Public Health and Epidemiology at a Glance

Margaret Somerville, K. Kumaran, Rob Anderson

• Editorial: Wiley-Blackwell
• Año: 2016
• ISBN:
  9781118999349
• Edición: 2
• Categoría: Medicine
• Categoría: Public Health, Administration & Care

First Prize in Public health in the 2017 BMA Medical Book Awards

Public Health and Epidemiology at a Glance is a highly visual introduction to the key concepts and major themes of population health. With comprehensive coverage of all the core topics covered at medical school, it helps students understand the determinants of health and their study, from personal lifestyle choices and behaviour, to environmental, social and economic factors. This fully updated new edition features:
•More coverage of audit and quality improvement techniques
•Brand new sections on maternal and child health, and health of older people
•New chapters on social determinants of health and guideline development
•Expanded self-assessment material This accessible guide is an invaluable resource for medical and healthcare students, junior doctors, and those preparing for a career in epidemiology and public health

Part 1
Introduction

1 Introduction to public health 2

2 Public health old and new 4

Chapter 1
Introduction to public health

What is public health? Why do I need to study it? We hear this question a lot from medical students just starting out on their medical careers. There is, of course, the standard definition:

Public health is the science and art of preventing disease, promoting health and well-being and prolonging life through the organised efforts of society (Faculty of Public Health)

…but what does this really mean?

The difference between the clinical and public health roles of doctors (and health services) is often illustrated by the image of people pulling others out of a river (Figure 1a). So busy are these people with saving those who are drowning that nobody has thought to go back upstream to find out why people are falling in to begin with. Public health aims to go upstream to find out why people are drowning. Besides understanding the problem, public health also tries to prevent it or reduce the harm resulting from it. Such action may involve persuading decision-makers to put up effective barriers to stop people falling into the river, repairing damaged river banks or controlling flooding, as well as providing information in the right way to prevent risky behaviour near the river. It may also be appropriate to make sure that the people saving those who are drowning are well trained and at the right place on the river bank to save as many lives as possible effectively and efficiently.

Doctors and other healthcare professionals spend their time dealing with people with health problems – those drowning people – and in treating individuals as effectively as possible. But many individuals' ability to obtain and follow medical advice is limited by circumstances outside their control. They may not be able to get to a clinic or hospital or afford the tests, drugs or other treatment once there; they may not understand the advice or treatment because of educational, language or cultural barriers, or may find it impossible to follow because of their domestic or social circumstances. Understanding these ‘upstream’ determinants of health is vital to providing health services that are sensitive to people's needs and effective in improving health. Methods of addressing them include legislation (e.g. wearing seat belts or motorcycle helmets), fiscal policy (e.g. taxing alcohol and tobacco), local and national social initiatives (e.g. literacy programmes, housing improvements and cycle paths) as well as more specific disease prevention programmes (e.g. immunisation). Taking such action requires a very different approach from that of the traditional healer, one that recognises that doctors and healthcare professionals may not be able to act directly themselves, but can work with and influence others to take action to improve health. It involves working with many different people, professionals, organisations and communities both within and outside the health sector.

There can be tensions between the traditional clinical approach to individuals' health problems and this population approach: what leads to improvement in the health of a population as a whole may not mean health improvement for every individual within it. Conversely, doing what is clinically best for the individual patient may mean others are excluded from getting appropriate, or even any, healthcare. Getting this balance as right as possible is a public health concern.

So public health is not just about acquiring a detailed knowledge base or a specific set of skills, it is also about an approach to health and health problems that is population-based, rational, transparent and fair. The public health approach seeks to identify and quantify health problems at a population or community level and then develop, introduce and evaluate interventions to improve health, monitoring progress to see whether the actions have made a difference. Epidemiology, the study of disease patterns, is the key discipline that helps us to understand population health, but in order to fulfil the role set out in the previous sentence, public health needs to draw on a wide range of other disciplines and knowledge. Statistics, sociology, psychology, health economics, health promotion, management and leadership, health systems and policy all contribute to the public health approach. This book attempts to give you an introduction to this complex and fascinating subject, which is fundamental to the good practice of medicine.

Domains of public health

The scope of public health, as described earlier, is very wide ranging, but is generally recognised as falling into three domains (Figure 1b). All three domains draw on the academic disciplines listed here and all collect or make use of information relevant to health, such as population data from the census, data on health service use (e.g. prescribed drugs, hospital admissions or consultations with health professionals), registrations of births and deaths, and disease and risk factor prevalence levels (e.g. alcohol consumption or diabetes).

