Basic Concepts in Prevention and Health Promotion
After completing this chapter, the reader will be able to:
- Discuss the concept of life course and the natural history of disease, particularly with respect to possible public health and clinical interventions;
- Understand the four levels of prevention (primordial, primary, secondary, and tertiary);
- Appreciate the role that physicians can play in promoting health and preventing diseases at the individual and community level, including health protection and health promotion;
- Describe the five strategies of health promotion as defined in the Ottawa Charter and apply them to relevant situations.
Linking these topics to the Medical Council exam objectives, especially sections 78-3 and 78-4.
Chapters 1 and 2 introduced the NATURAL HISTORY of a disease, from exposure to causal agents through its progression to final outcomes. Understanding the characteristic natural history of a disease enables physicians to anticipate the patient’s prognosis and to identify opportunities for prevention and control.1 For instance, based on his knowledge of Type 2 diabetes, Dr. Rao can be concerned that Catherine Richards may face visual impairment, kidney failure, even possible amputation, if she does not take measures to control her disease. The natural history also suggests the time frame within which he has to intervene to alter the clinical course of her diabetes and prevent the development of more serious consequences.
Ideally, prevention occurs before people contract a disease, so preventive programs are often delivered to currently healthy people in the general population. But at what stage in the natural history should we intervene? The metaphor of the “iceberg of disease” reminds us that for every case that comes to a clinician, there are likely to be many more people with pre-clinical disease in the community, and even more with risk factors for the condition. For some conditions (water-borne parasitic diseases, respiratory disease due to air pollution) virtually everyone in the population is susceptible, so prevention can justifiably target the entire population. For other conditions (e.g. breast cancer) some groups are at higher risk, so prevention can focus on those. Chapter 2 distinguished population health approaches, which target entire populations, from public health programmes which often target identifiable groups. To design such a programme we must, therefore, understand the distribution of the condition in the population and know how to identify future cases.
Figure 4.1 links the phases in the natural history and clinical course of a disease to preventive strategies, or “stages of prevention”. Different groups of experts, in different locations, will deliver the various preventive strategies.
Chapters 1 and 2 illustrated how a patient’s disease follows a natural history that can, for convenience, be broken into a series of stages. Preventive measures can be applied at any stage along the natural history, with the goal of preventing further progression of the condition (see PREVENTION, defined in Glossary). For the purposes of introduction it is convenient to think of preventive actions at four main stages, but in reality the stages blur one into the next.
Primordial prevention consists of actions to modify population health determinants and inhibit the establishment of factors (environmental, economic, social, behavioural) known to increase the future risk of disease.2 It addresses determinants at the systemic level rather than modifying personal risk factors, which is the goal of primary prevention. Thus, outlawing alcohol in certain countries would represent primordial prevention, whereas a campaign against drinking and driving would be an example of primary prevention.
Other examples of primordial prevention include improving sanitation (so that exposure to infectious agents does not occur), establishing healthy communities, promoting a healthy lifestyle in childhood (for example, through prenatal nutrition programs and supporting early childhood development programmes), or developing green energy approaches. Starfield et al. gave more examples.3 So, in preventing Catherine Richards’s diabetes, subsidized fitness programmes at the sports centre should make such activities more affordable for women like her, and could help to make exercise a norm for women in her community. As these are population-level programmes, primordial prevention is conceptually linked to population health and health promotion, but clinicians can play a role in bringing problems to public attention and in advocating for action on determinants.
During the early 1980s the European regional office of the World Health Organization proposed actions to improve the quality of life in cities by making the urban environment conducive to healthy living: providing recreational resources, improved transportation, cleaner environments, more pleasant housing and so on. Toronto was an early participant in the healthy cities movement.4
Primary prevention aims to prevent the onset of specific diseases via risk reduction: by altering behaviours or exposures that can lead to disease, or by enhancing resistance to the effects of exposure to a disease agent. Examples include smoking cessation and vaccination. Primary prevention reduces the incidence of disease by addressing disease risk factors or by enhancing resistance. Some approaches involve active participation, as with regular tooth brushing and flossing to prevent dental caries. Other approaches are passive: adding fluoride to the municipal drinking water to harden tooth enamel and prevent caries. Primary prevention often targets specific agents and the risk factors for specific diseases, but may also aim to promote healthy behaviours, improve host resistance, and foster safe environments that reduce the risk of disease in general, for instance, thorough cleaning of operating rooms to prevent post-operative infection. Primary prevention fits well into the agent-host-environment model of causation introduced in Chapter 2.
