This discussion focuses on the concept of disease burden, which you will learn about in-depth in Chapter 3 of the eText attached.? For this discussion, in addition to Chapter 3, ?plea

17 Sep This discussion focuses on the concept of disease burden, which you will learn about in-depth in Chapter 3 of the eText attached.? For this discussion, in addition to Chapter 3, ?plea

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This discussion focuses on the concept of disease burden, which you will learn about in-depth in Chapter 3 of the eText attached.

For this discussion, in addition to Chapter 3, please refer to the "Global burden of 87 risk factors in 204 countries and territories" article provided in the Module 2 Learning Resources folder. Read the article summary and peruse the article.

This is a one-page perusal of both articles to answer the three questions below.

1) What information presented in this article was most surprising to you about disease burden?

2) Why was that information surprising?

3) In your own words, explain how disease burden is measured and how it is used to define global health.

Global Health Metrics

www.thelancet.com Vol 396 October 17, 2020 1223

Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019 GBD 2019 Risk Factors Collaborators*

Summary Background Rigorous analysis of levels and trends in exposure to leading risk factors and quantification of their effect on human health are important to identify where public health is making progress and in which cases current efforts are inadequate. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a standardised and comprehensive assessment of the magnitude of risk factor exposure, relative risk, and attributable burden of disease.

Methods GBD 2019 estimated attributable mortality, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs) for 87 risk factors and combinations of risk factors, at the global level, regionally, and for 204 countries and territories. GBD uses a hierarchical list of risk factors so that specific risk factors (eg, sodium intake), and related aggregates (eg, diet quality), are both evaluated. This method has six analytical steps. (1) We included 560 risk–outcome pairs that met criteria for convincing or probable evidence on the basis of research studies. 12 risk–outcome pairs included in GBD 2017 no longer met inclusion criteria and 47 risk–outcome pairs for risks already included in GBD 2017 were added based on new evidence. (2) Relative risks were estimated as a function of exposure based on published systematic reviews, 81 systematic reviews done for GBD 2019, an

Courtesy of Mark Tuschman.

Skolnik, Richard. Global Health 101, Jones & Bartlett Learning, LLC, 2019. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/indianatech-ebooks/detail.action?docID=5894023. Created from indianatech-ebooks on 2022-09-15 00:20:57.

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CHAPTER 3 The Global Burden of Disease

LEARNING OBJECTIVES

By the end of this chapter, the reader will be able to do the following:

■ Discuss the concepts of health-adjusted life expectancy (HALE), disability-adjusted life years (DALYs), and the burden of disease

■ Describe the leading causes of disability, deaths, and DALYs by region, country income group, age, and sex

■ Describe the leading risk factors for disability, deaths, and DALYs by region, country income group, age, and sex

■ Discuss the demographic and epidemiologic transitions

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P ▶ Vignettes

rincess is a 3-year-old girl who lives near the town of Kenema in Sierra Leone. Although Sierra Leone has made

some progress in reducing young child death, the country remains very poor, still suffers from the ravages of its earlier civil war, and continues to have a very weak health system. Access to safe water and sanitation and good knowledge of hygiene are also limited. The burden of malaria has gone down, but the disease is still very prevalent. What are the leading causes of death for young children like Princess? What are the most important risk factors for those causes? Is there good evidence about what can be done in cost-effective and fair ways to reduce the burden of deaths among young children in Sierra Leone and similar countries?

Aisha is a 50-year-old woman who lives in the northern part of Nigeria. She is from a lower middle-class family, in an area that is still quite poor. Aisha has been feeling unwell and recently visited the outpatient clinic at the regional hospital. The check-up and tests the doctors carried out indicated that she has high blood pressure, high cholesterol, and diabetes. The doctors prescribed medicines for her to reduce her blood pressure and cholesterol and another drug to lower her blood sugar. As Aisha returned home, she thought about how people’s health had changed in the last decade in her town. Earlier, she rarely heard about the conditions with which she had been diagnosed. Now, however, it seemed like many of her friends had been diagnosed with the same problems.

Jose is a 30-year-old man in Bolivia. He is from an indigenous, relatively poor community in the highlands. Two decades ago, Jose’s community still faced many child deaths, especially from

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pneumonia and diarrhea. The community also had a substantial burden of undernutrition and tuberculosis (TB). To what extent have such causes of death declined in Jose’s community? If so, what are the leading causes of death now? Is there a “convergence” between the leading causes of death in Jose’s community and the lowland communities populated mostly by people of European descent?

Shireen is a 22-year-old woman in Bangladesh. She is just starting a family. Her mother and grandmother have given her advice about when to have her first child and where to get and how to use family planning methods. They have also suggested that she should have only two children and that she should space them 3 or more years apart. A community health worker has been in touch with Shireen regularly and has made the same suggestions as her mother and grandmother. In Bangladesh in 1960, women had on average more than six children and the median age of the population was around 19 years of age. In 2016, women had on average just over two children and the median age of the population was around 26 years of age. What causes these shifts? Do they occur consistently as countries develop socially and economically? What will the age distribution of the population look like in Bangladesh in 25 years and why?

