global burden of disease and health policy

GLOBAL BURDEN OF DISEASE - GBDFARHAD ZARGARI, MD, PHD – [email protected]

INTRODUCTION

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HEALTH CARE

نبی مکرم اسالم )ص(: العلم علمان، علم االدیان و علم االبدان

The holy Prophet of Islam, Mohammad bin Abdullah )PBUH(: The essential sciences are two, the science of religions, and the science of bodies.

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HEALTH CARE

Of all the objects in the world, the human body has a peculiar status, it is not only possessed by the person who has it, it also possesses and constitutes him. We can lose money, books and even houses and still remain recognizably ourselves, but it is hard to give any intelligible sense to the idea of a disembodied person.

Jonathan Miller

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– Dr. A.D. Lopez

Understanding the Burden of Disease. The Pfizer Journal. 2000

DEVELOPMENT OF HEALTHCARE POLICY

“Development of healthcare policy is not about predications or wish lists for the future, but rather it is a process that aims to challenge assumptions and encourage fresh thinking to better understand the future.”

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HOW MUCH COST FOR HEALTH IS RATIONAL?

If a car worth $10,000 would cost $15,000 to repair after an accident, an insurer would only pay $10,000. The impossibility of replacing the body, and the consequent absence of a market value for it, precluded any such ceiling on health costs.

GLOBAL BURDEN OF DISEASE - GBD

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GLOBAL BURDEN OF DISEASE

There are some 7 billion people in the world and hundreds of millions experience disease or injury each year. Taken as a whole, the combined pain, suffering, loss of productivity and unrealized hopes and dreams are our world’s burden of disease.

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The burden of disease approach is a systematic, scientific effort to quantify the comparative magnitude of health loss due to diseases, injuries, and risk factors by age, sex, and geography for specific points in time.

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The burden of disease can be thought of as a measurement of the gap between current health status and an ideal situation where everyone lives into old age, free of disease and disability.

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“Men do not think they know a thing until they have grasped the why of it.”

– Aristotle

“The purpose of the research into the global burden of disease was not only to measure and describe the health of the world but also, and more important in many ways, to explain why these events and phenomena have occurred.”

– Dr. A.D. Lopez

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The Global Burden of Disease study, begun in 1992, involved 100 collaborators in more than 20 countries. It attempted to quantify disease and injury burden of over 100 conditions and make projections out 30 years for 500 consequences or results of these conditions.

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The Global Burden of Disease study, published in Science in 1996, looked at the effect of disease not only on "lifespan" but also on "health span" for the first time. They did so by moving beyond mortality rates and creating a new measure called DALY. DALY stands for disability adjusted life year and is a measure that expresses one year of life lost to premature death and years lived with a disability of specified severity and duration; one year of life lost to poor health.

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The Global Burden of Disease Study 2010 )GBD 2010( has three related but distinct uses: to provide a coherent picture of which diseases, injuries, and risk

factors contribute the most to health loss in a given population;

to compare population health across communities and over time;

and to help guide an assessment of where health information systems are strong or weak by identifying which data sources are missing, are of low quality, or are highly uncertain

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GLOBAL BURDEN OF DISEASE SURPRISES-2020

1. Rapid rise of chronic disease 73% of GBD by 2020

2. High level mental illness 3.7% of GBD – depression

3. Violence, war, injuries 12% deaths worldwide

41% deaths < 20 years, USA

4. Alcohol and Tobacco Tobacco #1 instigator

Fastest gain, underdeveloped nations

5. Significant increase in cancer Number 1 killer in many

countries

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REASONS TO MEASURE BURDEN OF DISEASE

Assign priorities between different public health problems.

Compare strategies on a single public health problem in terms of impact.

Choose health interventions that target different health problems with different strategies.

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HEALTH RISKS

Although there are many possible definitions of “health risk”, it is defined here as “a factor that raises the probability of adverse health outcomes”. The number of such factors is countless.

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BURDEN OF DISEASE AND GLOBAL RISK FACTORS

Five leading risk factors identified in this report )childhood underweight, unsafe sex, alcohol use, unsafe water and sanitation, and high blood pressure( are responsible for one quarter of all deaths in the world, and one fifth of all DALYs.

