L04-Secondary prevention

Question 1

What is Screening?

Answer 1

process of identifying apparently healthy people who may be at increased risk of a disease or condition

Question 2

In terms of screening, what does sensitivity mean?

Answer 2

How good the test is at picking up those with disease

Question 3

How do you calculate sensitivity?

Answer 3

True positives/All those who have the disease

Question 4

In terms of screening, what does specificity mean?

Answer 4

How good the test is at excluding people who don’t have the condition

Question 5

How do you calculate specificity?

Answer 5

True negatives/all of those without disease

Question 6

What is volunteer bias?

Answer 6

• Screened people may differ from non-screened
  o Screened = usually lower risk
• More healthy people tend to attend screening
  o Less likely to die from causes other than breast cancer if they attended screening – healthier lifestyle in general

Question 7

What is lead time bias?

Answer 7

• Time by which diagnosis is advanced because of screening
• Apparent increase in survival
• Not actually getting increased longevity – still same length of time till death, just identified sooner so living longer with the disease

Question 8

What is length bias?

Answer 8

• Those with a long pre-clinical phase more likely to be detected by screening
  o Usually have a better prognosis too (less aggressive disease)

Question 9

What is the difference between a screening test and a screening programme?

Answer 9

Screening tests  sort out apparently well people who probably have a disease from those who probably do not
Screening programmes  systematic invitation of an agreed population of apparently healthy individuals to undertake a screening test (can be at regular intervals)

Question 10

What main factors influence a screening policy?`

Answer 10

Values (result for patient)

Commercial interest