The Epidemiology of Chronic Diseases: an Overview

The Epidemiology of Chronic Diseases: An

Overview

Introduction

That you have chosen this module suggests that you recognize the burden associated with chronic diseases. We will start this unit by describing what chronic non communicable diseases are. We will then look at how big the problem of chronic diseases is globally - in developed and developing countries, highlighting its scale in sub-Saharan Africa in general and Southern Africa in particular.

There are THREE sessions in this unit.

Study Session 1: An introduction to epidemiology and implication of chronic non communicable diseases

Study Session 2: Demographic, epidemiological and nutrition transition

Study Session 3: Social Determinants for non communicable diseases

In session 1 we explain what chronic diseases are, and the diseases that fall into this category. We also start to develop an overview of why they are a concern. We also highlight the burden associated with chronic disease globally and in developing countries, dispelling assumptions that certain parts of the world are completely unaffected by chronic diseases. Basic concepts in chronic disease epidemiology are also defined.

In session 2, we discuss demographic, epidemiological and nutrition transition and how these relate to the development of chronic diseases.

In session 3, we look at how social determinants of health are associated with non communicable diseases

Unit 1 - Session 1

Introduction: Epidemiology and implications of Chronic Non Communicable Diseases

Contents

1. Learning outcomes of this session
2. Readings
3. Defining chronic disease
4. How big is the problem of chronic diseases?
5. Who is affected by chronic diseases?
6. Burdens associated with chronic diseases
7. The impact of chronic diseases on health services
8. Session summary

Timing of this session

There are four readings and seven tasks in this session. It should take you about two hours to complete.

1LEARNING OUTCOMES OF SESSION 1

• Explain the terms ‘chronic diseases’ and chronic non communicable disease
• Describe the extent of the problem.
• Explain why chronic diseases are a concern.
• Understand the global and local burden of chronic diseases.
• Understand basic concepts in chronic disease epidemiology.

• Understand the implication of these chronic diseases in relation to health and development at the global, country and family level

• Understand the basic epidemiological concepts related to chronic diseases
• Make a reasonable argument why chronic diseases are a concern globally

2.READINGS

There are four relevant readings for this session.

3DEFINING CHRONIC DISEASE

TASK 1 – Develop your own definition of chronic diseases

(a)As health workers, we encounter many different types of diseases: in your understanding, what is a ‘chronic disease’?

(b)What conditions fall within the category of ‘chronic disease’? List a few that you know of.

FEEDBACK

(a) According to the World health Organisation, chronic diseases are diseases of long duration and generally slow progression. So once someone has the condition they will have to manage and control it. Although HIV and AIDS will not be discussed in this module, it is important to note that this disease is also chronic. However in this module we will be discussing chronic diseases that are ‘non communicable’. Non communicable means non infectious; therefore the conditions that we will be referring to in this module are non infectious. Internationally, these diseases are also referred to as ‘non communicable diseases’ or ‘degenerative diseases’.

(b) Chronic diseases include cancers, diabetes, hypertension and chronic respiratory diseases such as emphysema. All these are non communicable diseases. As mentioned, HIV and AIDS is also chronic; however it can be transmitted from one person to the next.

A definition of chronic disease

Chronic diseases have been defined as diseases that have “a prolonged course, do not resolve spontaneously and for which a complete cure is rarely achieved” (Brownson et al, 1998). These are some of their major features:

They have an uncertain etiology: no direct causes have been identified for the emergence of these diseases; studies show relationships between the emergence of the disease and exposure to certain factors referred to as ‘risk factors’. A cluster of factors, such as the ones mentioned above, are shown to have a strong predictive relationship to these diseases, even if exposure to these factors does not necessarily lead to such disease; for the chronic diseases we are focusing on, major risk factors relate to life conditions and practices. This is one of the major contributions of the field of epidemiology - establishing causal relationships between the emergence of the disease and factors that the affected persons have been exposed to.

- They have multiple risk factors: unlike most infectious diseases they result from exposure to several risk factors;

- They have a long latency period: the disease proceeds over a long course of time without symptoms;

- They show a prolonged course of illness;

- They are generally non-contagious in origin;

- They result in functional impairment or disability;

- They are incurable;

- They require long-term and systematic approach to treatment.

Do the conditions you identified have these characteristics? Can we add any more characteristics to this list?

TASK 2: Identify some of the implications of the burden of chronic disease

The definitions above present a picture of the nature of chronic disease. What then might be the implications of chronic disease?

