Screening

Question 1

What is lead-time bias?

Answer 1

Artefactual extension of survival through screening

Question 2

What is the programme for screening AAA?

Answer 2

Male aged >65

Ultrasound scan of abdomen

Question 3

What is the programme for screening bowel cancer?

Answer 3

Men and women every 2 years
Age 60-74

FIT test
Bowel Scope test at age 56

Question 4

What is the programme for screening breast cancer?

Answer 4

Women age 50-71 (47-73 in some areas)

Mammogram

Question 5

What is the programme for screening diabetic eye screening?

Answer 5

Annual screening for diabetics >12 years

DES test (30 mins)

Question 6

What is screening?

Answer 6

the systematic application of a test or inquiry, to identify individuals at sufficient risk of a specific disorder to warrant further investigation or direct preventive action, amongst persons who have not sought medical attention on account of symptoms of that disorder

Question 7

Why do we screen?

Answer 7

Opportunities for primary prevention are limited
Opportunities for treatment are limited
Screening gives potential for early and more effective treatment

Question 8

What does the UK National Screening committee believe are the features of a condition required to introduce a screening programme for it?

Answer 8

• Important health problem
• Epidemiology and natural history well understood
• Detectable risk factor
• Latent period
• cost effective primary prevention should have been implemented

Question 9

What does the UK National Screening committee believe are the features of a test that can be introduced to a screening programme?

Answer 9

• Simple, safe, precise and validated
• Distribution of test values and suitable cut-offs agreed upon
• Acceptable
• Agreed policy on further management

Question 10

What does the UK National Screening committee believe are the features of a treatment to introduce a screening programme?

Answer 10

• Effective with early evidence of better outcome
• Agreed policies of who will be offered these treatments
• Clinical management of the condition optimised prior to screening programme

Question 11

What does the UK National Screening committee believe are the features of a programme that can be introduced a screening programme?

Answer 11

• RCT evidence must be available showing that the programme is effecting in reducing mortality or morbidity
• Evidence of acceptable between professionals and public
• Benefits outweigh harms
• Opportunity cost of the programme should economically balance in relation to health care spending
• A plan must be in place for quality assurance and adequate staffing facilities

Question 12

List the current national screening programmes

Answer 12

NHS abdominal aortic aneurysm (AAA) programme
NHS bowel cancer screening (BCSP) programme
NHS breast screening (BSP) programme
NHS cervical screening (CSP) programme
NHS diabetic eye screening (DES) programme
NHS fetal anomaly screening programme (FASP)
NHS infectious diseases in pregnancy screening (IDPS) programme
NHS newborn and infant physical examination (NIPE) screening programme
NHS newborn blood spot (NBS) screening programme
NHS newborn hearing screening programme (NHSP)
NHS sickle cell and thalassaemia (SCT) screening programme

Question 13

How is specificity calculated?

Answer 13

True negative/ All without disease

Question 14

How is sensitivity calculated?

Answer 14

True positive/ All with disease

Question 15

Calculate NPV

Answer 15

True negative/ All negative

Question 16

Calculate PPV

Answer 16

True positive/ All positive

Question 17

How does changing disease influence prevalence of NPV and PPV

Answer 17

As the incidence increase:

The NPV decreases but PPV increases