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▶ Measuring the Burden of Disease The World Health Organization (WHO) defines health as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.” Those who work on global health have attempted for a number of years to construct a single indicator that could be used to compare how far different countries are from the state of good health. Ideally, such an index would take account of morbidity, mortality, and disability; allow one to calculate the index by age, by gender, and by region; and allow one to make comparisons of health status across regions within a country and across countries. This kind of index would measure what is generally referred to as the burden of disease.

One such indicator is health-adjusted life expectancy, or HALE. This is a health expectancy measure. HALE is the number of years a person of a given age can expect to live in good health, taking account of mortality and disability. This can also be seen as “the equivalent number of years in full health that a newborn can expect to live, based on current rates of ill health and mortality.” To calculate HALE, “the years of ill health are weighted according to severity and subtracted from the overall life expectancy.”

TABLE 3-1 shows life expectancy at birth in 2016 for a number of low-, middle-, and high-income countries and how it compares with HALEs for those countries in the same year, for males and females. In principle, each country should strive to help its people live as long and as healthy as possible. In that case, health- adjusted life expectancy and life expectancy at birth would converge at a relatively high number.

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TABLE 3-1 Life Expectancy at Birth and Health-Adjusted Life Expectancy by Sex, Selected Countries, 2016

The composite indicator of health status that is most commonly used in global health work is called the disability-adjusted life year, or DALY. This indicator was first used in conjunction with the 1993 World Development Report of the World Bank and is a health gap measure. It is now used consistently in burden of disease studies. In the simplest terms, a DALY is “the sum of years lost due to premature death (YLLs) and years lived with disability (YLDs). DALYs are also defined as years of healthy life lost.”

The calculation of years lost to premature death is based on the difference between the age at which one dies and one’s life expectancy at that age. To make this calculation, those involved in the key studies on the global burden of disease have constructed

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a reference standard life table that takes account of the highest life expectancy at birth globally. For the 2016 study, this was set at 86.6 years. This life table is used to calculate premature death for

all countries in the study.

One might ask why the study is not based on life tables for each individual country. In very simple terms, one could respond by noting that, in principle, any death before the life expectancy of the people who live the longest globally is “premature.” One might also add that in order to make the world a healthier place, a goal must be to have people live “as long as possible,” rather than live only as long as they live now.

FIGURE 3-1 illustrates the calculation of years of life lost due to premature death for three different scenarios.

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FIGURE 3-1 Calculating Years of Life Lost (YLLs) Due to Premature Death

Adapted with permission from Session 6, Module 2 of Essentials of Global Health,

Coursera/Yale University, 2016. Data from Institute of Health Metrics and Evaluation

(IHME). (n.d.). Global Burden of Disease Study 2016 (GBD 2016) data resources:

GBD 2016 reference life table. Retrieved from http://ghdx.healthdata.org/gbd-2016

As noted in Figure 3-1, if a newborn were to die in Liberia, for example, that newborn would have suffered 87 years of life lost due to premature death. Life expectancy at 40 according to the reference life tables is 87, or 47 more years. Thus, if a 40-year-old woman in Malawi were to die in a car accident, she would have

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http://ghdx.healthdata.org/gbd-2016

suffered 47 years of life lost due to premature death. Life expectancy at 60 years of age according to the standard reference life table is 88, or 28 more years. Thus, if a French male were to die of a heart attack at age 60, he would have suffered 28 years of life lost.

The value for years lived with disability is calculated by weighting these years by a disability index. For the Global Burden of Disease Study 2010, 14,000 people were surveyed directly and 16,000 people were involved via the internet in establishing disability weights. The disability weights used in the 2016 study were based on the 2010 weights, supplemented by data gathered from additional surveys done for the 2013 GBD study. The study authors also made some additional refinements to these weights, especially as they related to the severity of different health conditions.

FIGURE 3-2 illustrates the disability weights for five different conditions. It also shows model calculations of years of life lived with disability (YLDs) for three scenarios of people living with disability.

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FIGURE 3-2 Calculating Years Lived with Disability (YLDs)

Adapted with permission from Session 6, Module 2 of Essentials of Global Health,

Coursera/Yale University, 2016. Data from Salomon, J. A, Haagsma, J. A., Davis, A.,

de Noordhout, C. M., Polinder, S., Havelaar, A. H., . . . Vos, T. (2015). Disability

weights for the Global Burden of Disease 2013 study. Lancet Global Health, 3(11),

e712–e723.

As noted in Figure 3-2, let’s say that a person in Tanzania lives 30 years with a disability that has been given a weight of 0.10. In this case the person suffers 3 years of life lived with disability, equal to the number of years lived with disability, multiplied by the weight of

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that disability. If a person in France lived 20 years with a disability that has a weight of 0.25, then that person would have suffered the equivalent of 5 years lived with disability. If a person in Sri Lanka lived 10 years with a disability that has a weight of 0.5, then that person would have suffered 5 years of life lived with disability.

As noted earlier, a DALY is the sum of years of life lost due to premature death (YLL) and years of life lost due to disability (YLD). FIGURE 3-3 illustrates the calculation of a DALY for two different scenarios.

