The goals of medicine are to promote health, to preserve health, to restore health when it is impaired, and to minimize suffering and distress. These goals are embodied in the word “prevention”. Successful prevention depends upon a knowledge of causation, dynamics of transmission, identification of risk factors and risk groups, availability of prophylactic or early detection and treatment measures, an organization for applying these measures to appropriate persons or groups, and continuous evaluation of and development of procedures applied. Hence the concept of prevention takes birth.
It is not necessary (although desirable) to know everything about the natural history of the disease to initiate preventive measures. Often times, removal or elimination of single known essential cause may be sufficient to prevent a disease. The objective of preventive medicine is to intercept or oppose the “cause” and thereby the disease process. This epidemiological concept permits the inclusion of treatment as one of the modes of intervention.
Levels of prevention
In modern-day, the concept of prevention has become broad-based. It has become customary to define prevention in terms of four levels:
- Primordial prevention
- Primary prevention
- Secondary prevention
- Tertiary prevention
Primordial prevention, a new concept, is receiving special attention in the prevention of chronic diseases. This is primary prevention in its purest sense, that is, prevention of the emergence or development of risk factors in countries or population groups in which they have not yet appeared. For example, many adult health problems have their early origins in childhood, because this is the time when lifestyles are formed. In primordial prevention, efforts are directed towards discouraging children from adopting harmful lifestyles. The main intervention in primordial prevention is through individual and mass education.
Primary prevention can be defined as “action taken prior to the onset of disease, which removes the possibility that a disease will ever occur”. It signifies intervention in the pre-pathogenesis phase of a disease or health problem or other departure from health. Primary prevention may be accomplished by measures designed to promote general health and well-being, and quality of life of people or by specific protective measures.
Primary prevention is far more than averting the occurrence of disease and prolonging life. It includes the concept of “positive health”, a concept that encourages achievement and maintenance of “an acceptable level of health that will enable every individual to lead a socially and economically productive life”. It concerns an individual’s attitude towards life and health and the initiative he takes about positive and responsible measures for himself, his family and his community.
The concept of primary prevention is now being applied to the prevention of chronic diseases such as coronary heart disease, hypertension and cancer based on elimination or modification of “risk factors” of disease. The WHO has recommended the following approaches for the primary prevention of chronic diseases where the risk factors are established: i) Population strategy and ii) High-risk strategy
- Population strategy: It is directed at the whole, population irrespective of individual risk levels. For example, studies have shown that even a small reduction in the average blood pressure or serum cholesterol of a population would produce a large reduction in the incidence of cardiovascular disease. The population approach is directed towards socio-economic, behavioral and lifestyle changes.
- High-risk strategy: The high risk strategy aims to bring preventive care to individuals at special risk. This requires detection of individuals at high risk by the optimum use of clinical methods.
Primary prevention has proved to be good at eliminating a number of communicable diseases from industrialized countries. Some of the examples of elilminated diseases are cholera, typhoid and dysentery. They are able to control many diseases like plague, leprosy, and tuberculosis. All these eliminating and controlling has happened not by medical interventions but by raising the standard of living that is primary prevention.
In summary, primary prevention is a holistic approach. It relies on measures designed to promote health or to protect against specific disease “agents” and hazards in the environment. Fundamental public health measures and activities such as sanitation; infection control; immunization; protection of food, milk and water supplies; environmental protection; and protection against occupational hazards and accidents are all basic to primary prevention.
Secondary prevention can be defined as “action which halts the progress of disease at its incipient stage and prevents complaints”. The specific interventions are early diagnosis (e.g., screening tests, case finding programs) and adequate treatment. By early diagnosis and adequate and treatment, secondary prevention attempts to arrest the disease process: restore health by seeking out unrecognized disease and treating it before irreversible pathological changes have taken place, and reverse communicability of infectious diseases. It may also protect others in the community from acquiring the infection and thus provide, at once, secondary prevention for the infected individuals and primary prevention for their potential contacts.
Secondary prevention is largely the domain of clinical medicine The health programs initiated by governments are usually at the level of secondary prevention.
Secondary prevention is an imperfect tool in the control of transmission of disease. It is often more expensive and less effective than primary prevention. In the long run, human health, happiness, and useful longevity will be achieved at far less expense with less suffering through primary prevention than through secondary prevention.
When the disease process has advanced beyond its early stages, it is still possible to accomplish prevention by what might be called “tertiary prevention”. It signifies intervention in the late pathogenesis phase. Tertiary prevention can be defined as “all measures available to reduce or limit impairments and disabilities, minimize suffering caused by existing departures from good health and to promote the patient’s adjustment to irremediable conditions”. For example, treatment even if undertaken late in the natural history of the disease may prevent sequelae and limit disability. When defect and disability are more or less stabilized, rehabilitation may play a preventable role. Modern rehabilitation includes psychosocial, vocational, and medical components based on teamwork from a variety of professions.
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