Secondary prevention includes procedures to detect and arrest pre-clinical pathological changes and thereby control the progression of a particular disease. Screening procedures (such as mammography to detect early stage breast cancer) are often the first step, leading to early interventions that are more cost effective than intervening once symptoms appear. Routine blood sugar testing for people over 40 would be an example relevant to detecting Catherine’s diabetes early. Screening is usually undertaken by health professionals, either in individual doctor-patient encounters as with routine blood pressure checks, or via public health screening programs (e.g., population mammography screening programmes). The criteria for implementing a screening programme are described in Chapter 9.
Once a disease has developed and has been treated in its acute clinical phase, tertiary prevention seeks to soften the impact of the disease on the patient’s function, longevity, and quality of life. Examples include modifying behavioural risk factors, such as assisting a cardiac patient to lose weight, or making environmental modifications to reduce an asthmatic patient’s exposure to allergens. In the example of Catherine Richards, it might include ensuring regular check-ups to monitor her condition, including eye exams to check for possible adverse outcomes of her diabetes. Where the condition is not reversible, tertiary prevention focuses on rehabilitation, assisting the patient to accommodate to his disability. For reversible conditions, such as many types of heart disease, tertiary prevention will reduce the population prevalence, whereas for incurable conditions it may increase prevalence if it prolongs survival. The key goal for tertiary prevention is to enhance quality of life.
|Colorectal cancer||Individual||Counselling on healthy lifestyles: dietary counselling for people at risk of colorectal cancer, etc.||Hemoccult stool testing to detect colorectal cancer early||Follow-up exams to identify recurrence or metastatic disease: physical examination, liver enzyme tests, chest x-rays, etc.|
|Population||Publicity campaigns alerting the public to the benefits of lifestyle changes in preventing colorectal cancers; promotion of high fibre diets; subsidies to help people access exercise programmes; anti-smoking campaigns||Organized colonoscopy screening programs||Reorganizing health services to improve access to high-quality follow-up care|
|Infectious diseases: hepatitis C||Individual||Counselling on safe drug use to prevent hepatitis C virus (HCV) transmission; counselling on safer sex||Screening for HCV infection of patients with a history of injection drug use||HCV therapy to cure infection and prevent transmission|
|Population||Education on safer sex practices; programmes to discourage needle sharing among intravenous drug users, etc.||Establish a universal testing system for HCV in high risk groups||(Similar to primary prevention); ensuring close control of high risk sites such as tattoo parlours that have been associated with outbreaks|
|Metabolic syndrome||Individual||Nutrition and exercise counselling||Screening for diabetes||Referral to cardiac rehabilitation clinics|
|Population||Build environments conducive to active transport (walking or bicycling rather than using a car)||Community level weight loss and exercise programs to control metabolic syndrome||Implementation of multidisciplinary clinics|
Beware: you may see the term secondary prevention mistakenly used in reference (for example) to preventing a second stroke in a patient who has had a first one. This is incorrect, for this would be an example of tertiary prevention, in terms of preventing further damage to the patient’s vascular system.
Bodies in the river
A passer-by sees a body floating down a river and calls 911. Firemen arrive and haul the person out. Paramedics start resuscitation and rush the victim to the ER; later the hospital public relations office announces that while everything possible was done to save the victim, sadly he died. Suicide is presumed.
The metaphor of “upstream” and “downstream” interventions was introduced in Chapter 2. Applying this to the case of the body in the river, tertiary prevention would include efforts at resuscitation at the scene and in hospital. Obviously these may be judged as “too little, too late.” Secondary prevention activities might focus (metaphorically) further upstream and include attempts to identify suicidal people before they make an attempt, perhaps by screening for depression in primary care practices. Those who give indications of depression could be more fully evaluated, perhaps by referral to a psychologist. The modest success of such counselling, and its limited availability, limit its impact on preventing suicide. Therefore, primary or primordial preventive approaches may be more effective. They represent a transition from identifying individual solutions to group and environmental approaches.
Primary prevention might include social programs for high-risk youth in areas of high suicide rates, or installing safety nets to prevent the act of suicide (which probably only moves the problem elsewhere). Primordial prevention falls in the domain of population health approaches; these involve a wide range of government agencies and focus on developing healthy public policies and altering underlying determinants of health. Applied to the bodies in the river, primordial prevention might include improving youth employment training, attracting small industries to town, or programmes to improve the built environment
More on the stages of prevention
Our presentation of prevention as discrete stages offers a useful introduction to the topic, but classifying a preventive action into a stage depends greatly on the context.