FIGURE 3-3 Calculating Disability-Adjusted Life Years (DALYs)

Adapted with permission from Session 6, Module 2 of Essentials of Global Health,

Coursera/Yale University, 2016.

As you can see in Figure 3-3, Person A dies at 50 years of age of drug-resistant tuberculosis, after living 3 years with this condition. In this case, the person’s life expectancy at 50 was 87. Thus the

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person suffered a loss of 37 years of life due to premature death. The disability weight for multidrug-resistant TB is 0.333. Thus, the person would have suffered 1 year of life lived with disability. The total DALYs for this person would be 37 plus 1, or 38.

Person B dies at 65 after living 10 years with moderate disability brought on by a stroke. This person died 23 years prematurely. This person also suffered about 3 years of life lived with disability. The total DALYs associated with this person would be 23 YLLs, plus 3 YLDs, or about 26 years.

A society that has more premature death, illness, and disability has more DALYs per person in the population than a society that is healthier and has less premature death, illness, and disability. One of the goals of health policy is to avert these DALYs in the most cost-efficient and fair manner possible. If, for example, a society has many hundreds of thousands of DALYs due to malaria that are not diagnosed and treated in a timely and proper manner, what steps can be taken to avert those DALYs at the lowest cost and in the fairest ways?

An important point to remember when considering DALYs, compared to measuring deaths, is that DALYs take account of periods in which people are living with disability. By doing this, DALYs and other composite indicators try to give a better estimate of the true health of a population instead of measuring deaths alone. This is easy to understand. Contrary to most popular belief, mental health problems, for example, are associated with an important number of deaths. However, they may also cause an enormous amount of disability. Several parasitic infections, such as schistosomiasis, cause very few deaths but large amounts of illness and disability. If we measured the health of a population with an important burden of schistosomiasis and mental illness only by measuring deaths, we would miss a major component of morbidity and disability and would seriously overestimate the

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health of that population. The next section elaborates on the concept of DALYs and how DALYs compare to deaths for a number of health conditions.

A number of critiques of DALYs have been written. Nonetheless, this text repeatedly refers to DALYs because this measure is so extensively used in global health work. In addition, a considerable amount of important analysis has been carried out that is based on the use of DALYs for measuring overall health status and assessing the most cost-effective approaches to dealing with various health problems.

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▶ Burden of Disease Data As you start a review of global health, it is important to get a clear picture of the leading causes of illness, disability, and death in the world. It is also very important to understand how they vary by age, sex, ethnicity, and socioeconomic status, both within and across countries. Additionally, it is essential to understand how these causes have varied over time and how they might change in the future. These topics are examined next.

Much of the data that follows on the burden of disease and risk factors is based on the findings of the Global Burden of Disease Study 2016, published in The Lancet in September 2017. The Institute of Health Metrics and Evaluation (IHME) coordinated that study. Those interested in the study methods may wish to consult the study directly. This chapter also heavily uses data from interactive data visualizations that the IHME has posted on its website. The reader should note that, while some data refer to “deaths” and some data refer to “DALYs,” references to the “burden of disease” refer to DALYs.

Wherever possible, data are shown by World Bank region or World Bank country income group. However, readers should be aware that the IHME data can be categorized into a range of regional groupings and by groups that are listed according to their ranking on a composite “social and economic development index” developed by the IHME.

Earlier burden of disease studies placed causes of deaths and DALYs into three categories:

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Group I—Communicable, maternal, and perinatal conditions (meaning in the first week after birth) and nutritional disorders

Group II—Noncommunicable diseases

Group III—Injuries, including, among other things, road traffic accidents, falls, self-inflicted injuries, and violence

The Global Burden of Disease Study 2016 does not use the groupings as they had been used earlier. Nonetheless, such groupings can be valuable to those who are new to the study of the burden of disease. Thus, they are used occasionally here.

Overview of Patterns and Trends in the Burden of Disease Understanding the patterns and trends in the burden of disease is central to understanding and dealing with key issues in global health. Some of the main findings of the burden of disease studies are summarized here :

■ People in much of the world are living longer than before. ■ Globally, women live longer than men by about 5 years on

average. ■ In the last 4 decades, there have been significant declines in

communicable, maternal, neonatal, and nutritional causes of death.

■ Globally, mortality rates have decreased for all age groups, with very substantial decreases for children under 5 years of age.

■ Nonetheless, there are substantial differences in the rate of mortality decrease across countries.

■ The years of life lost due to premature death are increasing for diabetes, some cancers, and, in some places, for drug use

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disorders, conflict, and terrorism. ■ The burden of disease is predominantly noncommunicable in

all World Bank regions and for all World Bank country income groups, except sub-Saharan Africa and low-income countries.

■ Over the last few decades, the burden of disease has shifted increasingly toward noncommunicable diseases in all World Bank regions and for all country income groups.

■ This shift has been fueled by, among other things, a reduction in communicable diseases and the aging of populations.

■ The 10 leading causes of total YLLs in 2016 were

17 Sep This discussion focuses on the concept of disease burden, which you will learn about in-depth in Chapter 3 of the eText attached.? For this discussion, in addition to Chapter 3, ?plea

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