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The leading global risks for mortality in the world are: High blood pressure )responsible for 13% of deaths globally(,

Tobacco use )9%(,

High blood glucose )6%(,

Physical inactivity )6%(, and

Overweight and obesity )5%(.

These risks are responsible for raising the risk of chronic diseases such as heart disease, diabetes and cancers. They affect countries across all income groups: high, middle and low.

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The leading global risks for burden of disease as measured in disability-adjusted life years )DALYs( are: Underweight )6% of global DALYs( and

Unsafe sex )5%(, followed by

Alcohol use )5%( and

Unsafe water, sanitation and hygiene )4%(.

Three of these risks particularly affect populations in low-income countries, especially in the regions of South-East Asia and sub-Saharan Africa. The fourth risk – alcohol use – shows a unique geographic and sex pattern, with its burden highest for men in Africa, in middle-income countries in the Americas and in some high-income countries.

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LIFE SPAN VS. HEALTH SPAN

Lifespan Number of years lived

Health Span Number of healthy years lived

We increasingly appreciate that disease and disability can significantly limit an individual's productivity and happiness and radically alter individual, family and community well being.

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EXAMINING “LIFESPAN” AND “HEALTH SPAN”

Impact on: “Lifespan” “Health Span”

% Total Deaths

Malnutrition 11.7 15.9

Cause % TotalDisability

Source: Murray CJL, Lopez AD. Science 1996

Malnutrition is responsible for approximately 12% of total deaths worldwide, radically altering global “lifespan,” but affects “health span” to an even greater degree, contributing nearly 16% of the world’s total disability.

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FOUR KEY DRIVERS OF RAPID CHANGES IN GLOBAL HEALTH PATTERNS

Demographic transition – increasing population size, substantial increase in the average age in most regions and falling death rates.

Cause of death transition – fraction of deaths or years of life lost shifting from communicable, maternal, neonatal and nutritional to non-communicable diseases and injuries despite the HIV epidemic.

Disability transition – steady shift to burden of disease from diseases that cause disability but not substantial mortality.

Risk transition – shift from risks related to poverty to behavioral risks.

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DRAMATIC DEMOGRAPHIC SHIFTS: MEAN AGE OFDEATH RISING RAPIDLY

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PERCENT OF DALYS FROM NON-COMMUNICABLE DISEASES IN2010

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THE RISK TRANSITION

As a country develops, the types of diseases that affect a population shift from primarily infectious, such as diarrhea and pneumonia, to primarily non-communicable, diseases such as cardiovascular disease and cancers. This shift is caused by: Improvements in medical care, which mean that children no longer

die from easily curable conditions such as diarrhea

The ageing of the population, because non-communicable diseases affect older adults at the highest rates

Public health interventions such as vaccinations and the provision of clean water and sanitation, which reduce the incidence of infectious diseases.

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THE RISK TRANSITION

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MAJOR RISK FACTORS

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MAJOR ATTRIBUTES OF DALY

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AGE DISTRIBUTION OF GLOBAL YLLS FOR THE YEAR 2011 USING VARIOUS LOSS FUNCTIONS

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DISTRIBUTION OF GLOBAL YLL FOR THE YEAR 2011

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CHANGING DISEASE BURDEN

Source: Murray CJL, Lopez AD. Science 1996;274:740–743

Changing Disease Burden1990–2020

Expected to DecreaseLower respiratory

infectionsDiarrheal diseasePerinatal conditionsMeaslesCongenital anomaliesMalariaMalnutritionAnemia

Expected to Increase

DepressionHeart diseaseCerebrovascular diseaseTraffic accidentsChronic obstructions/pulmonary diseaseWar, violence, suicideHIVLung cancer

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CHANGE IN 20 LEADING CAUSES OF YLD AT GLOBAL LEVELS, 2000 TO 2011

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CHANGE IN 20 LEADING CAUSES OF DALY AT GLOBAL LEVEL, 2000 TO 2011

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COMPARISON OF TOTAL DALYS FOR 15 MAJOR CAUSE GROUPS

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“The burden of disease is the great oppressor, perhaps the single greatest cause of loss of personal freedom. Now, more than any other time in human history, we can influence this great oppressor with our actions. We have it within our power to improve the health of people on the earth.” – John Seffrin, PhD

CEO, American Cancer Society

Understanding the Burden of Disease. The Pfizer Journal. 2000

THE GLOBAL BURDEN OF DISEASE

DALY & QALY

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DALY

The disability-adjusted life year )DALY( is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death.

