1. Anuj Mundra Moderator – Dr. Abhishek Raut

2.  What is “burden of disease”  Need for measuring burden of disease?  Measures of population health  Life expectancy  Healthy life expectancy  Disability adjusted and disability free life expectancy  Quality Adjusted Life years  Incidence, prevalence, mortality  DALY  Global Burden of Disease study

3. The burden of disease is the impact of disease in a population. It is an approach to the analysis of health problems, including loss of healthy years of life. An important concept for public health and for other professions interested in the societal impact of ill-health, including injuries and disabilities.

4.  For public health interventions to be effective and appropriate for improving population health, understanding of the key challenges and their dynamics is necessary both regionally as well as globally.  The global health landscape is undergoing rapid transformation and the trends differ globally.  Recently the role of disability in estimating disease burden & health status is increasingly being projected than mortality only.

5.  Commercial and professional interests often lead to implausible claims of the number of deaths or cases due to a particular disease.  To respond to these challenges, high-quality comparable and combined data on the size and trends in mortality and morbidity are essential.  For this we need to make a comprehensive assessment of the health of each population by ensuring that all deaths by cause add up to the total number of deaths and similar criteria be applied to classifying cases of disease &/or the morbidity due to it.

6. Health expectancies Measures the years of life gained or improved quality of life Disability Free Life Expectancy (DFLE) Disability Adjusted Life Expectancy (DALE) Health Adjusted Life Expectancy (HALE) Quality Adjusted Life Expectancy (QALY) Health Gap measures lost years of full health in comparison with an ‘Ideal’ or a standard state or a goal. Potential Years of Life Lost (PYLL) Quality Adjusted Life Years (QALY) Disability Adjusted Life Years (DALY)

7. Mortality Data (Age specific death rates) Morbidity Data (morbidity, disability, health related quality of life) Life table technique Summary measure of population health (Healthy life expectancy or healthy life years)

8.  Indicates the number of years a person would live if prevailing patterns of mortality at that age were to stay the same throughout its life.  Composite measure of age specific mortality rates.  Indicates overall health status & mortality patterns across age groups in a region.  Mortality rates change with time and hence life expectancy with age (mostly higher than estimated figures due to falling death rates).  Does not give an estimate of impact of a particular disease.

9.  Globally – 71 yrs  Low income countries -62 yrs  High income countries – 79yrs  Lowest: Sierra-Leone (46 yrs)  Highest: Iceland & Japan–83yrs  India – 67.3 yrs (M), 69.6 yrs (F)

10.  HALE= life expectancy – periods of less than a full healthy life (healthy life years)  The number of years that a person at a given age can expect to live in good health if current rates of mortality and disability would remain constant (using the health utility index).  Also called as healthy life expectancy  Grades the severity of disease/disability across full spectrum and adjusts time lived at each age in a life table by severity weighed prevalence.

11. Data Source Data Healthy life expectancy Life table technique Mortality data Mid year population estimates Health data Age specific death rates Self assessed health

14. It integrates the data on Mortality Long-term institutionalization Activity limitations Measures both quality and quantity of life Severity weighing done across four states of health No activity limitation Activity limitation in leisure activities or transportation Activity limitation at work, home &/or school Institutionalization in a health care facility.

15.  Classifies disability in a dichotomous way: those above threshold contribute no time whereas those below threshold contribute a full year to a healthy (disability free) life.  DFLE is the coarsest measure of health expectancy.  Does not give weightage to the severity of disability once it has crossed the threshold.

17. Advantages of health expectancy measures Health expectancies are an adaptation of life expectancy taking into account that not all years of remaining life expectancy are lived in good health. They capture the health status of a population in a single number which provides an easy and intuitive way to interpret the results. Limitations of health expectancy measures Not easy to attribute a populations health status (both good or bad) to any particular disease, injury, risks or other conditions

18.  A composite measure of gain in life expectancy and health related quality of life.  Combines length of life and quality of life.  It is quality adjustment to years of life gained or length of time for which the quality of life improved or both due to an intervention.  Quality of life is calculated by obtaining a measure of health state of patients using a generic measure like EQ-5D and comparing with a standard population

19.  Advantages of QALY Can be applied to any intervention whether it increases life expectancy without improving quality of life or vice versa, improves both or improves one at the cost of other. Useful for cost-effective analysis.  Disadvantage- It is argued that longevity and quality should not be compared in the same metric.

20. Incidence Prevalence Mortality rates- Age-specific mortality rates Cause specific mortality rates Case fatality rates Disability Adjusted Life Years (DALY)

21. Incidence – no. of new cases of a disease. Incidence rates – no of new cases of a disease per year Prevalence – proportion of people in a population living with a disease (new + old) at any given point of time or over a period of time.

