Concepts of Disease Prevention

1. Concepts of Disease Prevention Dr. Adeel Ahmed Khan MBBS, FCPS (Community Medicine)

2. Overview • What is Prevention • Levels of Prevention • Modes of Intervention

3. Public Health Approach Public Health Model • Medical • Model Versus

4. What is Prevention? • The goals of holistic care is: • to promote health, • to preserve health, • to restore health when it is impaired, • to minimize suffering and distress. These goals are embodied in the word "prevention"

5. Prevention; Definition and Concept • Actions aimed at eradicating, eliminating or minimizing the impact of disease and disability, or if none of these are feasible, retarding the progress of the disease and disability. • The concept of prevention is best defined in the context of levels, traditionally called primary, secondary and tertiary prevention. A fourth level, called primordial prevention, was later added.

6. Levels of Prevention; Concept

7. Determinants of 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

8. Preventable Causes of Disease BEINGS • Biological factors and Behavioral Factors • Environmental factors • Immunologic factors • Nutritional factors • Genetic factors • Services, Social factors, and Spiritual factors [JF Jekel, Epidemiology, Biostatistics, and Preventive Medicine, 1996]

9. Stage of disease Level of prevention Type of response Pre-disease Primary Prevention Health promotion and Specific protection Pre-symptomatic Diagnosis and treatment Secondary prevention Latent Disease Symptomatic Disease Tertiary prevention • Disability limitation for • early symptomatic disease • Rehabilitation for late • Symptomatic disease Leavell & Clark’s Levels of Prevention

10. Levels of prevention

11. Levels of prevention Primordial prevention Focus on Healthy People Primary prevention Secondary prevention Focus on Sick People Tertiary prevention

12. Primordial Prevention • Primordial prevention consists of actions and measures that inhibit the emergence of risk factors in the form of environmental, economic, social, and behavioral conditions and cultural patterns of living etc.

13. Primordial prevention (cont.) • It is the 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 (e.g., obesity, hypertension) have their early origins in childhood, because this is the time when lifestyles are formed (for example, smoking, eating patterns, physical exercise).

14. Primordial prevention (cont.) • 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

15. Primary prevention • Primary prevention can be defined as the action taken prior to the onset of disease, which removes the possibility that the disease will ever occur. • It signifies intervention in the pre-pathogenesis phase of a disease or health problem. • Primary prevention may be accomplished by measures of “Health promotion” and “Specific protection

16. Primary prevention (cont.) • 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". • 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.

17. Primary prevention Achieved by Health promotion Specific protection Immunization Health education Chemoprophylaxis Environmental modifications Use of specific nutrients or supplementations Protection against occupational hazards Nutritional interventions Safety of drugs and foods Control of environmental hazards, e.g. air pollution Life style and behavioral changes Primary Prevention

18. Health promotion • Health promotion is “ the process of enabling people to increase control over the determinants of health and thereby improve their health”.

19. Approaches for Primary Prevention • The WHO has recommended the following approaches for the primary prevention of chronic diseases where the risk factors are established: • a. Population (mass) strategy • b. High -risk strategy

20. Population (mass) strategy • “Population strategy" 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

21. 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.

22. Seat Belts

23. Smoking

24. Environment

25. Handicap facilities

27. Secondary prevention • It is defined as “ action which halts the progress of a disease at its incipient stage and prevents complications.” • The specific interventions are: early diagnosis(e.g. screening tests, and case finding programs….) and adequate & prompt treatment.

28. Secondary prevention (cont.) • Secondary prevention attempts to arrest the disease process, restore health by seeking out unrecognized disease and treating it before irreversible pathological changes take place, and reverse communicability of infectious diseases. • It thus protect others in the community from acquiring the infection and thus provide at once secondary prevention for the infected ones and primary prevention for their potential contacts.

29. Early diagnosis and treatment • WHO Expert Committee in 1973 defined early detection of health disorders as “ the detection of disturbances of homoeostatic and compensatory mechanism while biochemical, morphological and functional changes are still reversible.” • The earlier the disease is diagnosed and treated, the better it is for prognosis of the case and in the prevention of the occurrence of other secondary cases.