DALY "extends the concept of potential years of life lost due to premature death...to include equivalent years of 'healthy' life lost by virtue of being in states of poor health or disability. In so doing, mortality and morbidity are combined into a single, common metric. One

“One year lost to poor health.”

Disability Adjusted Life Year

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DALY

A DALY is a health outcome measure with two main components Quality of life reduced due to a disability

Lifetime lost due to premature mortality

It is essential to understand what the DALY-concept measures and how it is constructed. Burden is measured along two dimensions: time lived with disability and time lost due to premature mortality.

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83 YEARS

NO DISABILITY

DALYS DUE TO LIVING WITH DISABILITY

Red area measures DALYs. Red + white is a “normal” life

Years lived with “disability”-YLD

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DALYS DUE TO LIVING WITH DISABILITY

The x-axis shows life expectancy for the 'normal' life. The "standardized" maximum life span, 83 years for females and 80 years for males, is taken from the country with the highest life expectancy in the world: Japan. The y-axis shows degree of disability. The 'normal' life is quantified as the total area in the box, a combination of the number of years lived and the quality of life, or degree of disability. From this ideal state of the world it is possible to calculate the burden of disease caused by premature death or disability.

If for example a girl aged 5 happens to become a victim of a mine explosion causing a below-knee amputation, and she does not die but is rehabilitated to a health state with some loss of physical functioning, her DALY loss could be depicted as the red area in the figure. Her loss is 78 years adjusted by a disability weight i. If this weight is, say, 0.3, her loss is 0.3 x 78 = 23.4.

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NO DISABILITY

83 YEARS

DALYS DUE TO EARLY DEATH

Red area measures DALYs. Red + white is a standard life

Years of life “lost”-YLL

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DALYS DUE TO EARLY DEATH

Premature death from a myocardial infarction, say at age 50, would produce the DALY-loss as depicted by the read area in the figure. This patient’s loss is 33 years. No adjustment is made for disability because the patient dies.

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YEARS OF LIFE LOST TO PRESENT DEATHS

Information required Age at death

Sex

Country / region

Estimating life expectancy Depends upon age, sex and region

Obtained in Global Burden of Disease life tables

Years of life lost = Life expectancy - age at death

Life expectancy

Death today

Life expectancy

Years of life lost

Survival today

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NO DISABILITY

83 YEARS

DALYS DUE TO DISABILITY AND PREMATURE DEATH COMBINED

This schematic illustration shows a woman who lives with a disability, for instance deafness from the age of 5 and dies prematurely at the age of 50.

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DALY = YLL + YLD

Traditionally, health liabilities were expressed using one measure: )expected or average number of( 'Years of Life Lost' )YLL(. This measure does not take the impact of disability into account, which can be expressed by: 'Years Lived with Disability' )YLD(. DALYs are calculated by taking the sum of these two components in a single formula: DALY = YLL + YLD.

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DALY=YLL)N X L(+YLD)I X DW X L(

The YLL basically correspond to the number of deaths multiplied by the standard life expectancy at the age at which death occurs. The basic formula for YLL is the following for a given cause, age and sex:

YLL = N x L

N = number of deaths L = standard life expectancy at age of death in years

To estimate YLD for a particular cause in a particular time period, the number of incident cases in that period is multiplied by the average duration of the disease and a weight factor that reflects the severity of the disease on a scale from 0 )perfect health( to 1 )dead(. The basic formula for YLD is the following )again, without applying social preferences(:

YLD = I x DW x L

I = number of incident cases DW = disability weight L = average duration of the case . . until remission or death )years(

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SAMPLE DALY CALCULATIONS DISEASES 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 82( + YLD )=100,000 x )7/365( x 0.3( = 164,000 + 575.3 = 164,600

B: YLL )= 100,000 x 3( + YLD )=100,000 x 2 x 0.6( = 300,000 + 120,000 = 420,000

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ONE DALY

The DALY relies on an acceptance that the most appropriate measure of the effects of chronic illness is time, both time lost due to premature death and time spent disabled by disease. One DALY, therefore, is equal to one year of healthy life lost.

