires Admission in a Ward”
What is my Quality of Life?
What is the Temperature? “How Much Did it Cost?
“How Long Did the Patient Stay? (LoS)”
Constraints and Limitations of a Summary Measure of Health
The Measure Must Be
Consistent
The Measure Must Be Comparable and
Make Sense
“ONE MEASURE TO RULE THEM ALL”
The Principle
“May You Live a Long Life in Good Health”!
Health Gap
The Ideal: Individuals Live Standard Life Expectancy At Full Length
Health Gap: State of Population Health Compared to a Normative Goal
YEARS of LIFE LOST (YLL)
Natural Death at Age 86 years
He Dies at the Age of 50 Years Due to Road Traffic Injury
This person has therefore lost 86-50 = 36 YEARS of HEALTHY LIFE
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)
YEARS Lived with Disability (YLD)
Natural Death at Age 86 years
He suffers RTI at the Age of 50 Years and LIVES with 50% Disability
This person has therefore lost (86-50) * 0.5 = 18 YEARS of HEALTHY LIFE
YLD for Populations
Age-Specific Prevalence of the Disease or Sequela
Multiplied By
Age-Specific Disability Weight
DALY = YLL + YLD
… AND ONE FORMULA To RULE THEM ALL …
PART II: ESTIMATE GLOBAL BURDEN OF DISEASE USING DALY
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
Chris Murray (L) and Alan Lopez (right) considered to be the “grand fathers” of the Global Burden of Disease Approach
World
• Data from– 187 Countries– 21 Regions
• Basis:– Geographical
Contiguity– Epidemiological
Homogeneity
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
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
Steps of YLL Estimation
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
Estimation of YLD
• Prevalence of Sequela * Disability Weight
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
DALYs For Males, GBD 2010
AGE-WISE DISTRIBUTION of DALYs, Women, GBD 2010
Change in the DALYs Between 1990 - 2010
Let’s Start Playing with the Data:
http://www.healthmetricsandevaluation.org/gbd/visualizations/gbd-insight