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Question 1

Why is good evidence vital?

Answer 1

• Ineffective treatments are used
• Give treatments for which harms outweigh the benefits
• Fail to provide effective interventions
• New expensive treatments may be no better then older
  cheaper ones

Question 2

Why is it difficult to communicate all the evidence

Answer 2

• Adverts backed up by dubious scientific claims
• Endorsements by prominent people
• Scares and conspiracy theories
• The value that people place on individual stories may lead
  people to ignore objective evidence

Question 3

Primary level of prevention

Answer 3

interventions that attempt to prevent disease from occurring - reduce the incidence of disease

Question 4

Secondary levels of prevention

Answer 4

redcue impact of disease by shortening its duration, reducing severity or preventing reoccurrence

Question 5

Tertiary levels of prevention

Answer 5

reduce the number or impact of complications: improve rehabilitation

Question 6

Population/ mass approaches

Answer 6

aims to reduce the health risks of the entire population

Question 7

High risk strategy

Answer 7

individuals in special need are identified

the preventive process then takes the form of controlling the level of exposure to a cause or providing protection against the consequences of the exposure in the high risk group

Question 8

Advantages and disadvantages of population/ mass strategy

Answer 8

Advenantges
- radical
- Behavouly appropriate
- Large potential for whole population

Disadvantages
- small benefit to individuals
- Poor motivation of individuals
- Benefit-to-risk ratio may be low for individuals

Question 9

High risk / individual strategy advances and disadvantages

Answer 9

Advantages
- appropriate to individuals
- Individual motivation
- Clinical motivation
- Favourable benefit-risk ratio for individuals

Disadvantages
- need to identify individuals
- Might be against population norms
- Can be hard to sustain behavioural change

Question 10

PREVENTION PARADOX:

Answer 10

a large number of people at small risk may give rise to more cases of disease then the small number who are at high risk
a preventive measure that brings large benefit to the community may offer little to each participating individual

Question 11

What is screening

Answer 11

The widespread use of a simple test for a disease in an apparently health population

Question 12

What is a screening programme

Answer 12

An organised system using a screening test among asymptomatic people in the population to identify early cases of disease in order to improve outcomes

Question 13

Screening test

Answer 13

A test, usually relatively cheap and simple, used to test large numbers of apparently health people to identify individuals suspected of having easily disease who will then go on to have further diagnosis tests to confirm the diagnosis.
A screening test differs from a diagnostic test in that there is greater emphasis on cost and safety… and less on definitive diagnosis.

Question 14

A screening test is not a diagnostic test, a screening test is not a screening programme

Question 15

Screening is a pathway not a test

Question 16

Screeening programmes are different from base finding or opportunistic screening

Question 17

Because screening is resource intensive we usually do it when

Answer 17

High prevalence of pre-clinical disease

UNLESS:
- serious disease
- cheap and easy to administer

Question 18

ong lead time = greater chance of detecting disease early

Question 19

Critical points

Answer 19

1. Disease is not detectable
2. Usually diagnosed anyway – no benefit
3. Screening may be of benefit

Answer 20

Over treatment
Over diagnosis
Over treatment

Question 21

PVs are influenced by…

Answer 21

Disease prevalence in the population of interest, unlike sensitivity and specificity

Question 22

Is the programme effective?

Answer 22

Evidence from Randomized Controlled Trials of benefit (reduced mortality and/or morbidity) prior to initiation
Ongoing evaluation of programmes once implemented

Crucial to determine if screening programme actually leads to benefit

Question 23

Benefits of screening programmes

Answer 23

Potential for early detection and intervention – reduced mortality and/or morbidity
– possibly less radical treatment required
• Reassurance (true negatives)
• Improved health of population

Question 24

Harms of screening programmes

Answer 24

1. Increase health inequities
2. Physical
3. Physiological
4. Financial

Question 25

Over-diagnosis and/or over-treatment- may…..

Answer 25

Increase morbidity without reducing mortality

• False positives- period of stress and uncertainty until diagnostic test
  • May diagnose a disease that would never have become apparent

LEAD TIME BIAS

Question 26

L ength bias

Answer 26

Screening is biased towards detecting slowly- developing disease that may never have required treatment ( therefore better prognosis)

Question 27

Length bias

Answer 27

Screening is biased towards detecting slowly- developing disease that may never have required treatment ( therefore better prognosis)

Question 28

When to screen: disease

Answer 28

• Seriousness of disease
  • Prevalence of pre-clinical disease
  • Lead time
  • Ability to alter the course of disease – point where prognosis can be improved
  – effective treatment available?

Question 29

Is the test accurate?

Answer 29

Sensitivity, specificity, PPV, NPV