22. No of deaths per year due to a disease or a health condition. Can be calculated for different age/age groups (thus indicates the burden of any disease at different stages of life). Case fatality rates indicate about the severity of the disease. Incidence, prevalence and mortality do not give a complete picture regarding the impact/burden of a disease particularly about quality of life. May be difficult to compare across regions due to lack of uniformity and consistency in data.

23.  An absolute health gap/health loss measure.  Measures population health comprehensively with the ability to express the contribution of diseases, injuries, & risks as a proportion of total burden of disease.  Quantifies loss of health from mortality and morbidity against an ideal state of life free of disease.

24. Ranges from 0 (no disability) to 1 (death). 1DALY = 1 year of healthy life lost Converse of the QALY (quality adjusted life year) Uses life table to compare with maximum life expectancy (i.e.lowest age specific mortality)

25. Years of life lost due to premature death from a disease or risk factor. YLL = N * LN= no of deaths L= standard life expectancy at age of death

26. Years of life lived with any short-term or long-term health loss. YLD = I * L * Disability Weight I= no. of Incident casesL= duration until remission or death Prevalence YLD YLD = P * Disability Weight P= no. of prevalent cases (Used in GBD study 2010)

27. A disability weight is a weight/severity factor that reflects the severity of the disease on a scale from 0 (equivalent to perfect health) to 1 (equivalent to death). Translates morbidity into healthy life years lost, thus enabling comparison of morbidity and mortality. Years Lost due to Disability (YLD) are calculated by multiplying the incident cases by duration and disability weight for the condition.

28. Disability classSeverity weightsConditions 10.00 – 0.02Vitiligo on face, malnutrition 20.02 – 0.12Watery diarrhoea, sore throat, anemia 30.12 – 0.24 Radius # in cast, infertility, erectile dysfunction, RA, Angina 40.24 – 0.36Below knee amputation, deafness 50.36 – 0.50 Rectovaginal fistula, Mild mental retardation, Down syndrome 60.50 – 0.70Unipolar major depression, blindness, paraplegia 70.70 – 1.00Active psychosis, dementia, Quadriplegia Source: The Global Burden of Disease report summary 1990

29. These are the social value weights applied in the calculation of DALY. Uses the principle that not all life years that are lost have equal value. 2 types of weighting: Age weighting, and Time discounting Leads to a difference in the values of Incidence and prevalence YLDs which is otherwise approximately same. Lack of consensus for universal use and hence not used in the GBD 2010. Some authors suggest to calculate DALY with & without social weighting for comparability with various scenarios.

30. A higher weight is given to the healthy life years lived in the so assumed socially more important age group. Age weighting formula is given by - Cxe - β x C- constant (0.1658), β - constant (0.04),x- concerned age

31. Time discounting discounts years of healthy life lived in the future to prevent giving excessive weight to deaths at a younger age. Usually the discount rate is taken as 3%. It is a more common practice in economic assessments and motivates policy makers to invest in currently available intervention measures, though they may be less effective than from saving resources for future programs. It can be calculated by the following formula - e -r(x-a) r- discount rate,x- concerned age, a- age to which burden will be assigned

32. Combining both age weighting and discounting gives us the following formula for YLL and YLD A+L YLD = N * DW * ʃ {KCxe - β x e -r(x-a) + (1-K) e -r(x-a) }dx A A+L YLL = M * ʃ {KCxe - β x e -r(x-a) + (1-K) e -r(x-a) }dx A N=no of cases,M=no of deaths, K=modulating factor (1 if age weighting is applied else 0) A & L= age at onset and duration (YLD), and age at death and life expectancy at age of death (YLL)

33. Scenario (K,r)Age weightingDiscounting rate(%)YLDYLLDALY DALY [0,0]No011.025.036.0 DALY [1,0]Yes012.316.729.1 DALY [0,0.03]No38.39.718.0 DALY [1,0.03]Yes39.56.716.2

35. Doesn’t help determine the right interventions. The true “burden” of disease will depend on the economic, family and social circumstances. Does not assess qualitative difference in outcomes Discriminates against young and the old

36. A- Global B-High Income Countries C- low Income Countries

42. Ranking of causesYLD 2013YLL 2013 1Major Depressive disorderIHD 2Back PainLRI 3Iron DeficiencyTB 4MigraineNeonatal encephalitis 5COPDPreterm birth Complications 6Hearing disorderDiarrhoea 7Neck painStroke 8DiabetesCOPD 9AnxietySelf Harm 10Refraction errorRoad Injuries

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