Screening

Question 1

Define screening

Answer 1

A public health service in which members of a population, who are not necessarily at risk of, or already affected by a disease, are asked a question or offered a test, in order to identify those individuals who are more likely to be helped than harmed by further tests or treatment to reduce the risk of disease.

Question 2

What are the benefits of screening

Answer 2

• detects a disease early so treatment may be more effective
• reduces the risk of developing a condition
• finding out about a disease early allows the patient to make an informed decision

Question 3

What are the limitations of screening

Answer 3

• False positives
• False negatives
• Over-diagnosis & over-treatment
• Resource allocation & opportunity costs
• Exacerbating inequalities

Question 4

List the screening programs available in Scotland

Answer 4

Breast Cancer screening- women aged 50-70
Cervical Cancer (smear test) screening- women aged 25-64
Bowel cancer screening- anyone aged 50-74
Abdominal Aortic Aneurysm (AAA)- men aged 65
Diabetic retinopathy- diabetics aged 12 or over
Pregnancy screening- mums and dads to be
Newborn screening- newborn babies (hypothyroidism, sickle cell)

Question 5

What is the criteria for screening

Answer 5

• condition should be an important problem for the individual and the community
• there should be an accepted treatment for the patients with the disease
• facilities for diagnosis and treatment should be available
• the test should be acceptable by the population
• the test should be a suitable test or examination
• there should be a recognisable latent or early symptomatic stage
• the test should be accessible for the entire target population
• the programme should ensure informed consent, confidentiality and respect for autonomy
• the overall benefits should outweigh the harm

Question 6

Define sensitivity

Answer 6

How good the test is at identifying who DOES has the condition

Question 7

Define specificity

Answer 7

How good the test is at identifying who DOES NOT have the condition

Question 8

Define false positive

Answer 8

How often does the test return a positive result when the disease isn’t present

Question 9

Define false negative

Answer 9

How often does the test return a negative result when the disease is present

Question 10

Define positive predictive value

Answer 10

How likely is a positive result to be true

Question 11

Define negative predictive value

Answer 11

How likely is a negative result to be true

Question 12

What is the calculation for sensitivity

Answer 12

Everyone with condition who tests positive/

Everyone with condition

Question 13

What is the calculation for specificity

Answer 13

Everyone without condition who tests negative/

Everyone without condition