Global Burden of Disease: An Introduction Kirk R. Smith Professor of Global Environmental Health
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Transcript of Global Burden of Disease: An Introduction Kirk R. Smith Professor of Global Environmental Health
Global Burden of Disease: An Introduction
Kirk R. SmithProfessor of Global Environmental Health
Designing Strategies for Neglected Disease Research Jan 20, 2009
Law 284.26, Public Policy 290, 190
What is health?• “Health is a state of complete physical,
mental and social well-being and not merely the absence of disease or infirmity.”– First of nine principles on first page of World
Health Organization Constitution adopted in NYC in July 1946 by 61 nations
– “spiritual well-being” added in 1999 by World Health Assembly, which at that time had 191 member states
• http://www.ldb.org/iphw/whoconst.htm
How would this be operationalized for the following common queries?
• What is the total impact of disease and injury in the population? -- the overall target for public health interventions?– Which diseases are most important for which groups?– Are things getting better or worse?
• How do we compare the impacts of different risk factors and potential interventions that affect different populations? – For example, what is the burden of disease from environmental
factors?– How does the impact of tobacco smoking compare to that from
air pollution?
Environmental Health Effects• Example of results from outdoor air pollution studies
– Asthma attacks– Missing workdays– Missing school days– Days with cough– Emergency room visits– Hospital admissions– Physician visits– Medication use– Daily death rate– Lung function– Self-reported health status– Etc.
• How can these be compared across time, cities, countries, age groups, sectors (e.g., transport versus power plants), etc.?
• Let alone compared with the health impacts from completely different risk factors, such as water pollution, lead exposure, high cholesterol, unsafe sex, etc.?
Ultimate Measure of Ill-health?
• Death is most common– Easy to determine– Commonly tabulated
• Severe problems as a measure– Everyone dies– Health never achieved– Age is clearly important
• Deaths + Illness = ?
Combined Measure• What else to use?
– Money? Are you kidding?– Is used in legal and other realms, but not
appropriate for public health• Most fundamental deprivation is loss of time:
– Same potential life length shared by all humans – The degree to which a person does not achieve this life
length is a measure of ill-health– Can be used for disabilities, as well, but need to weight
relative severity of disabilities as well as tabulate their duration
Health Adjusted Life YearsHALY
• Basically the number of fully healthy life years lost to a particular disease or risk factor.
• Considers the age at which the disease or death occurs and the duration and severity of any disability created.
Global Burden of Disease Database
• Developed at Harvard University originally for the World Bank
• Extended greatly in the mid-1990s and now adopted by the World Health Organization– Updated database published on web each year and
summarized in World Health Report• Dozens of countries now have NBDs• Even states (provinces) and cities have them,
including SF and LA
Need for a C4 Database in Health(Which we have had in many other fields for long periods)
• Combined mortality and morbidity• Complete
– Much of the world unrepresented in past databases– Many important disabilities unaccounted
• Consistent definitions of disease states• Coherent
– Deaths by disease need to add to total• By age and sex• Match with demographic stats
– No natural discipline, i.e. no import stats from the afterlife tabulating how many died of what
Just having coherence in mortality is valuableGlobal Deaths in 2002
0
5
10
15
20
25
0-4 5-14 15-29 30-44 45-59 60-69 70+
Age Groups
MillionDeaths
LDCs
MDCs
Total PopulationLDCs – 4.78 billionMDCs – 1.45 billion
Total Global Deaths in 2002: 57 million
Disability Adjusted Life YearThe DALY, a kind of HALY
• Principle #1: The only differences in the rating of a death or disability should be due to age and sex, not to income, culture, location, social class.
• Principle #2: Everyone in the world has right to best life expectancy in world
• DALY = YLL + YLD– Years of Lost Life (due to mortality)
– Years Lost to Disability (due to injury & illness)
Years of Lost Life: ExamplesAge at Death Female Male0 82.5 80.01 81.8 79.55 78.0 75.415 68.0 65.425 58.2 55.535 48.4 45.650 34.0 31.080 8.9 7.5100 2.0 1.5
100
What is Meant by “Disability?”• Impairment: Symptoms at organ level, e.g.,
broken leg• Disability: Objective alteration of behavior or
performance at the individual level, e.g., cannot walk
• “Handicap”: Changed interaction with others at the social/environmental level, e.g., cannot work
• http://www.disabilityhelper.com/Disability-Impairment-Handicap.htm
Schema for Assessing Non-fatalHealth Outcomes
Disease Impairment
Polio Paralyzed legs
Brain Mild mentalinjury retardation
Disability “Handicap”
Inability Unemployedto walk
Difficulty Sociallearning isolation
Whom do you ask to determine disability weights?
• Patient• Family• Caregiver• Health professional• Public health experts• Public at large• Insurance companies and lawyers (court cases)
Used in GBD
Time
Accident
ReportedDisabilityWeight
1.0
When do you ask?
