Global burden of disease (GBD) - How to measure disease ...pingpong.ki.se/public/pp/public_courses/course... · - How to measure disease burden and importance of risk factors [email protected]

Global burden of disease (GBD)

- How to measure disease burden

and importance of risk factors

[email protected]

10 September 2010 2

Measuring burden of disease

� What is burden of disease?

� Why measure burden of disease?

� How to measure burden of disease?

� The burden of disease in different countries

� The importance of risk factors to the burden of disease

10 September 2010 3

Diseases/diagnoses

� There are approx 137 different disease diagnoses

� Different interest groups emphasize different

diseases as “major public health problems”

� With limited resources within health care, how

and which diseases should be given priority?

10 September 2010 4

Global Burden of Disease (GBD)

WHO-project

� During the past decade, WHO and the World

bank have carried out a project with the aim to

develop one measure on the global burden of

disease

� This was the origin to the Global Burden of

Disease Project (GBD)

10 September 2010 5

What is burden burden of disease?

10 September 2010 6

A measurement of the gap between

the current health of the population

and an ideal situation

where everyone in the population

lives in old age in full health.

10 September 2010 7

Summary measures of population health

(SMPH)

Measures of population health

that combines information about both

mortality and disability

into a single number

10 September 2010 8

Global Burden of Disease (GBD)

WHO-project

� Several different methods and measures were

introduced to measure burden of disease in the

GBD-project

�HALE, QALY, etc

� The main measure that was used was DALY =

Disability Adjusted Life Years

10 September 2010 9

Why measure burden of disease?

10 September 2010 10

With a combined measure of

population health it is possible to:

� Compare health in a population over time or between different populations

� Identify and quantify inequalities

� Provide appropriate and balanced attention to non-fatal health outcomes

� Inform debates on priorities for health service delivery, planning, prevention etc.


Using DALY to measure burden of

disease


DALY

(Disability adjusted Life Years)

DALY is a combined measure on the

disease burden that describes ill health

in the population by combining

information about both

mortality and disability


DALY

� Most frequently used to measure burden of disease

� What specifically is measured is the time (years) with optimal health that is lost due to:

�Premature death

� Lost of function (disease)


The two basic components in DALY is thus:

� YLL (Years of Life Lost)

1 YLL = one year lost due to premature death

� YLD (Years of Lost due to Disability)

1 YLD = one year lost due to, disability


To define lost years..

� The highest observed life expectancy for any

nation was chosen i.e., Japan.

�With a life expectancy: 82.5 years for women

�With a life expectancy: 80 years for men


Which data are needed to

calculate DALY?

� Population: Age, sex, life expectancy

� Mortality, distributed by age and sex and cause of death

� Epidemiological data (incidence and duration) on non-

fatal disease, distributed by age and sex

� Valuation of disability


Valuation (weighting) of disability (DW)

Valuation of how difficult the loss of

function is presumed to be.



� One example is a scale, i.e.,

�Disability is graded on a scale 0-1,

� 0= No disability, complete health,

� 1=Complete disability, death



� One example is a scale, i.e.,

�Disability is graded on a scale 0-1,

� 0= No disability, complete health,

� 1=Complete disability, death


Complete health 0

Death 1

*Severe depression

*Cold

*Amputation of a leg

*Blindness

*Severe asthma

*Deafness

0.2

0.4

0.6

0.8

DISCUSSIONS

� Grade the different diseases on a scale between

1- and 0

� Think- you will have this condition during one day

(but you do not know for how long it will last).

� Loss of function ≠ handicap

Have in mind: loss of function

� The limitation a disease and injury bring to the

ability to function normal is

�The same for all people

� Loss of function ≠ handicap

�Ex. An amputated leg is valuated the same in DALY

irrespective of being a farmer in Indonesia or an office

worker in Sweden

Who should make these values?


� Whose values?

� Patients

� This usually changes over time, adopt to disease

� General population

� Difficult for people to value diseases that they are not very aware of

� Health workers

� Often think the situation is worse than the patients

� Families to patients

� Often think the situation is worse than the patients

� In GBD-study

� Both population and highly educated people

How is YLL calculated?

� YLL = Years of life lost due to premature death

� The calculation of YLL for a specific diagnose (distributed by age and sex),

is made by multiplying number of deaths with life expectancy at point

when death occur.

YLL = N * L

Where;

N = number of deaths

L= Life expectancy

How is YLD calculated?

YLD = Years of Lost due to Disability

� The calculation of YLD for a specific diagnose (distributed by age and sex)

is made by multiplying the incidence (I) with expected time to recovery

or death (L) with disability weight (0-1).