• What costs or losses might a chronic disease predispose one to? Think of costs, or the burden of suffering that chronic disease presents individuals, families and the society at large. You may categorise your response according to these affected populations.
• What opportunities does this picture show us for arresting the course of disease?

FEEDBACK

Key issues to consider include the length of time the illness is present (a lifetime burden); the implication of learning to live with the disease; the absence of a known direct cause, which implies a more wide-ranging approach in treatment and prevention; the possibility of living with the disease without knowing that one is affected; a high cost of treatment is implied, as well as a lifelong systematic approach to containing the course of the disease. There is a measure of containment in this type of disease, since they are not infectious. And on the positive side, there is the fact that something is known about the predisposing factors; this might show an opportunity, a gap, for fighting the disease.

As we have mentioned, we shall mainly focus on the cluster of diseases that in the past were referred to as ‘diseases of lifestyle’ due to the apparent relationship of the disease to behavioural patterns. This phrase is out of favour nowadays in recognition of the fact that ‘blaming the victim’ does not take adequate account of the wide range of predisposing risk factors, some of which have their roots in the environments of the affected.

4HOW BIG IS THE PROBLEM OF CHRONIC DISEASE?

It is estimated that a total of 57 million deaths occurred worldwide during 2008 and 63% of these deaths were due to NCDs, principally cardiovascular diseases, diabetes, cancer and chronic respiratory diseases. In addition, a majority of these NCD deaths (80%) occurred in low- and middle-income countries.

The World Health Organization projects that NCDs will be responsible for a drastically increased total number of deaths in the next decade. It was projected that NCD deaths will increase by 15% globally between 2010 and 2020, resulting in 44 million deaths. It is said that the greatest increases will occur in the WHO regions of Africa, South-East Asia and the Eastern Mediterranean, where they will increase by over 20 % (Global status report on non communicable diseases

2010)

Figure 1: Total deaths by broad cause group, by WHO Region, World Bank income group and by sex, 2008 (Source, WHO, 2011)

If one looks carefully at these chronic NCD deaths you will find that cardio- vascular diseases followed by cancers are the biggest contributors of NCD deaths amongst those under the age of 70, as shown figure 2 on the next page.

Figure 2: Proportion of global NCD deaths under the age of 70, by cause of death, 2008

(Source, WHO, 2011)

Read the following text, which gives more detail about Fig. 2.

READING

World Health Organisation. (2010). Ch 1 - Burden: mortality, morbidity and risk factors. Global Status Report on Non-communicable Diseases 2010. Geneva: WHO: 9-32.

Now do the next reading, followed by Task 3.

READING

World Health Organisation. (2011). Non-communicable Diseases Country Profiles 2011. Geneva: WHO: 1-30.

TASK 3: Identify prevalent chronic diseases

Now that you have an overview on chronic diseases, refer to the NCD country profile 2011 presented by WHO to answer the following questions:

 What chronic NCDs are prevalent in your country / community?

 Prioritize them from the most urgent to the least urgent.

 How does your country compare to other countries within the same income group?

FEEDBACK

This task begins to address the questions presented in Assignment 1.

5 WHO IS AFFECTED BY CHRONIC DISEASES?

TASK 4: Evaluate a statement about chronic diseases

Consider this statement: ‘Chronic diseases are diseases of affluence’

Now that you have looked at the magnitude of chronic NCDs, take time to try and understand the route through which chronic diseases manifest themselves in communities. Reflect on the statement above and answer the following questions, after reading the section below:

• Can chronic NCDs really still be considered ‘diseases of affluence’?
• Do chronic NCDs only affect rich countries?
• Do chronic NCDs affect only the rich in rich countries?
• Are chronic NCDs a problem only for the elderly?

Advances in medical technology have resulted in people living longer and therefore the ageing population increases. In many parts of the world, especially developed countries such as Sweden where they have high proportion of ageing population, the prevalence of NCDs tends to be higher.

Previously Chronic NCDs were known as diseases of affluence. However, current data shows that low- and middle-income countries now have the highest mortality rates due to NCDs, which suggests a change in NCD trends. Vulnerable and disadvantaged communities also tend to have lower life expectancy than people from higher social classes – determined by education, occupation, income, gender and ethnicity.

Figure 1 shows this phenomenon explicitly. The question is why are we observing this trend? Session 4 in Unit 1 will show the factors that are propelling this trend. The drivers include globalisation, urbanisation and physical inactivity, to name a few. For example in South Africa black urban women have the highest prevalence of obesity which puts them at risk of NCDs.