31. Tertiary prevention • It is used when the disease process has advanced beyond its early stages. • It is defined as “all the measures available to reduce or limit impairments and disabilities, and to promote the patients’ adjustment to irremediable conditions.” • Intervention that should be accomplished in the stage of tertiary prevention are disability limitation, and rehabilitation.

33. MODES OF INTERVENTION Intervention: • An attempt to intervene or interrupt the usual sequence in the development of disease in man. This may be by the provision of treatment, education, help or social support.

34. MODES OF INTERVENTION 5 methods of intervention: • Health promotion • Specific protection • Early diagnosis and prompt treatment • Disability limitation • Rehabilitation Primary prevention Secondary prevention Tertiary prevention

35. MODES OF INTERVENTION 5 methods of intervention: • Health promotion • Specific protection • Early diagnosis and prompt treatment • Disability limitation • Rehabilitation Primary prevention Secondary prevention Tertiary prevention

36. Health promotion Definition: “The process of enabling people to increase control over the determinants of health and thereby improve their health”. • It is not directed against any particular disease, but is intended to strengthen the host through a variety of approaches (intervention). Contd…

37. Health promotion • Health education • Good nutrition • Personality development / lifestyle • Provision of adequate housing • Provision of good working conditions • Adequate recreation facilities • Marriage counseling & sex education • Genetic counseling • Periodic health examinations

38. Health promotion Interventions include: Health education It is cost effective approach Many diseases can be prevented with little or no medical intervention if people are informed and encouraged to take necessary precautions against these diseases.

39. Health promotion Environmental changes/modification • Provision of safe water supply • Sanitary latrines installation • Insect and rodent control • Improvement of housing Contd…

40. Health promotion Nutritional interventions • Food distribution and nutritional improvement of vulnerable groups • Proper weaning practices / child feeding program • Food fortification • Nutrition education – balanced diet

41. Health promotion Life Style and behavioral changes Health education is the basic element of all health activity. It is of paramount importance in changing the views, behavior and habits of people. • Encouraging physical activity, hygiene and healthy life styles • Discouraging smoking, physical inactivity, addiction • Modifying diet patterns

42. Specific protection Idea is to avoid disease altogether. Interventions includes: • Immunization [(active immunization against polio, measles, Hep B etc.) (passive immunity for tetanus, rabies etc.)] • Use of specific nutrients (e.g. against PEM) • Chemoprophylaxis (e.g. chloroquine against malaria) • Protection against occupational hazards (use of safety goggles, helmets etc.) • Protection against accidents …

43. Specific protection vi. Protection from carcinogens vii. Avoidance of allergens viii. Better environmental conditions e.g. control of air and noise pollution ix. Control of consumer product quality and safety of foods, drugs, cosmetics

44. MODES OF INTERVENTION 5 methods of intervention: • Health promotion • Specific protection • Early diagnosis and prompt treatment • Disability limitation • Rehabilitation Primary prevention Secondary prevention Tertiary prevention

45. Early diagnosis and prompt treatment Interventions: • Early diagnosis: better prognosis, better prevention of further occurrence of a disease / long term disability. Screening (Breast cancer, essential HTN, vision) Contact Tracing (T.B, STDs, Leprosy) Individual exam (History, GPE, lab investigation) • Prompt treatment Individual Treatment e.g. anti HTN, anti diabetics Mass Treatment e.g. malaria, trachoma

46. Prevention Paradox • A preventive measure which brings much benefit to the population often offers little to each participating individual. • Classical example is the Framingham study: • Data from the study suggests that if all men upto age 55 reduced their cholesterol level by 10%, 1 in 50 could expect to avoid a heart attack on average, yet 49 out of 50 would follow same measures and perhaps get nothing out of it.

47. MODES OF INTERVENTION 5 methods of intervention: • Health promotion • Specific protection • Early diagnosis and prompt treatment • Disability limitation • Rehabilitation Primary prevention Secondary prevention Tertiary prevention

48. DISABILITY LIMITATION Objective: • Arrest the disease process & prevent its further complications • Provision of facilities to limit disability • To halt the transition of the disease process from impairment to handicap.

49. Disease Impairment Disability Handicap Disability limitation

50. Impairment • Impairment is “any loss or abnormality of psychological, physiological or anatomical structure or function.” • e.g. Loss of foot, defective vision or Mental retardation May be: • Visible or invisible, • Temporary or permanent, • Progressive or regressive