Levels of Prevention - Park's Textbook of Preventive and Social Medicine

Overview

1. Primordial Prevention
2. Primary Prevention
3. Secondary Prevention
4. Tertiary Prevention

Note: Authorities on preventive medicine do not agree on the precise boundaries between these levels, but that does not minimize their importance. These differences of opinion are "more semantic than substantive."

1. Primordial Prevention

• This is a newer concept, receiving special attention in the prevention of chronic diseases
• It is "primary prevention in its purest sense"
• Many adult health problems (obesity, hypertension) have their early origins in childhood, when lifestyles are formed (e.g., smoking, eating patterns, physical activity)
• In primordial prevention, efforts are directed at discouraging children from adopting harmful lifestyles
• Main intervention: Individual and mass education

2. Primary Prevention

• Intervenes in the pre-pathogenesis phase
• Goes beyond averting disease - it includes the concept of "positive health": enabling every individual to lead a socially and economically productive life

Two WHO-recommended approaches for chronic diseases:

• Directed at the whole population, irrespective of individual risk levels
• Even a small reduction in average blood pressure or serum cholesterol can produce a large reduction in cardiovascular disease incidence
• Directed toward socio-economic, behavioural, and lifestyle changes

• Aims to bring preventive care to individuals at special risk
• Requires detection of high-risk individuals by optimum use of clinical methods

Measures include:

• Health promotion (positive health)
• Specific protection (immunization, environmental sanitation, food/water safety, occupational hazard protection, etc.)

All three approaches - primordial, population strategy, and high-risk strategy - should be implemented as they are complementary to each other.

3. Secondary Prevention

Specific interventions:

1. Early diagnosis - screening tests, case-finding programmes
2. Adequate treatment

Objectives of secondary prevention:

• Arrest the disease process
• Restore health by seeking out and treating unrecognized disease before irreversible pathological changes occur
• Reverse communicability of infectious diseases
• Protect contacts in the community (simultaneously providing primary prevention for them)

Limitations:

• Largely the domain of clinical medicine
• The patient has already suffered mental anguish, physical pain, and loss of productivity
• More expensive and less effective than primary prevention in the long run
• An "imperfect tool" in the control of disease transmission

4. Tertiary Prevention

• Intervenes in the late pathogenesis phase
• Treatment, even if undertaken late, may prevent sequelae and limit disability
• When defect and disability are stabilized, rehabilitation plays a key preventive role
• Modern rehabilitation includes psychosocial, vocational, and medical components based on teamwork from a variety of professions
• Extends the concept of prevention into the fields of rehabilitation

Summary Table (Table 10 from Park)

Modes of Intervention (Related Concept)

1. Health promotion - Raises general health standards; not directed at any specific disease
2. Specific protection - Immunization, use of specific nutrients, protection from carcinogens
3. Early diagnosis and treatment - Case finding, screening
4. Disability limitation - Adequate treatment to prevent further complications
5. Rehabilitation - Reducing functional impairment from established disease

Tertiary Prevention - Park's Textbook of Preventive and Social Medicine

Definition

"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." (Leavell & Clark, cited in Park)

• Intervenes in the late pathogenesis phase of disease
• Comes into play when the disease process has advanced beyond its early stages
• Treatment, even if undertaken late in the natural history of disease, may still prevent sequelae and limit disability
• Extends the concept of prevention into the field of rehabilitation

Position in Table 10 (Levels of Prevention)

Two Modes of Intervention at the Tertiary Level

Mode 4: Disability Limitation

The Concept of Disability (WHO Classification)

Disease → Impairment → Disability → Handicap

• Defined as "any loss or abnormality of psychological, physiological or anatomical structure or function"
• Examples: loss of foot, defective vision, mental retardation
• May be visible/invisible, temporary/permanent, progressive/regressive
• One impairment can lead to secondary impairments (e.g., in leprosy: nerve damage [primary] → plantar ulcers [secondary])

• Defined as "any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being"
• Arises because of an impairment

• Defined as "a disadvantage for a given individual, resulting from an impairment or a disability, that limits or prevents the fulfilment of a role that is normal (depending on age, sex, and social and cultural factors) for that individual"
• The person experiences disadvantages and cannot discharge obligations expected of them in society

Example (Accidents):

Key point: The intervention in disability is often social or environmental as well as medical. While impairment (earliest stage) has a large medical component, disability and handicap (later stages) have larger social and environmental components.

Mode 5: Rehabilitation

"The combined and coordinated use of medical, social, educational and vocational measures for training and retraining the individual to the highest possible level of functional ability." (WHO)

• Includes all measures aimed at reducing the impact of disabling and handicapping conditions
• Aims to enable the disabled/handicapped to achieve social integration
• Social integration = active participation of disabled and handicapped people in the mainstream of community life

Components of Rehabilitation (Four Areas):

Rehabilitation Medicine (Physiatry)

• Has emerged as a distinct medical specialty - also called Physical Medicine or Physiatry
• Aims to enhance and restore functional ability and quality of life for those with physical impairments
• A physiatrist specializes in restoring optimal function to people with injuries to muscles, bones, ligaments, or the nervous system

1. Neuromuscular medicine
2. Pain medicine
3. Paediatric rehabilitation medicine
4. Spinal cord injury medicine
5. Sports medicine
6. Brain medicine (neurorehabilitation)

• Physiotherapy / Physical medicine
• Occupational therapy
• Speech therapy
• Audiology
• Psychology
• Education
• Social work
• Vocational guidance and placement services

Examples of Rehabilitation:

• Establishing schools for the blind
• Provision of aids for the crippled
• Reconstructive surgery in leprosy
• Muscle re-education and graded exercises in neurological disorders
• Change of profession to a more suitable one
• Modification of life in tuberculosis and cardiac patients

Purpose of rehabilitation: "To make productive people out of non-productive people."

Key Philosophical Point:

"The responsibility of the doctor does not end when the temperature touches normal and stitches are removed." The patient must be restored and retrained "to live and work within the limits of his disability but to the hilt of his capacity."

Important Limitations of Tertiary Prevention

• Rehabilitation is a "difficult and demanding task that seldom gives totally satisfactory results"
• Requires enthusiastic cooperation from different segments of society as well as expertise, equipment, and funds
• These resources are often not readily available even in affluent societies
• Interventions at earlier stages (primary/secondary prevention) are more feasible, will yield better results, and are less demanding of scarce resources

Disease-Specific Example: Tertiary Prevention in Diabetes Mellitus

• Blindness
• Kidney failure
• Coronary thrombosis
• Gangrene of the lower extremities

• Organize specialized Diabetic Clinics providing diagnostic and management skills of a high order
• Establish such clinics in large towns and cities
• Involve tertiary level in basic, clinical, and epidemiological research
• Establish local and national registries for diabetics