For example, checking and then controlling blood pressure may represent primary prevention if the condition you aim to prevent is a heart attack. But BP control may be seen as secondary prevention if the person has a family history of hypertension and you are screening for this. It may even be tertiary prevention if the patient has already had a heart attack and the goal is to prevent a recurrence. Bother!
Even more confusing: secondary prevention has been defined as slowing the progression of a disease or its sequelae at any point after its inception. From this perspective, treating a disease can be seen as prevention if it slows the progression of the disease or prevents adverse outcomes. From a public health perspective, treating an infectious disease might even qualify as primary prevention because it reduces the risk of transmission of the virus.
Conversely, excess use of antibiotics may be viewed as the opposite of prevention if it contributes to the development of resistant organisms. Clinicians should always weigh the costs and benefits of treating against those of not treating in much the same way as they do in prevention. Reflecting this theme, you may also hear the term ‘quaternary prevention’: where a patient is at risk of over-medication, quaternary prevention protects them from new medical invasion, promoting interventions that are ethically acceptable, and assuring quality of the care process.5
Prevention programmes may be delivered by public health agencies, by individual clinicians (frequently by general practitioners, nurses or nurse practitioners), or by community agencies (including volunteer groups such as students against drunk driving, or non-profit groups). Ideally, programmes should be coordinated between these providers; while we have many good programs in Canada, they tend to be delivered in relative isolation by the single agencies responsible for them, resulting in gaps and overlaps between programs. Programmes also need to be tailored to the local situation: one size does not fit all. This theme is discussed in programme planning in Chapter 12.
HEALTH PROTECTION refers to a wide range of activities undertaken by public health departments and by government agencies such as the Public Health Agency of Canada (PHAC). Health protection spans primordial and primary prevention, and includes “food hygiene, water purification, environmental sanitation, drug safety, and other activities in which the emphasis is on actions that can be taken to eliminate as far as possible the risk of adverse consequences for health attributable to environmental hazards, unsafe or impure food, water, drugs, etc.”6 Public health protection also includes reducing environmental threats such as biological, chemical, or physical agents that could cause an epidemic if not controlled.
Public health agencies are required by law to deal with specified threats that can be detected by SURVEILLANCE systems, as described in Chapter 7. The approach to health protection will vary according to the nature of the biological, chemical, or physical risk involved. For example, federal, provincial and local inspectors work to limit the spread of communicable diseases such as those associated with contamination of water or food. Legislation and regulations address chemical hazards, such as risks due to environmental tobacco smoke, and fines may be applied. Warning signs are often used to make hazards visible and raise public awareness. A traditional public health protection or risk reduction approach to the problem of the bodies in the river might involve adding protective netting to the bridge. Even though nets might not deter a determined suicide attempt, they could reduce impulse suicides and it would help to make the problem visible by reminding passers-by that suicides have occurred in that spot. This recognition may help indirectly, by raising vigilance in the public and encouraging people to take early warning signs seriously.
While health protection focuses on removing negative influences on health, health promotion aims to enhance health in terms of developing healthy public policies, healthy environments and personal resiliency; this reflects a philosophy of supporting communities and individuals to take charge of their own health. Beginning in the 1970s and 1980s, health promotion built on health education (offering pamphlets, posting signs, patient education classes, etc.), which had been criticized as being insufficient (see “Pamphlets may not be enough”, below). The aims of health promotion include, but also go beyond, preventing disease: “Health promotion includes strengthening the skills of individuals to encourage healthy behaviours, and it also includes building the healthy social and physical environments to support these behaviours.”7 It involves “any combination of health education and related organizational, economic, and political interventions designed to facilitate behavioural and environmental changes conducive to health.”8
While a health promotion programme might focus on a specific issue such as smoking cessation, it would typically approach this within a broader set of interrelated interventions including environmental and lifestyle changes that support non-smoking. Enhancing supportive environments and encouraging healthy behaviours contribute to primary prevention of disease, but also have the broader aim of encouraging people to take responsibility for their health. This approach reflects concerns over the erosion of individual responsibility for health that may result from relying on the availability of therapy once disease develops, which was discussed in Chapter 1. Applied to the bodies in the river, a health promotion approach might begin by asking what was causing people to throw themselves into the water, and then attempt to correct this cause. It would typically focus on programs aimed at helping people to cope with stress in their lives, such as arranging mutual-support groups.