Classes of Disability Weights, with examples
1: 0-0.02 Vitiligo on face2: 0.02-0.12 Diarrhea, sore throat3: 0.12-0.24 Radius fracture in stiff cast4: 0.24-0.36 Below the knee amputation5: 0.36-0.5 Down syndrome, COPD6: 0.5-0.7 Unipolar depression, tetanus7: 0.7-1.00 Psychosis, quadriplegia
Top Ten Causes of Disability in 15-44 year olds (2000)
Male FemaleUnipolar depression 13.9 18.6Alcohol disorders 10.1Schizophrenia 5 4.8Bipolar depression 5 4.4Fe-Deficiency anaemia 4.2 5.4Hearing loss 4.1 3.6Road traffic 3.8HIV/AIDS 3.2 2.5Drug use 3COPD 2.6Obstructed labor 4Chlamydia 3.3Abortion 3.1Panic disorder 2.8
Percent of Total YLDs
Sample DALY CalculationsDiseases A and B
• A. 100,000 children are stricken for 1 week with a disability weighting of 0.3; 2% die at 1 year old.
• B. 100,000 adults are stricken for 2 years with a disability weighting of 0.6; 20% die at 80 years old.
• A: YLL (= 2000 x 80) + YLD (=100k x (7/365) x 0.3) = 160,000 + 575 = 160,600
• B: YLL (= 20,000 x 8) + YLD (=100k x 2 x 0.6) = 160,000 + 120,000 = 280,000
Global Burden of Disease DatabaseWorld Health Organization
Being completely updated2007-2009
Occam's Razor• “One should not increase, beyond what is necessary,
the number of entities required to explain anything”
• Occam's razor is a logical principle attributed to the 14th Century philosopher William of Occam (or Ockham). The principle states that one should not make more assumptions than the minimum needed. This principle is often called the
Principle of Parsimony
The DALY Passes Occam’s razor criterion, because it reveals something different from deaths
Deaths DALYs 1 – Cancer 12.4% 5.3% (4) 2 - Heart 12.3% 3.8% (7) 3 - Stroke 9.2% 3.1% (9) 4 - ARI 7.1% 6.6% (1) 5 - HIV 5.3% 6.1% (3) 7 – Perinatal 8 - Diarrhea ? - Depression
4.4% 3.8% 0.03%
6.2% (2) 4.2% (6) 5.3 % (5)
Examples of Using a C4 database:World DALYS Lost (2000)
Pop million
Deaths million
Deaths per 1000
DALYs million
DALYs Per Death
LDCs 4693 43.3 9.2 1256 29.0
MDCs 1352 12.4 9.2 216 17.4
World 6045 55.7 9.2 1472 26.4
Impact of Development on Women and Children
W & C share of Pop
W & C share of DALYs
South Asia 66% 71%
Western Europe 60% 49%
World 65% 67%
Children under 15 years in 2000
2000
World - Deaths
0 5 10 15
Road Traff ic
Child Cluster
TB
Diarrhea
Perinatal
COPD
HIV
ARI
Stroke
Cancer
Heart (Ischaemic)
Percent of Total
World Deaths in 2000
Child Cluster Diseases: the World’s Largest Scandal
• 1.4 million children• Rates in LDCs are
thousands of times those in MDCs (Africa = 4700x that of W. Europe)
• Vaccine coverage in Africa went from 60% in 1990 to 46% in 1999
• Has stayed at 70% in South Asia for many years
Measles 777000Tetanus 309000Pertussis 296000Diphtheria 3400Poliomyelitis 675
Total Global Deaths in <5y
Relative Risks between Poor Africa and USA
• Chance of woman dying in childbirth: 400 times greater
• Child dying of diarrhea: 400 times• Of pneumonia: 500 times• Of measles: 4000 times
• Similar in South Asia (India, Bangladesh, etc)
2000
World - DALYs
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
Congenital
COPD
Maternal
TB
Malaria
Road Traffic
Stroke
Malnutrition
Child Cluster
Heart (Ischaemic)
Diarrhea
Cancer
Depression
HIV
Perinatal
ARI
Percent of Total
World DALYs in 2000
The major disease targets for publichealth interventions in the worldtoday
Almost allWomen &Children
2000
North America - Deaths
0.0 5.0 10.0 15.0 20.0 25.0
Dementia
Diabetes
ARI
COPD
Stroke
Heart (Ischaemic)
Cancer
Percent of Total
20002000
North America - Deaths
2000 North America - DALYs
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Osteoarthritis
Hearing loss
COPD
Diabetes
Dementia
Road Traffic
Stroke
Alcohol
Heart (Ischaemic)
Depression
Cancer
Percent of Total
20002000
The major disease targets for public health interventionsin the USA
222
178
118
107
92
90
86
86
75
67
67
59
59
52
47
39
0 50 100 150 200 250
Very poor Africa
Poor Africa
Poor Eastern Med
Poor South Asia
All Men
Former USSR
Poor Latin America
All Women
Middle income South Asia
Middle income Latin America
Eastern Europe
China +
Middle income Eastern Med
North America
Western Europe
Japan, Australia +
DALD/capita
Disability AdjustedLost Days = DALY x 365
2000
Global
0
100
200
300
400
500
600
Very poor Africa 548 57 174 264 191 193 218 212
Poor South Asia 307 44 75 80 114 157 169 159
Poor Latin America 198 34 74 75 93 120 140 160
Middle Income East Asia 146 24 44 43 67 107 139 158
North America 35 14 51 43 58 87 110 111
Western Europe 29 11 39 33 48 79 98 110
Japan/Australia 32 13 31 27 41 59 75 91
0-4 5-14 15-29 30-44 45-59 60-69 70-79 80+
DALDsPer Capitaby AgeGroup
SelectedWorld Regions
2000
Annual loss per person
Time
The Classic Epidemiological Transition
Non-CommunicableDiseases
Infectious Diseases
Cancer
CVD
Disease Categories• I - Traditional, Communicable
– Infectious, maternal, perinatal, nutritional• II - Modern, Non-communicable
– Cancer, heart, neuro-psychiatric, chronic lung, diabetes, congenital
• III - Injuries, Non-Transitional– Unintentional
• Motor vehicle, poisoning, falls, fire, drowning
– Intentional• Suicide, violence, war
Classic Epi Transition
• I. Infectious diseases decline during development
• II. Chronic disease rise during development• III. Injuries show no pattern during
development and are thus “non-transitional”
Empirical Test of the Epi Tranistion
• Does it hold up to examination using the first C4 database?
