Disease Control: Levels Of Prevention

Question 1

Disease prevention

Answer 1

A process consisting of specific population and individual based interventions aimed at reducing the burden of disease and associated risk factors.

Question 2

What do the 4 levels of prevention correspond to? List each

Answer 2

They correspond to the different phases of the natural history of a disease.

-Primordial and Primary: Target the seemingly healthy people

• Secondary & Tertiary: Focus on people with or without overt signs of disease.

Question 3

Aim of primordial prevention

Answer 3

To take action to prevent the emergence and establishment of environmental and behavior patterns of living that contribute to elevated risk of disease (alter underlying determinants of disease).

Question 4

What are the Environmental and Behavioral patterns of living that cause a high risk of disease?

Answer 4

Environmental: Social - economic and cultural- physical, biological.

Behavioral patterns - Unhealthy lifestyles, eating habits

Question 5

What does Primordial prevention provide?

Answer 5

An enabling environment through policies and programs to reduce the influence of disease-causing determinants on society.

Question 6

Examples of Primordial prevention at work - nutrition, exercising, substances, sanitation

Answer 6

*Nutrition [standards for import/export of foods,
food processing & labeling, etc.]
*Exercising [promoting environments for walking,
subsidized fitness programs. etc.]
*Tobacco, alcohol and substance use [taxes, labeling, bans, etc.]
*Improving sanitation with laws and measures
reduces or removes the exposure to infections in the first place

Question 7

Aim of Primary Prevention

Answer 7

Reduce the incidence of disease by controlling specific causes and risk factors I.e., alter exposures that lead to disease or enhancing resilience to effects of exposure. (ensure non-exposure to determinants

Question 8

Strategies of primary prevention 1

Answer 8

Population or mass strategy - benefits society as a whole, might not necessarily benefit the immediate individual using the intervention e.g., wearing of seatbelts, vaccination campaigns [cervical cancer, polio, hep B, etc.]

Question 9

Strategies of primary prevention - high risk individual strategy

Answer 9

High risk individual strategy- Focuses on those at high risk of disease e.g., cholesterol reducing agents for those with hypercholesterolemia, smoking cessation for smokers, exercises for the obese, etc.

Question 10

Aim of Secondary Prevention

Answer 10

Reduce consequences of disease through early detection I.e., diagnosis and treatment. [Detect and treat pathological process at an earlier stage when treatment can be more effective.(preclinical and part of clinical phase)

Occurs when treatment is most effective and reduces disease prevalence

Question 11

Prerequisites for secondary prevention

Answer 11

• Safe and accurate method of disease detection at the preclinical stage through screening. E.g. cancer screening programs, diabetes routine FBS for persons
  above 40 years and hypertension screening

*Effective methods of prevention. E.g., preclinical management of cervical cancer, early management of diabetes and hypertension through exercise and nutrition, etc.

Question 12

Aim of Tertiary Prevention

Answer 12

• Reducing the progress or complications of an established disease.

*Important aspect of therapeutic and rehabilitative medicine.

Question 13

What does Tertiary Prevention do?

Answer 13

Reduces suffering and facilitates adjusting of patients to incurable conditions

E.g., managing full fledged HPT, DM, strokes, blindness, injuries, etc.

Targets individuals and families
- coping and adapting mechanisms
* Prevent relapses and further deterioration via follow up care and rehabilitation

Question 14

Screening

Answer 14

The process of using tests on a large scale to identify presence of a disease in apparently healthy people.

Question 15

Types of Screening

Answer 15

Mass- Screening whole population or subset

Multiple/Multiphasic - Using several tests at the same time

Targeted - For groups with specific exposures

Case finding/Opportunistic - Testing for other conditions a person did not report with. E.g., urine test for sugar in a malaria patient.

Question 16

Requirements for instituting a screening program 1

Answer 16

1. The disorder being screened for
   -should be well defined
   -should have an effective remedy
2. The prevalence of the disorder should be known
3. Concerning the natural history of the disorder - there should be a long period between first signs and overt disease
4. The test choice should be simple and safe

Question 17

Requirements for instituting a screening program ii

Answer 17

5. Test performance
   - We should be aware of the test outcomes in persons with or without the disorder I.e., sensitivity and specificity
6. Financial implications of the test
   - Should be cost effective
7. Access to the test
   - Should be available or easily provided

Question 18

Requirements for instituting a screening program iii

Answer 18

8. Acceptability of the test
   - Procedures following a positive result should be agreed upon and acceptable to screeners and those being screened.
9. Equitable access to test and post test management

• Population has equitable access to screening methods
• Effective, acceptable and safe treatment available to population.

Question 19

Characteristics of a Screening Test

Answer 19

1. Test should not be costly
2. Test should be easy to apply
3. Test should be acceptable to the public
4. Results should be reliable - provide consistent results.
5. Test results should be valid - correctly categorizes people into groups with or without the disease i.e. Has good sensitivity and specificity

Question 20

Define Sensitivity and Specificity

Answer 20

*Sensitivity
proportion of people with a disease who are appropriately identified as
ill [positive] by the test relative to a GOLD STANDARD

*Specificity
proportion of disease free people who are appropriately identified as
not having the disease [negative] by the test relative to a GOLD STANDARD

Question 21

Characteristics of A Screening Test II (Predictive values)

Answer 21

6) Positive predictive value of x% implies that
*a person who tests positive in the population under question is x% likely to develop the outcome of interest [disease] in question

7) Negative predictive value of y% implies
that
*a person who tests negative for a screening test in the population in
question is y% likely not to develop the outcome of interest [disease] in question

Question 22

What do predictive values depend on?
What do sensitivity and specificity depend on?

Answer 22

8) Note!!!
* Predictive values depend on the prevalence of a disease condition in the population.
* Sensitivity and specificity depend solely on test outcomes in those studied.