Pamphlets may not be enough
Dr. Rao has some pamphlets alerting diabetic patients to the need for careful monitoring and control of their condition in order to avoid serious adverse outcomes but he recognizes that these are not helpful for Catherine, given her increasing memory difficulties. He sees the need for a broader support programme, involving her family members and other community members. He encourages her son Paul and his wife Julie to get Catherine to join a diabetic support group that he is planning to set up. He hopes that they can contribute by leading some physical activities that would get them actively engaged and be good for all of them.
The philosophy of health promotion
Health promotion reflects a characteristic set of liberal values, such as self-responsibility for health, that characterize much of the WHO thinking: “Health promotion is the process of enabling people to increase control over, and to improve, their health.” This definition derived from the WHO conception of health described in Chapter 1: “The extent to which an individual or group is able to realize aspirations and to satisfy needs, and to change or cope with the environment.8” Along with self-responsibility, other core values of health promotion include many ‘upstream’ factors, such as:
- Promoting equity and social justice;
- Applying a holistic definition of health;
- Consideration of the full range of health determinants;
- Addressing environmental influences on health;
- Empowering people and building individual and collective capacity;
- Seeking to enhance people’s social participation; and
- Fostering collaboration between agencies.
Population health promotion starts from a recognition that health behaviours are unlikely to change in a lasting manner unless environmental factors that give rise to them are also changed. This implies mounting a campaign that focuses on community engagement and environmental change in addition to modifying individual behaviours. Just as individuals change what they consider a priority, communities have a more or less well-voiced set of priorities that may support or inhibit efforts to promote health. A survey of perceived community needs is therefore often the first stage in a local health promotion campaign: what does this community perceive as its priorities and how do these match the goals of the health promotion team? A community needs assessment will collect data, typically from surveys and interviews with opinion leaders, on the health and social problems of individuals, families and the community as a whole. Community Health Centres commonly apply a needs-based approach to planning health promotion programmes; these centres typically have community representation on their board of directors and plan programmes based on community input. Engaging community members in the planning process not only ensures that the programme is likely to be relevant to local needs, but also helps to ensure community support for the programme and participation in it. The actual design of the programme may be developed following a case conference of experts in relevant specialties who suggest approaches designed to match the particular local situation.
The principles on which health promotion strategies are designed were described in the Ottawa Charter for Health Promotion.
In 1986, Ottawa was the venue for an international conference sponsored by the WHO to establish the basic design principles for health promotion programmes.8 The resulting charter built on a 1981 Global Strategy to achieve health for all by the year 2000.9 The charter sets out a range of upstream and downstream approaches outlined in the box below.
The Ottawa Charter for Health Promotion
The Ottawa Charter and the Health for All 2000 manifesto included the following strategies:
- Building healthy public policy. The aim is to put health on the agenda for all policymakers, and to ensure that they consider the health implications of their decisions. A healthy public policy is one that avoids the side effect of damaging health while pursuing some other goal.
- Creating supportive environments. The emphasis on environment reflects an awareness of the impact of natural, built, and social environments on health, and proposes a socio-ecological approach to health.
- Strengthening community action. Health promotion requires community empowerment and involvement in setting priorities and in planning and implementing strategies to achieve better health.
- Developing personal skills. Health promotion supports personal and social development through providing information and enhancing life skills.
- Re-orienting health services. Health promotion argues for shifting health resources towards a more equal distribution between treating disease and preventing it. Essentially, health services should be expanded to include the four strategies above in addition to conventional medical care. Responsibility for health promotion services should be shared among individuals, community groups, health professionals, health services, and governments.
The Charter also identified seven prerequisites for health: peace, shelter, education, food, income, a stable eco-system, and sustainable resources. These prerequisites are closely related to the macro-social determinants of health and are essential in understanding why we have failed to reach the goal of ‘health for all by the year 2000’ (HFA 2000) even though it is 15 years past the deadline.10, 11
Discussion points: to what extent has the world failed in this goal, and why? How can a physician influence these factors in his or her practice?
An application of the Ottawa Charter
A public health programme in Glasgow, Scotland, illustrated an application of the Ottawa Charter in an experiment to improve the dental health of 5-year-old children living in deprived neighbourhoods.12 The oral health of Glasgow children had been documented as being among the worst in Western Europe.
A ‘from birth’ caries prevention programme addressed early lifestyle determinants of dental caries, and oral health action teams in each of the city’s 15 health care administrative areas led the interventions.
