1. Prevention And Screening

2. Prevention Definition
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.

3. Prevention is best defined in the context of levels
Primary (prevent the disease)
Secondary( early detection and treatment
Tertiary prevention (treat and minimize disability)
A fourth level, called primordial prevention(prevent the risk factors) .

4. 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,

5. an organization for applying these measures to appropriate persons or groups, and
continuous evaluation of and development of procedures applied

6. Primordial prevention
Primordial prevention consists of actions and measures - in the form of environmental, economic, social, and behavioral conditions and cultural patterns of living etc.- that inhibit the emergence of risk factors in countries or population groups in which they have not yet appeared
This was part of primary prevention separated later

7. Primordial prevention, a relatively new concept, is receiving special attention in the prevention of chronic diseases. 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.
While Strasser’s idea of primordial prevention was originally concerned with controlling the penetration of risk factors like smoking in developing countries, the concept has important implications regarding the way we think about the relationship between lifecourse socio-economic circumstances and adult risk factors.

8. General access to energy-dense diets coupled with typically sedentary urban lifestyles creates a trend toward obesity and chronic disease.
The term 'epidemiological transition' describes the shift in disease patterns from a dominance of infectious and deficiency diseases to a dominance of chronic diseases (accompanied by a decrease in fertility and population aging), as played out around the world.
Mortality from infectious disease is declining in many developing countries and life expectancy is increasing. Consequently, noncommunicable conditions, especially coronary heart disease, cancer and unintentional injuries, take on a greater relative importance even before the infectious and parasitic diseases have been fully controlled.

9. It is important to change the milieu that promotes major risk factor development. Primordial prevention calls for changing the socio-economic status of society. A better socio-economic status correlates inversely with lifestyle factors like smoking, abnormal food patterns and exercise.
Changes in attitudes, behaviour and social values are important for primordial prevention. They include encouragement of positive health behaviour, prevention of adopting risk behaviour, elimination of established risk behaviour and promotion of the concept of health as a social value.
Established principles and practices of health and general education should be included in public health programmes. Healthy behaviour should be made socially acceptable and encouraged by improved community facilities.

10. Primordial prevention begins in childhood when health risk behaviour begins. Parents, teachers and peer groups are important in impartingنقل health education to children.
The decisive role of health education in schools should be stressed through new social and behavioural values. Close co-operation between the health and teaching profession at all levels is needed. Special target groups are: children and adolescents, the family unit, the under-privileged and other high risk groups. The mass media should play a major role in health education programme.
Promotion of dietary restriction, physically active lifestyle and avoidance of tobacco use beginning from childhood is important for primordial prevention. All adults should know their blood pressure and blood cholesterol levels, should not smoke, should monitor their salt and fat intake and should engage in at least moderate exercise.

11. Examples of primordial prevention actions (I): National policies and programs on nutrition involving the agricultural sector, the food industry, and the food import-export sector السياسات والبرامج الوطنية المتعلقة بالتغذية التي تنطوي على القطاع الزراعي والصناعات الغذائية، وقطاع الاستيراد والتصدير
For nutrition, strategies should include the development of methodologies to encourage healthy eating and policies that support social, economic and marketing environments conducive to healthy eating.

12. Examples of primordial prevention actions (II): Comprehensive policies to discourage smoking سياسات شاملة للحد من التدخين
Activities on smoking prevention should be based on a national plan for tobacco control that includes strategies for data collection, development of health education and information systems and other appropriate policies and legislation.

13. Examples of primordial prevention actions (III): Programs to promote regular physical activity برامج لتعزيز ممارسة النشاط البدني بانتظام
Physical activity programmes should be based on policy, public information, education and training supported by standardized research and evaluation components. All strategies should aim at increasing physical activity in the population as a whole with special emphasis on children and women.

14. Primary prevention
Efforts are directed at healthy individuals to avoid the development of disease .
Primary prevention may be accomplished by measures of “Health promotion” and “specific protection”

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

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

17. 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

18. 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

19. 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.

20. Secondary prevention
Efforts are those aimed at detecting early disease so that further morbidity or symptoms
can be reduced .
The specific interventions are: early diagnosis (e.g. screening tests, and case finding programs….) and adequate treatment.
an example is screening FBS in hypertensive
pt before they developed any symptoms of DM

21. Tertiary prevention Efforts intended to improve both the health
outcomes of people with a diagnosed disease and preventing further morbidity from the condition
Intervention that should be accomplished in the stage of tertiary prevention are disability limitation, and rehabilitation

22. Disability limitation
disease
impairment
disability
handicap

23. Impairment
Impairment is “any loss or abnormality of psychological, physiological or anatomical structure or function.”