6BURDENS ASSOCIATED WITH CHRONIC DISEASES

Chronic NCDs have been said to place a burden on individuals, families, health systems and the economy, brought about by loss of independence, loss of income, increased budget for medication and loss of economically active workforce.

After reading the following text about the economic effects of chronic disease, answer the questions in the task below:

READING

Suhrcke, M., Nugent, R.A., Stuckler, D. & Rocco, L. (2006). Chapter 3: Economic consequences of chronic diseases. Chronic Disease: An economic perspective. London: Oxford Health Alliance: 17-29. You will find this chapter in your Reader. The whole publication is on your DVD.

TASK 5: Consider the costs and effects of chronic diseases

1. What have the authors listed as direct, indirect and intangible cost of chronic diseases?

2. What are the effects of chronic diseases on labour supply and productivity

(workforce)?

Effects on the individual and family

People living with chronic diseases are affected socially and economically. Chronic disease has major adverse effects on the quality of life of affected individuals; it causes premature death, creates significant adverse, and underappreciated, economic effects on families, communities and societies in general.

Effects on the workforce

In Tough Choice: Investing in Health for Development, the World Health Organisation warns of some of the risks posed by NCDs, and consequent higher morbidity levels:

Increased morbidity will also reduce productivity and limit individuals’ capacity to participate in the labour force. Coping mechanisms - such as removing young girls from education to care for a sick family member – should also be factored into the cost (WHO: 118).

Chronic diseases have not only social, but also economic effects. A significant proportion of affected people are those of working age – family breadwinners and people who should be productive members of the economy. In addition, in the case of chronic disease there is a need for regular visits to the health facility, which impacts on time at work, and productivity. Healthier individuals are less likely to be absent from work.

TASK 6: Think about the burden of chronic diseases

Think of people that you have seen with any of the chronic NCDs. Think about the effect these diseases have on the individual, family, society and health services.

• Make brief notes under the following headings:

-Effects on the individual

-Effects on the family

-Effects on the health services

• Discuss the coping mechanisms you see occurring within families and the working environment, to withstand the conditions brought about by the burden of chronic diseases in your area.

FEEDBACK

Compare your notes with the points made in this reading.

READING

World Health Organization. (2005). The Economic Impact of Chronic Diseases. Preventing Chronic Diseases: A vital investment. Geneva: WHO: 74-79

7THE IMPACT OF CHRONIC DISEASES ON HEALTH SERVICES

Chronic diseases threaten to overwhelm already over-stretched health services. While historically the health care system has focussed on treating acute illnesses, today there is growing pressure for the health care system to effectively manage the increasing number of chronic disease sufferers as well. Chronic conditions are long-term illnesses that limit life activities and require ongoing care. Yet many people do not have access to ongoing medical attention, especially in developing countries, and particularly in the African region where resources are scarce. Lives are then lost due to the fact that acute care models and available services cannot accommodate the needs of chronically ill individuals. These are often people from the most needy groups, where the result is further increased stress on families due to loss of breadwinners.

TASK 7: Consider the case of South African health services

Bearing in mind the strain on health services brought about by the burden of chronic diseases, explain the South African health service status within a developing country, and highlight how you see health systems accommodating people from different socio-economic statuses (especially the poor).

Feedback

Compare your answers with the WHO article, Tough Choices: Investing in health for development.

8SESSION SUMMARY

In this session we have introduced you to chronic diseases and defined related concepts. In addition we have looked at the magnitude of chronic NCDs and the people affected by these conditions. We have further highlighted the global spread of NCDs dispelling assumptions that certain parts of the world are completely unaffected by chronic NCDs. We have looked at the implications or consequences of chronic NCDs. Consequences of NCDs include its effects on the individuals, families, the workforce and the health services.

Unit 1 - Session 2

Demographic, epidemiological and nutrition transition

Introduction

The main concerns in developing countries have always been the high prevalence of health problems traditionally associated with poverty and under-development such as nutritional, peri-natal, maternal and infectious diseases which lead to high mortality rates. With increasing urbanization, and the concomitant changes in life circumstances (including dietary, physical activities and social habits), the prevalence of chronic diseases like non-insulin-dependent (type II) diabetes mellitus (NIDDM), hypertension and cardiovascular diseases have increased in the developing world. The result is that in the last few decades, there have been major health changes in developing countries. These changes have been described as the demographic, epidemiological and nutrition transition.

In this session the terms will be explained.

Contents

1.Learning outcomes of this session

2.Readings

3.Demographic, epidemiological and nutrition transition

4.Session summary

Timing of this session

In this session there are four readings and one task. It should take you at least one hour to finish the session.