Here are some examples of the activities they undertook:Building healthy public policy: staff education in all nursery schools; healthy snacks policies introduced in nursery schools; subsidised utensils and food blenders; provided free fluoride toothpaste;
Supportive environments: community oral health promotion events were organized; facilities in nursery schools were improved; they held community consultations; arranged ‘get cooking’ classes;
Developing personal skills: literature was translated into jargon-free language; children were taught tooth brushing skills; dental health song books were developed;
Strengthening community action: there was a strong emphasis on community engagement. This included creating networks of voluntary community activists to give outreach into the communities, leading community groups in identifying ways to promote caries-protective events and behaviours; they trained the trainers.
Reorienting health services: the oral health action teams promoted perinatal oral health sessions in doctors’ offices; created dental registration programmes.
The programme included an evaluative component that will be summarised in Chapter 7.
1. Distinguish between the natural history and the clinical course of a disease.
2. The Pap smear test detects cervical cancer in women at an early stage of the disease when there are no symptoms and the disease is not evident on visual examination. Which of the following statements applies to a woman with no history of cervical cancer who undergoes a Pap smear?
A. She is practicing primordial prevention.
B. She is practicing primary prevention.
C. She is practicing secondary prevention.
D. She is practicing tertiary prevention.
E. This is a screening test, not a preventive procedure.
C) Secondary Prevention
A. Primordial prevention acts early in the causal chain, to alter general social or economic circumstances that give rise to risk factors. The Pap test does not address general circumstances, but a specific disease process.
B. Primary prevention is defined as the avoidance of disease – having a Pap smear would not prevent the disease from occurring.
C. Secondary prevention is defined as the interruption of any disease process before the emergence of recognized symptoms or diagnostic findings of the disorder. The Pap smear test forms an essential step in this process: it identifies the disease process before the emergence of symptoms.
D. Tertiary prevention is defined as the avoidance of negative sequelae of a disease process, once the disease has been diagnosed and treated. The Pap smear concerns early detection; it has nothing to do with subsequent effects of the disease.
E. Yes, it is a screening test, but that forms an integral component of an approach to prevention. So this response is splitting definitional hairs and presumably the physician’s intent in administering the test was to prevent further progression of the cancer.
3. Contrast the underlying philosophies of health promotion and health protection.
Health promotion seeks to foster the capacity for self-responsibility in a community, enabling it to improve its health via collective action. Health protection is set of actions, often supported by legislation, applied by an external authority to avoid adverse health consequences. Involvement of the community may be limited.
4. Summarize the elements in the Ottawa Charter for Health Promotion
Building healthy public policy; Creating supportive environments; Strengthening community action; Developing personal skills, and Re-orienting health services. Now give examples of how these might be put into practice in a typical family medicine centre in the city where you live.
- Bhopal RS. Concepts of epidemiology. Oxford: Oxford University Press; 2002.
- Porta M, editor. A dictionary of epidemiology. New York (NY): Oxford University Press; 2008.
- Starfield B, et al. The concept of prevention: a good idea gone astray? J Epidemiol Community Health. 2008;62:580-3.
- Beaglehole R, Bonita R, Kjellström T. Basic epidemiology. Geneva, Switzerland: WHO; 1993.
- Flynn BC. Healthy cities: toward worldwide health promotion. Annu Rev Public Health. 1996;17:299-309.
- Last JM. A dictionary of public health. New York: Oxford University Press; 2007.
- Green L. National policy on the promotion of health. Int J Health Educ. 1979;22:161-8.
- World Health Organization. Ottawa charter for health promotion. Geneva: WHO; 1986 [cited 2011 June]. Available from: http://www.euro.who.int/en/who-we-are/policy-documents/ottawa-charter-for-health-promotion,-1986.
- World Health Organization. Global strategy for health for all by the year 2000. Geneva: WHO; 1981 [cited 2015 December]. Available from: http://apps.who.int/iris/bitstream/10665/38893/1/9241800038.pdf.
- Bryant JH, Zuberi RW, Thaver IH. Alma Ata and health for all by the year 2000. The roles of academic institutions. Infec Dis Clin North Am. 1991;5(2):403-16.
- Gunning-Schepers LJ. “Health for all by the year 2000”: a mere slogan or a workable formula? Health Policy. 1986;6(3):227-37.
- Blair Y, Macpherson L, McCall D, McMahon A. Dental health of 5-year olds following community-based oral health promotion in Glasgow, UK. Int J Paediatric Dentistry. 2006;16:388-98.