YLD = I * L * DW

Where;

I = Number of incident cases

L= Expected time to recovery or death

DW = Disability weight

How is DALY calculated?

YLL + YLD = DALY

How is DALY calculated?

YLL + YLD = DALY

Calculating DALY (example individual level)

Example 1: A man who is completely healthy and dies 80 years old. 0 YLL,

0 YLD 0 DALY

Death 1

Complete 0

health

80 years


Example 2: This man gets a knee injury at the age of 60 (before this he is completely healthy) and needs to amputate his leg. At the age of 80 he dies.

6 YLD, 0 YLL, 6 DALY

Death 1

Complete 0

health

80 years

*DW (amputation) = 0.3

*Healthy years lost= 20

YLD = 0.3 X 20 =6


Exempel 3: A man who is completely healthy and dies at the age of 75 years in coronary heart disease.

5 YLL, 0 YLD, 5 DALY

Death 1

Complete 0

health

80 years

*Years of life lost

due to premature

death= 5

YLL =5


Example 4: A man suffers from severe depression at the age of 20 years old. At the age of 30 he is cured. At the age of 50 he is involved in an accident and becomes blind on both eyes. At the age of 65 years he dies in a stroke.

21.2 YLD, 15 YLL, 36.2 DALY

Death 1

Complete 0

health

80 years

DW for;

*severe depression =0.83

*blindness = 0.43

Healthy years lost due to;

*severe depression = 10

*blindness = 30

*years of life lost due

To premature death = 15

YLD = 0.83 X 10 + 0.43 X 30=21.2

YLL = 15

DALY a population measure

� DALY is a population measure

� Enables to calculate the total sum of the

combined loss of all premature deaths and loss of

healthy life from disability from specific diseases

world wide

DALY a population measure

� DALY is a population measure

� Enables to calculate the total sum of the

combined loss of all premature deaths and loss of

healthy life from disability from specific diseases

world wide

Nr.

of

P

E

R

S

O

N

S

/1000

Years lost due to

premature death

Years lost due to

disability

Diagnose criteria's

YLL and YLD can be summarized for all disease

categories and subcategories in order to obtain

one DALY measure for; example neuro-

psychiatric conditions, coronary heart disease,

cancers etc.

Ex: Neuro-psychiatric diseaseMen DALY YLL YLD

Neuro-psychiatric disease 154569 33551 121018Unipolar depression 28926 155 28771Bipolar affective disease 6284 0 6284Schizophrenia 8142 101 8041Epilepsia 3916 2245 1670Alcohol addiction 28132 9017 19115Dementia 37255 9763 27492Parkinson 5527 1553 3974Multiple sclerosis 1847 864 1010Narcomania 6797 4756 2041Post traumatic stress syndrom 869 0 869Tvångssyndrom 1836 0 1836And a few more… … …. ….

What are the benefits with a summary

measure of population health that measure

both mortality and disability at the same

time?

How would you share the health-care

resources if you had the following

information?

Year of life lost due to premature death

(YLL) Sweden 2002, women

YLL women

0 20000 40000 60000 80000 100000 120000 140000 160000

Hjärtkärlsjukdomar

Maligna tumörer

Neuro-psykiatriska sjukdomar

Skador

Sjukdomar i luftvägarna

Mag-tarmsjukdomar

Luftvägsinfektioner

Diabetes

Medfödaa missbildningar

Infektioner

Sjukdomar i urin- och könsorgan

Muskuluskeletala sjukdomar

Övriga tumörer

Perinatala tillstånd

Endokrina sjukdomar

Näringsbrist

Hudsjukdomar

Graviditet och förlossning

Tandsjukdomar

Sjukdomar i ögon och öron

YLL

Years of Life lost due to disability (YLD)

Sweden 2002, women

YLD, women

0 20000 40000 60000 80000 100000 120000 140000 160000 180000 200000


Maligna tumörer


Skador


Mag-tarmsjukdomar


Diabetes


Infektioner



Övriga tumörer


Endokrina sjukdomar

Näringsbrist

Hudsjukdomar


Tandsjukdomar


YLD

Burden of disease (DALY)

Sweden 2002, women

DALY(0,0) Kvinnor

0 50000 100000 150000 200000 250000

Infektioner


Perinala tillstånd

Näringsbrist

Maligna tumörer

Övriga tumörer

Diabetes

Endokrina sjukdomar

Neuro- Psyk.

Ögon och öron

Hjärt- kärl.