One DALY can be thought of as one lost year of "healthy" life. The sum of these DALYs across the population, or the burden of disease, can be thought of as a measurement of the gap between current health status and an ideal health situation where the entire population lives to an advanced age, free of disease and disability.

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WORLD DALY

Age-standardized disability-adjusted life year )DALY( rates from All Causes by country )per 100,000 inhabitants(

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CHRONIC DISEASES, MAJOR CAUSE OF DALYS IN DEVELOPED WORLD-2020

Cause % Total DALY

All cardiovascular

18.6

All mental illness

15.4

All cancer

15.0

All respiratory

4.8

All alcohol

4.7

Source: Murray CJL, Lopez AD. Science 2006; 274:741

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DALY DOWNWARD SPIRAL

MalariaTuberculosisHIVDiarrheal DiseaseRespiratory Disease

CardiovascularDiabetes

CancerMental Illness

Clean WaterAdequate NutritionSanitationModern MachinerySafety and Security

High Calorie DietSmoking

Limited Exercise

DALY = DisabilityAdjusted Life Year

Communicable Diseases

Developing Country

EconomicIntervention

DALYs

Developed Country

DALYs

Chronic Diseases

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DALY EXAMPLE

Looking at the burden of disease via DALYs can reveal surprising things about a population's health. For example, the 1990 WHO report indicated that 5 of the 10 leading causes of disability were psychiatric conditions. Psychiatric and neurologic conditions account for 28% of all years lived with disability, but only 1.4% of all deaths and 1.1% of years of life lost. Thus, psychiatric disorders, while traditionally not regarded as a major epidemiological problem, are shown by consideration of disability years to have a huge impact on populations.

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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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SOME BASIC 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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SCHEMA FOR ASSESSING NON-FATAL HEALTH OUTCOMES

Disease Impairment Disability Handicap

Polio Paralyzed legs Inability to walk Unemployed

Brain injury Mild mental retardation Difficulty learning Social isolation

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DALYS AND QALYS

DALY is a modification of QALY )Quality Adjusted Life Years(. Both concepts combine information about length of life and quality of life.

A DALY is a negative QALY.

Whereas DALYs represent a loss and should be minimized, QALYs represent a gain and should be maximized.

In the DALY approach, the years are disability weighted on a scale from zero, which indicates perfect health )no disability(, to one, which indicates death.

In the QALY approach, the scale goes the opposite way: A quality weighting )sometimes called “utility”( of 1 indicates perfect health, whereas 0 indicates no quality of life, and is synonymous to death.

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QALY

The quality-adjusted life year or quality-adjusted life-year )QALY( is a measure of disease burden, including both the quality and the quantity of life lived.

The QALY is based on the number of years of life that would be added by the intervention. Each year in perfect health is assigned the value of 1.0 down to a value of 0.0 for being dead. If the extra years would not be lived in full health, for example if the patient would lose a limb, or be blind or have to use a wheelchair, then the extra life-years are given a value between 0 and 1 to account for this.

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QALY

QALY takes into account both the quantity and quality of life generated by healthcare interventions. It is the arithmetic product of life expectancy and a measure of the quality of the remaining life-years. A QALY places a weight on time in different health states. A year of perfect health is worth 1 and a year of less than perfect health is worth less than 1. Death is considered to be equivalent to 0; however, some health states may be considered worse than death and have negative scores.

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QALY

QALY considers the age at which the disease or death occurs and the duration and severity of any disability created. Basically the number of fully healthy life years lost to a particular disease or risk factor.

The QALY method helps us measure these factors so that we can compare different treatments for the same and different conditions. A QALY gives an idea of how many extra months or years of life of a reasonable quality a person might gain as a result of treatment )particularly important when considering treatments for chronic conditions(.

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QALY

A number of factors are considered when measuring someone's quality of life, in terms of their health. They include, for example, the level of pain the person is in, their mobility and their general mood. The quality of life rating can range from negative values below 0 )worst possible health( to 1 )the best possible health(.

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QALY

Having used the QALY measurement to compare how much someone's life can be extended and improved, we then consider cost effectiveness - that is, how much the drug or treatment costs per QALY. This is the cost of using the drugs to provide a year of the best quality of life available - it could be one person receiving one QALY, but is more likely to be a number of people receiving a proportion of a QALY - for example 20 people receiving 0.05 of a QALY.