• Health protection covers communicable diseases and environmental hazards, such as exposure to toxic chemicals and poisons. Exposure to hazardous substances at work is covered by the separate discipline of occupational medicine.
• Health improvement includes understanding the wider determinants of health, such as housing, education, poverty and lifestyle risk factors and seeks to improve health through health promotion and disease prevention.
• Improving services is concerned with how the quality of health services can be improved through evidence-based planning, the provision of effective and cost-effective treatment and ensuring that services are available to everyone who can benefit from them.

In the first section of this book (Chapters 3–14), we cover the main epidemiological concepts and methods that underpin evidence-based practice, whether public health or clinically focussed. The second section (Chapters 15–26) covers the types and sources of information used to assess population health status and need for healthcare. The third section (Chapters 27–35) covers health improvement and the final two sections health economics (Chapters 36–39) and health services (Chapters 40–43).

Chapter 2
Public health old and new

The last chapter described the scope of public health practice today, and how actions to improve public health include societal interventions such as legislation, taxation and infrastructure as well as providing healthcare and behavioural modification. Many of these actions are not new: ancient civilisations, such as the Romans, provided water and sanitation as part of the civic state and the Venetians and others instituted quarantine measures to prevent the spread of infectious diseases, particularly plague (Figure 2a).

In the United Kingdom, the Poor Law had provided for the poor and sick since medieval times. However, by the early nineteenth century, the urban poor, whose numbers had grown during the Industrial Revolution, were living in appalling conditions. Their plight was well described and quantified by Edwin Chadwick, whose report in 1842 (The Sanitary Condition of the Labouring Population) attributed their poor health and low life expectancy to their insanitary living conditions. These findings led to the 1848 Public Health Act, which set up a General Board of Health and local sanitary authorities with powers to provide pure water, effective sewage disposal and improve housing. The first Medical Officer of Health was appointed in Liverpool in 1847 and other cities soon followed.

Major epidemics of communicable disease were a feature of urban life in the nineteenth century. John Snow mapped cases of cholera in Soho in London in 1854 and showed that the people who lived closest to a particular water pump in Broad Street were the ones most likely to get the disease (Figure 2b). Legend has it that, when he failed to persuade the authorities to stop the pump being used, he removed the pump handle himself to prevent its use. John Snow's work, alongside that of William Farr, led to the development of epidemiology, the science that investigates disease patterns. Despite a growing acceptance that drinking water contaminated with raw sewage was the likely cause of cholera outbreaks, it took the ‘great stink’ of 1858 to make legislators agree to providing an adequate sewer system for London. Bazalgette's scheme was not completed until the 1870s and is still functioning today.

These interventions led to improvements in the health of the population, particularly reducing infant mortality, before the microbiological cause of cholera and other epidemics was known: Robert Koch identified the organism that causes cholera (Vibrio cholerae) in 1882. His work on micro-organisms, particularly the tubercle bacillus, led to the germ theory of disease replacing the earlier miasmic theory, which attributed disease to bad air. From providing social interventions to prevent disease, public health action now also focussed on individuals and interrupting the chain of disease transmission with immunisation and other measures (host–agent–environment model, see Chapter 33).

In the early twentieth century, concerns about the health and poor nutritional status of working class recruits to the British army for the Boer wars led to the development of community nursing services to improve maternal and child health, supported by a growing understanding of the role of vitamins in preventing diseases such as rickets. The rise of the welfare state, providing benefits such as pensions, free school meals and milk, eventually resulted in the provision of universal access to healthcare, free at the point of use. The National Health Service started in 1948, following the creation of the Emergency Medical Service during the Second World War. With the development of antibiotics and other drugs, a new era of effective therapeutics began.

Finally, in the second half of the twentieth century, a rational, evidence-based approach to health and healthcare has emerged. Establishing and assessing evidence of the effectiveness of healthcare and health improvement interventions is now routine (Figure 2c; for explanation of the plot see Chapter 12 on meta-analysis), leading to the development of evidence-based clinical guidelines and services. As the costs of healthcare systems increase, evidence of cost-effectiveness and affordability of interventions is also in demand, leading to the development and application of health economic expertise.

Future public health challenges

If communicable disease, poor living conditions and lack of accessible ...