Luftvägar

Mag- tarm

Urin- och könsorgan

Hud

Muskoloskeletala

Medfödda missbildningar

Tandsjukdomar

Skador


YLL(0,0)

YLD(0,0)

Year of life lost due to premature death

(YLL) Sweden 2002, men

YLL

0 20000 40000 60000 80000 100000 120000 140000 160000 180000 200000


Maligna tumörer

Skador


Mag-tarmsjukdomar



Diabetes


Infektioner



Endokrina sjukdomar

Övriga tumörer


Näringsbrist

Hudsjukdomar


Tandsjukdomar

YLL

Years of Life lost due to disability (YLD)

Sweden 2002, men

YLD

0 20000 40000 60000 80000 100000 120000 140000


Maligna tumörer

Skador


Mag-tarmsjukdomar



Diabetes


Infektioner



Endokrina sjukdomar

Övriga tumörer


Näringsbrist

Hudsjukdomar


Tandsjukdomar

YLD

Burden of disease (DALY)

Sweden 2002, men

DALY(0,0) Män

0 50000 100000 150000 200000 250000

InfektionerLuftvägsinfektioner


Näringsbrist

Maligna tumörer

Övriga tumörer

Diabetes

Endokrina sjukdomar

Neuro- psyk.

Ögon och öron

Hjärt- kärl.

Luftvägar

Mag- tarm

Urin- och könsorgan

Hud

Muskoloskeletala

Medfödda missbildningar

Tandsjukdomar

Skador


YLL(0,0)

YLD(0,0)

Which risk factors contributes to the

burden of disease?

Comparative Risk Assessment

(WHO-project)

� Continuation of the GBD-project

� The challenge: To compare a number of risk

factors and estimate the importance of their

influence on the disease burden.

Why include risk factors?

� Disease data is focused on curative needs

� Risk factors are possible to prevent

� Important for preventive measures

�Basis for prioritization and planning of health political

measures

Selected risk factors

� In total 26, mainly medically defined risk factors

�Probability of being among the leading causes to the

disease burden

�High probability for causality

�Possible to modify

�Access to reasonable complete data

Groups of risk factors

� Childhood and maternal malnutrition

� Diet and physical activity

� Sexual and reproductive health risks

� Addictive substances

� Environmental risks

� Occupational risks

� Other selected risk factors

Risk factors, examples

� Childhood and maternal malnutrition

� Underweight

� Iron deficiency

� Diet and physical activity

� Overweight

� High cholesterol

� Addictive substances

� Tobacco

� Alcohol

Results, low-income countries - high

mortality (WHO 2002)

Men (%DALY)

Underweight 14,9

Unsafe sex 9,4

Unsafe water/san 5,5

Indoor smoke 3,7

Zinc deficiency 3,2

Tobacco 3,4

Alcohol 2,6

Women (%DALY)

Underweight 15,0

Unsafe sex 11,0

Unsafe water/san 5,6

Indoor smoke 3,7

Iron deficiency 3,5

Vit A deficiency 3,5

Zinc deficiency 3,2

Results, high-income countries

(WHO 2002)

Men (%DALY)

Tobacco 17,1

Alcohol 14,0

Blood pressure 11,2

Cholesterol 8,0

Overweight 6,9

Fruit and veg.bles 4,3

Physical activity 3,3

Women (%DALY)

Blood pressure 10,6

Overweight 8,1

Cholesterol 7,0

Tobacco 6,2

Fruit and veg.bles 3,4

Alcohol 3,3

Physical activity 3,2

Attributable fraction

� How much of the disease burden can be avoided

if you take away a certain risk factor

�Need information about the Relative Risk

� This is the same between countries

�Prevalence of exposure

� Differ between countries

Exemple: High BMI in Sweden

� High BMI causes in total:

� 67 257 DALYs for men and

�61 453 DALYs for women

�Corresponding to 7.6% of the total disease burden in

Sweden

� This means that: 7.6% of the total burden of

disease can be avoided if obese persons

decrease their BMI

In the CRA-project, socio-economic factors

are not measured

� The risk factors are mainly medical defined

� We are now working on a project to include

socio-economic risk factors to investigate how

this may influence the burden of disease.

So is DALY a perfect measure?

Critics against DALY

� DALY is an important contributor in discussions

about priorities in public health questions. However:

� The measurement is difficult to understand immediately (not like for

example mortality, prevalence of disease etc).

� It is controversial to value diseases (DW)

� There is a risk that DALY gives a seeming objectivity.

� The measures are based on data assumed to be reliable (but this varies a lot

between countries).

� It is not always easy to find reliable data

Can you answer to the following questions?

� What is burden of disease?

� Why measure burden of disease?

� How is burden of disease measured?

� Why is it important to include risk factors to the

burden of disease?

Documents

Global burden of disease (GBD) - How to measure disease ...pingpong.ki.se/public/pp/public_courses/course... · - How to measure disease burden and importance of risk factors [email protected]