Global Burden of Disease and the Role of Environmental Risk Factors Kirk R. Smith

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Global Burden of Disease and the Role of
Environmental Risk FactorsKirk R. Smith

• October 30, 2002

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Two public health questions

• What is the total impact of disease and injury in
  the population? -- the overall target for public
  health interventions?
• How do we compare the impacts of different
  diseases, risk factors, and interventions that
  affect different populations? For example, what
  is the burden of disease from environmental
  factors in populations at different levels of
  development?

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Ultimate Measure of Ill-health?

• Death is most common
• Easy to determine
• Commonly tabulated
• Severe problems
• Everyone dies
• Health never achieved
• Age is clearly important
• Deaths Illness ?

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Need for a C4 Database

• Combined mortality and morbidity
• Complete
• Much of the world unrepresented
• Many important disabilities unaccounted
• Consistent definitions of disease states
• Coherent
• Deaths by disease add to total
• Statistics match by age and sex

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Combined Measure

• What else to use?
• Money? Are you kidding?
• Most fundamental deprivation is loss of time
  life length shared by all humans
• Can be used for disabilities, but need to weight
  relative severity of disabilities

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Quality Adjusted Life YearsQALY

• 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.

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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
• Dozens of countries now have NBDs
• Even states (provinces) and cities have them,
  including SF and LA

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Distribution of Global Deaths
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Disability Adjusted Life YearThe DALY, a kind of
QALY

• 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.
• 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)

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Years of Lost Life Examples
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Examples of Disability Weights

• 1 0-0.02 Vitiligo on face
• 2 0.02-0.12 Diarrhea, sore throat
• 3 0.12-0.24 Radius fracture in stiff cast
• 4 0.24-0.36 Below the knee amputation
• 5 0.36-0.5 Down syndrome, COPD
• 6 0.5-0.7 Unipolar depression, tetanus
• 7 0.7-1.00 Psychosis, quadriplegia

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Schema for Assessing Non-fatalHealth Outcomes

• Disease Impairment
• Polio Paralyzed legs
• Brain Mild mental
• injury retardation

• Disability Handicap
• Inability Unemployed
• to walk
• Difficulty Social
• learning isolation

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Definitions

• Impairment loss or abnormality of psychological,
  physiological, or anatomical structure or
  function
• Disability any restriction or lack of ability to
  perform an activity in the manner or within the
  range considered normal.
• Handicap disadvantage resulting from impairment
  or disability that limits or prevents the
  fulfillment of a role that is normal (depending
  on age, sex, social, and cultural factors).

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Sequence (can be bidirectional)

• Exteriorization of symptoms at organ level
• Objective alteration of behavior or performance
  at the individual level
• Changed interaction with others at the
  social/environmental level

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Neuropsychiatric Conditions

• Unipolar depressive disorders
• Bipolar disorder
• Schizophrenia
• Epilepsy
• Alcohol use disorders
• Alzheimer and other dementias
• Parkinson disease
• Multiple sclerosis
• Drug use disorders
• Post-traumatic stress disorder
• Obsessive-compulsive disorder
• Panic disorder
• Insomnia (primary)
• Migraine
• Other neuropsychiatric disorders

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Whom do you ask?

• Patient
• Family
• Caregiver
• Health professional
• Public at large
• Insurance companies

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When do you ask?
1.0
Reported Health State Utility
Accident
Time
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Comparative Disability Weights

• Unipolar/bipolar depression 0.6
• Schizophrenia 0.6-0.7
• Terminal cancer 0.8
• Blindness 0.6
• Congestive heart failure 0.3
• Down syndrome 0.6
• Burns gt60 of body 0.3-0.5
• Symptomatic COPD 0.4

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The leading causes of years lived with
disability, worldwide, 1990
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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

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2000 Deaths vrs DALYs
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World DALYS Lost (1990)
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Impact on Women and Children
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2000
2000
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2000
2000
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2000
2000
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2000
2000
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Top Ten Diseases - 1990
Africa Sub Saharan Africa
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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

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Epidemiologic Transition
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Epidemiologic Transition-B
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Epidemiologic Transition-C
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Comparison of GBD Estimates for 2000 with GBD for
1990

• Population 5.3/6.0 billion (15)
• Deaths 50/56 million (10)
• DALYs 6.7
• DALYS/capita -7
• I 44/42
• II 41/46
• III 15/12

World Health Report, 2001
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Changes in Important Diseases 1990-2000

• HIV 0.8/6.1 (8.1x in absolute terms)
• TB 2.8/2.4 (0.93x)
• Malaria 2.3/2.7 (1.3x)
• ARI 8.5/6.6 (0.84x)
• Diarrhea 7.3/4.2 (0.62x)
• Lung Cancer 0.65/0.8 (1.3x)
• Depression 4.7/5.3 (1.21x)

World Health Report, 2001
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Overview 2002 SF YLLs (2000)
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1997 Los Angeles Burden of Disease
DALY Rank
Death Rank
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The leading causes of DALYs at ages 15-44 years
worldwide, 1990
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Ten leading causes of DALYs in developed regions,
1990
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Can we reach public health?
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Harvard Burden of Disease Unit http//www.hsph.ha
rvard.edu/organizations/bdu/ SF Burden of
Disease and Injury Study http//www.medepi.org/sfb
di/ World Health Report 2002 http//www.who.int
/whr/ WHO Comparative Risk Assessment
Methods http//www.ctru.auckland.ac.nz/CRA/
Thank you.