Introduction to DALY and burden of disease

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

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Introduction to DALY and burden of disease

  1. 1. Burden of Disease: Introduction Arindam Basu School of Health Sciences, University of Canterbury, arindam.basu@canterbury.ac.nz February 24, 2014
  2. 2. Part I: DALY AS A SINGLE GAP BASED MEASURE OF POPULATION HEALTH
  3. 3. Health STATE of WELL-BEING BIRTH DEATH
  4. 4. Health Physical, Mental, Social WELL-BEING BIRTH DEATH
  5. 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. 6. Health Complete Physical, Mental, Social WELL-BEING BIRTH DEATH
  7. 7. Health As a “STATE” WATER AS A METAPHOR OF HEALTH and CHANGE of STATE Image source: Wikimedia commons
  8. 8. Health State of Complete Physical, Mental, Social WELL-BEING BIRTH DEATH
  9. 9. What Is Absence of Health? Disease? Infirmity? What is Absence of Disease? Health?
  10. 10. 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)
  11. 11. “Health is Wealth” (Ancient Saying)
  12. 12. Provocation: “Is Health Resource? Or is Health Merely a “State of Existence”? Or Both? How do we reconcile?
  13. 13. Context of Measuring Health PATIENTS PAYERS PROVIDERS MANAGERS
  14. 14. 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)”
  15. 15. Constraints and Limitations of a Summary Measure of Health The Measure Must Be Consistent The Measure Must Be Comparable and Make Sense
  16. 16. “ONE MEASURE TO RULE THEM ALL”
  17. 17. The Principle “May You Live a Long Life in Good Health”!
  18. 18. Health Gap The Ideal: Individuals Live Standard Life Expectancy At Full Length Health Gap: State of Population Health Compared to a Normative Goal
  19. 19. 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
  20. 20. 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)
  21. 21. 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
  22. 22. YLD for Populations Age-Specific Prevalence of the Disease or Sequela Multiplied By Age-Specific Disability Weight
  23. 23. … AND ONE FORMULA To RULE THEM ALL … DALY = YLL + YLD
  24. 24. PART II: ESTIMATE GLOBAL BURDEN OF DISEASE USING DALY
  25. 25. 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
  26. 26. World • Data from – 187 Countries – 21 Regions • Basis: – Geographical Contiguity – Epidemiological Homogeneity
  27. 27. 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
  28. 28. 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
  29. 29. 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
  30. 30. Estimation of YLD • Prevalence of Sequela * Disability Weight
  31. 31. 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
  32. 32. DALYs For Males, GBD 2010
  33. 33. AGE-WISE DISTRIBUTION of DALYs, Women, GBD 2010
  34. 34. Change in the DALYs Between 1990 - 2010
  35. 35. Let’s Start Playing with the Data: http://www.healthmetricsandevaluation.org/gbd/visualizations/g bd-insight

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