Prevention & Screening

Question 1

Is the proportion of people with a long term/chronic condition expected to increase, decrease or stay the same in future?

Answer 1

Increase

Question 2

What are 3 reasons given by the NHS long term plan (in the prevention section)for the increased demand on NHS?

Answer 2

• Growing population
• Growing visibility & concern about unmet health needs
• Expanding frontiers of medical science and innovation (new treatments which the modern health service should be rightly providing)

Question 3

What do studies show about the relationship between perfect care and death?

Answer 3

Perfect care can prevent disease and postpone disease. B

Question 4

What is benefit-cost ratio and how do you calculate it?

Answer 4

Ratio of benefit to cost

CBR= benefit/cost

Question 5

What is ROI and how do you calculate it?

Answer 5

Return on investment

ROI= (benefit-cost)/ cost
… which can also be wrote as CBR-1

Question 6

State the 4 levels of prevention

Answer 6

• Primordial
• Primary
• Secondary
• Tertiary

Question 7

Describe primordial prevention include:

• description
• goal
• strategies
• target population

Answer 7

• Avoiding the emergence and establish,ent of cultural patterns of living that are known to contribute to an elevated level of disease (eliminate risk factors)
• Health promotion/improvement
• General population

Question 8

Describe primary prevention include:

• description/goal
• strategies
• target population

Answer 8

• Preventing the onset of pathological changes
• Interventions applied before there is any pathology e.g. vaccination, smoking cessation, water fluoridation
• Susceptible population

Question 9

Describe secondary prevention include:

• description
• goal
• strategies
• target population

Answer 9

• Concerned with detecting a disease at its earliest stages before symptoms appear and intervening to slow or stop its progression
• E.g. screening
• Asymptomatic population

Question 10

Describe tertiary prevention include:

• description/ goal
• strategies
• target population

Answer 10

• Concerned with arresting the progress of an established disease and to control its negative consequences
• E.g. treatment/ rehabilitation. So reducing disability and handicap, promoting adjustment
• Symptomatic patients

Question 11

Discuss some of WHO criteria for a screening programme

Answer 11

Question 12

Define impairment

Answer 12

Any loss or abnormality of psychological, physiological or anatomical structure or function

Question 13

Define disability

Answer 13

Any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being

Question 14

Define handicap

Answer 14

A disadvantage for a given individual that limits or prevents the fulfilment of a role that is normal for that individual

Question 15

Define screening

Answer 15

The presumptive identification of unrecognised disease or defect by the application of tests, examinations or other procedures that can be applied rapidly to sort out apparently well persons who probably have a disease from those who probably do not.

Question 16

All screening tests require confirmation by diagnostic test or procedure. State what test results are confirmed and why.

Answer 16

High risk = confirmed
Low risk= not confirmed (assumed to be correct until proven otherwise)

Due to cost effectiveness

Question 17

Describe difference between clinical care and screening.

Answer 17

Clinical care= person presents go health care professional for help with symptoms or concerns

Screening- health care professional presented to person and offers help where there are no symptoms or concerns

Question 18

Is there greater responsibility for care in screening or in clinical care?

Answer 18

Screening

Question 19

Define positive predictive value

Answer 19

The proportion of positive tests who are cases.
(=cases/total high risk)

The proportion of people with high risk results that are subsequently confirmed as having the disease or defect

Question 20

Define negative predictive value

Answer 20

The proportion of negative tests who are not cases.
(=non-cases/total low risk)

The proportion of people with low risk results that are subsequently confirmed as not having the disease or defect

Question 21

Define sensitivity

Answer 21

Proportion of cases which the test correctly detects (all those with disease)

Calculation: number of high risk with disease/ total high risk

Question 22

Define specificity

Answer 22

Proportion of non-cases which the test correctly detects (all those without disease)

Calculation: number of high risk with no disease/total high risk w

Question 23

What would be the effect of an increase in prevalence of disease on the positive predictive value and negative predictive value.

Answer 23

• PPV: increase (more common, more likely a high risk to be confirmed as correct)
• NPV: decrease

Question 24

What would be the effect of a decrease in prevalence of a disease on the positive predictive value and negative predictive value.

Answer 24

• PPV: decrease

- NPV: increase (less common, more likely a low risk result with be confirmed as correct)

Question 25

If you lower cut-off threshold for screening test to be high risk what happens to sensitivity and specificity?

Answer 25

Sensitivity increases

Specificity decreases

Question 26

If you increase cut-off threshold for screening test result to be high risk what happens to sensitivity and specificity?

Answer 26

Sensitivity decreases

Specificity increases

Question 27

What is likelihood ratio?

Answer 27

Optimum threshold for screening test to be high risk. It compares how much more likely a case is to have a particular result than a non case.

Question 28

How do you calculate positive likelihood ratio for high risk results?

Answer 28

Sensitivity/(1-specificity)

Question 29

How do you calculate negative likelihood ratio for low risk results?

Answer 29

(1-sensitivity)/specificity

Question 30

What is a receiver operating characteristic curve (ROC curve)?
What shape indicates excellent results?

Answer 30

True positive rate (sensitivity) against false positive rate (1-specificity).

Steepest rectangular hyperbola is the best.

Question 31

There are four main criteria for selection of a screening programme; state them.

Answer 31

• Features of a disease (e.g. known aetiology and risk factors, common or serious)
• Features of test (e.g. simple, acceptable, valid, reliable)
• Features of treatment (e.g. available, acceptable, effective, benefits from early detection)
• Features of programme (e.g. cost effective, agreed protocol, does more good than harm)