• Classic epidemiologic transition only deals with mortality, thus here termed the “Mortality Transition”
• “Epidemiologic Transition” here applied to same evaluation using DALYs
Epidemiological Transition - Age Adjusted
98
9
32
46
168
112
87
120
111
129
29
12
25
28
37
0 50 100 150 200 250 300 350 400
World
High
Upper Middle
Lower Middle
Low
Inco
me
Gro
up
DALYs per thousand
I - "Infectious" II - "Chronic" III - Injuries
Epi Transition: Updated• In terms of actual age-adjusted impact on
populations, all classes of disease decline during development– I. Declines dramatically at every level– II. Declines slowly, but with little decline seen across
middle income regions– III. Declines in a similar way to II and thus is not “non-
transitional”• Better to be rich for all major types of ill-health,
although there are exceptions for individual diseases
Comparison of GBD Estimates for 2005 with GBD for 1990
• Population: 5.3/6.4 billion (+21%)• Deaths: 50/64 million (+28%) • DALYs: +7%• DALYS/capita: -11%• I = 44/38.5%; • II = 41/48.9%; • III = 15/12.5%
WHO Databases
Changes in Important Diseases: 1990-2005What is happening with each?
• Diarrhea: 7.3/3.9% (-42% in absolute terms)• ARI: 8.5/5.9% (-25%)• Malaria: 2.3/2.3% (-6%)• Lung Cancer: 0.65/0.8% (+32%)• TB: 2.8/2.1% (-18%)• HIV: 0.8/5.6% (7.4 times as much)• Depression: 4.7/5.8 (+29%)
WHO Databases
Can we reach public health?
• Is there a absolute value of health (lost DALYs) beyond which society does not have an obligation to exceed?
• Is there a cost per unit improvement in health ($ per DALY) above which society does not benefit from further expenditure?
World Health Reports – 2002, 2001
4.9 million deaths/y
Global Burden of Disease from Top 10 Risk Factorsplus selected other risk factors
0% 2% 4% 6% 8% 10%
Climate change
Urban outdoor air pollution
Lead (Pb) pollution
Physical inactivity
Road traffic accidents*
Occupational hazarads (5 kinds)
Overweight
Indoor smoke from solid fuels
Lack of Malaria control*
Cholesterol
Child cluster vaccination*
Unsafe water/sanitation
Alcohol
Tobacco
Blood pressure
Unsafe sex
Underweight
Percent of All DALYs in 2000
Environmental Risk Factors
Entry into GBD databases• Best single modern book covering the GBD and CRA ideas, methods,
and results, but without full detail and sophistication/complexity: Global Burden of Disease and Risk Factors, (Lopez, Mathers, Ezzati, Jamison, Murray) Oxford University and World Bank Presses, 2006. 475 pp. Fully downloadable at http://www.dcp2.org/pubs/GBD which also has links to data used in the book.
• Best single page to find GBD data divided by world regions defined in several ways (WHO regions, World Bank regions, income groups etc.) for 2004. http://www.who.int/healthinfo/global_burden_disease/2004_report_update/en/index.html
• For projections to 2030 and links to dozens of other publications, see http://www.who.int/healthinfo/global_burden_disease/en/index.html
• The full set of background materials and pubs of the previous (2004) Comparative Risk Assessment (CRA) covering 26 major risk factors, environmental and other: http://www.who.int/healthinfo/global_burden_disease/cra/en/index.html
• Full databases for the previous CRA study: http://www.who.int/healthinfo/global_burden_disease/risk_factors/en/index.html
• Description of the GBD/CRA 2005 Revisions now underway: http://www.who.int/healthinfo/global_burden_disease/GBD_2005_study/en/index.html
Thank you.
Kirk R. [email protected]://ehs.sph.berkeley.edu/krsmith/