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NO DISABILITY

83 YEARS

RELATION BETWEEN QALYS AND DALYS

DALYs = healthy years lost QALYs = healthy years gained

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GLOBAL BURDEN OF DISEASE AND AGING

The global burden of disease is a product of complex and interwoven demographic, economic, social, political, religious and environmental factors. Probably the strongest factor yielding the greatest impact on global “health span” is the aging of the world’s population.

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Population ageing is unprecedented, without parallel in human history—and the twenty-first century will witness even more rapid ageing than did the century just past.

Population ageing is pervasive, a global phenomenon affecting every man, woman and child—but countries are at very different stages of the process, and the pace of change differs greatly. Countries that started the process later will have less time to adjust.

Population ageing is enduring: we will not return to the young populations that our ancestors knew.

Population ageing has profound implications for many facets of human life

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The world population is rapidly ageing. Between 2000 and 2050, the proportion of the world's population over 60 years will double from about 11% to 22%. The absolute number of people aged 60 years and over is expected to increase from 605 million to 2 billion over the same period.

Around 4-6% of older persons in high-income countries have experienced some form of maltreatment at home.

25-30% of people aged 85 or older have some degree of cognitive decline.

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PERCENTAGE OF POPULATION AGED 60+, 2050

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PERCENTAGE OF POPULATION AGED <15, 2050

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This will make four and five generation families, with all their complexity and competing resource needs, the norm worldwide. It will also mean that chronic disease will dominate as sources of DALY’s. This is already the case in the developed world where cardio vascular disease accounts for 18.6% of lost health, mental illness results in 15.4% of lost health and cancer delivers 15% of lost health.

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AGING OF THE WORLD’S POPULATIONS

An Aging World Population...% Over 60

605M

2000

2000M

2050

…Means More Chronic Disease

2000

Cardiovascular 11.1% 14.7%

Cancer 5.1% 9.9%

Neuropsychiatric 10.5% 14.7%

2020

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REALITY OF AGING

The reality of aging is causing health policy experts to go back to the drawing board and consider the relationship between “lifespan” and “health span”. Stated in another way, when examining the application of health resources, experts have often focused on the first 15 years of life and the last 15 years.

But today, with the five-generation global family increasingly the norm, we have begun to appreciate that the health gains achieved in the first 15 years must be consolidated and leveraged to the benefit of the next 15 years, and so on up the ladder of life. Early and continuous investment delivers long-term gains.

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URBANIZATION

If aging is an undeniable reality, then so is urbanization. Rapid urbanization, with dense populations, unsafe water, poor sanitation and poverty, is a perfect breeding ground for disease. In 1950,only 1/3 of the global population resided in urban settings. By 2000, this number had risen to 45%. And by 2020, 60% of the world’s population is projected to be urban.

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PERCENT OF GLOBAL POPULATION IN URBAN AREAS

Rapid Urbanization with Dense Populations, Unsafe Water, Poor Sanitation, and Poverty Are a Perfect Breeding Ground for Disease

33%

1950

45%

2000

60%

2020

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INDUSTRIALIZATION AND URBANIZATION

Higher levels of obesity, diabetes and heart disease.

Smoking, high fat diets and poor exercise habits accompany industrialization and urbanization.

Dietary changes lead to:

Developed Nations:

Developing Nations:

Resources to challenge harmful changes

No resources to cope

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POVERTY: A BREEDING GROUND FOR COMPROMISED “LIFESPAN” AND “HEALTH SPAN”

“Poor people are often sick because they are poor, and sometimes poor people are poor because they are sick.” – Nils Daulaire, MD, PhD

President, Global Health Council

Source: Global Health Council

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PER CAPITA INCOME GAP

“There is a glass ceiling that globalization may hit early in the 21st century, which will require all of us to pay attention to the burden of disease faced by poor people.” Nils Daulaire, MD, MPH

President, Global Health Council

Source: Global Health Council

This in effect eliminates the potential of an individual to double his income over a 35-year period. And the gap between rich and poor is growing. In 1900,the per capita income gap between the richest 20% and the poorest 20% was 25 to one. In 2000, that gap was 67 to one.

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LOW-AND MIDDLE-INCOME COUNTRIES

global burden of disease and health policy

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