24. Disability
Disability is “any restriction or lack of ability to perform an activity in the manner or within the range considered normal for the human being.”

25. Handicap
Handicap is termed as “a disadvantage for a given individual, resulting from an impairment or disability, that limits or prevents the fulfillment تنفيذof a role in the community that is normal (depending on age, sex, and social and cultural factors) for that individual.”

26. Rehabilitation
Rehabilitation is “ 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.”

27. Rehabilitation
Medical
rehabilitation
Vocational
Social
Psychological

28. Tertiary prevention is conducted primarily by individuals and their health care practitioners (physicians, nurses and متحالف allied health professionals). In conducting tertiary prevention, health care professionals may make use of rehabilitation programs, chronic pain management programs and patient support groups

29. . For people with severe arthritis, tertiary prevention often includes doing exercises, physical therapy and taking medication to control inflammation and pain. For people with cancer, tertiary prevention often includes measures to keep the patient comfortable and the disease in remission for as long as possible. For people with disabling injuries, tertiary prevention includes intensive, long-term physical therapy to regain use of limbs or develop alternate means for independent functioning

30. Screening for Disease

31. screening
Screening is testing for a health problem or risk factor when there are no recognized signs or symptoms that would indicate the presence of that problem or risk factor

33. Screening test Reliable – get same result each time
Validity – get the correct result
Sensitive – correctly classify cases
Specificity – correctly classify non-cases

34. Reliability Reliability = Repeatability Get same result : Each time
From each instrument
From each rater

35. TRUE Noncases identified / all noncases
Validity
Sensitivity =Probability (proportion) of correct classification of cases
TRUE Cases / all cases
2. Specificity= Probability (proportion) of correct classification of noncases
TRUE Noncases identified / all noncases

36. The Principles of Screening
The choice of disease for which to screen;
The nature of the screening test or tests to be used;
The availability of a treatment for those found to have the disease;
The relative costs of the screening.

37. The disease must be an important health problem.
There should be a recognizable latent or early symptomatic stage.
The natural history of the disease, including latent to declared disease, should be adequately understood.

38. When to screen?

39. There should be a suitable test or examination.
The test should be acceptable to the population. 

40. Outcomes of a Screening Test
True Disease Status
Screening Test
Positive
Negative
Total
True Positives
(TP)
False Positives
(FP)
TP+FP
False Negatives
(FN)
True Negatives
(TN)
FN+TN
TP+FN
FP+TN
TP+FP+FN+TN

41. There should be an acceptable treatment for the patients with recognized disease.
There should be facilities for diagnosis
and treatment should be available.
There should be an agreed policy on whom to treat as patients.

42. The cost of case finding (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole.
Case finding should be a continuing process and not a "once for all" project.

43. Limitations of screening
The tests used in screening are not perfect.
The test result may incorrectly show positive for those without disease (false positive), or negative for people who have the condition (false negative). Limitations of screening programs can include:

44. Screening can involve cost and use of medical resources on a majority of people who do not need treatment.
Adverse effects of screening procedure (e.g. stress and anxiety, discomfort, radiation exposure, chemical exposure).
Stress and anxiety caused by a false positive screening result.
Unnecessary investigation and treatment of false positive results.
Stress and anxiety caused by prolonging knowledge of an illness without any improvement in outcome.
A false sense of security caused by false negatives, which may delay final diagnosis.

45. Common screening programs
Cancer screening
Pap smear or liquid-based cytology to detect potentially precancerous lesions and prevent cervical cancer
Mammography to detect breast cancer
Colonoscopy to detect colorectal cancer
Faecal occult blood test screening for bowel cancer
PPD test to screen for exposure to tuberculosis
Beck Depression Inventory to screen for depression
Alpha-fetoprotein, blood tests and ultrasound scans for pregnant women to detect fetal abnormalities
Ophthalmoscopy or digital photography and image grading for diabetic retinopathy

46. Summary What is the next step?
Prevention defined as Actions aimed at eradicating, eliminating or minimizing the impact of disease and disability
Screening is the testing of apparently healthy populations to identify previously undiagnosed diseases or people at high risk of developing a disease.
Principles of Screening: disease, test, treatment and cost.
What is the next step?
Define the validity of the screening test and
put screening to use in the population.