SPR L9 Population Screening

Question 1

Population Screening

Learning Outcomes

Answer 1

LO1 - Understand the theory behind any population screening programme.

LO2 - Understand how the performance of screening tests is assessed.

LO3 - Be able to outline the principles of screening programme evaluation

LO4 - Know of the major types of population screening programme in the NHS and who is responsible for commissioning them

• Special requirements of genetic screening programmes
• The organisation of and anticipated benefit from CRC and AAA screening and the trade-offs.

Question 2

LO1 - Understand the theory behind any population screening programme.

Prevention

Outline the following levels of prevention

1. Primary
2. Secondary
3. Tertiary

Answer 2

1. Education, immunisation, environmental measures, social policy.
2. Pre-symptomatic screening - Early diagnosis with prompt and effective treatment.
3. Rehabilitation.

Question 3

LO1 - Understand the theory behind any population screening programme.

Screening

1. What is Screening?
2. What is the rationale behind screening?
   
   1. Outline Type A and give an example?
   2. Outline Type B and give an example?

Answer 3

1. Scrutiny of people in order to detect the presence of disease, disability or other attributable under study.
2. Early diagnosis leads to more effective treatment & greater cure rate.
   
   1. Screening to detect early stage or asymptomatic disease – e.g. Mammogram
   2. Screening detects a precancerous state e.g. cervical cancer.

Question 4

LO1 - Understand the theory behind any population screening programme.

Screening for disease

What is screened for in the following groups?

1. In Utero
2. Birth
3. Children
4. Pregnant Women
5. Adults
6. Genetic Predisposant

Answer 4

1. Downs, NTDs.
2. PKU, Dislocation hip. Hypothyroidism
3. Sight, hearing
4. Anaemia, BP
5. Hypertension
6. FH, BRCA1/2, Huntingtons

Question 5

LO1 - Understand the theory behind any population screening programme.

Requirements of a screening programme (Wilson Jungner criteria)

What are these criteria?

1. What is Lead Time Bias?
2. What is Length Bias?
3. What are interval cancers?

Answer 5

• Disease important health problem.
• Recognisable latent/early symptomatic stage.
• Facilities for diagnosis and treatment.
• Cost considered in context other demand for resources - opportunity costs.
• Agreed policy on whom to treat as patients
• Does treatment confer benefit?

1. Screening detects the disease earlier but there is no difference to outcome.
2. The screening test increases detection of low risk tumours which may never cause symptoms, be detected otherwise, or cause harm to health.
3. cases which present symptomatically who were screened negative, before their next screening appointment is due. Overrepresatation in the slower growing tumours (there for longer in the screenshot)

True Interval - appear ‘de novo’. False Negatives Cases in people who did not attend for follow up investigations.

Question 7

LO1 - Understand the theory behind any population screening programme.

What are the Screening steps?

Answer 7

• Identify population at risk.
• Decide how often to screen.
• Invitation list.
• Attendance of individuals.
• Undertaking test.
• Diagnostic confirmation.
• Referral system.

Question 8

LO2 - Understand how the performance of screening tests is assessed.
NOTE: SCREENING TESTS ARE NOT DIAGNOSTIC

1. What characteristics should a screening test have?
2. What is sensitivity?
   
   1. What will a highly sensitive test have?
3. What is specificity?
   
   1. What will a highly specific test have?

Answer 8

1. should be cheap, quick and acceptable. In addition, it should be reliable and valid while measured with sensitivity and specificity.
2. Sensitivity - measure of ability to detect disease when present.
   
   1. no or very few missed cases (false negatives).
3. measure of ability to identify healthy people as non-diseased
   
   1. no or very few false positives

Question 9

LO3 - Be able to outline the principles of screening programme evaluation

Negative effects of screening and potential for over diagnosis

​Give the negative effects

Answer 9

• Hazards from screening test
• Reliance on false negatives
  
  • Ignoring symptoms.
• Anxiety & additional tests for false positives.
• Opportunity Costs.
• Creating ‘patients’ from well people.
• Anxiety & interventions in those whom disease will never kill.
• Risk from interventions
• Anxiety in those who choose to ignore invitation.
• Misclassification of ‘borderline’ lesions.
• Diagnosis of non-progressive disease e.g. prostate cancer.
• Diagnosis of in situ disease.

Question 10

LO3 - Be able to outline the principles of screening programme evaluation

Monitoring screening programmes

1. What you monitor depends upon what?
2. What is the overall aim?
3. What should montioring involve?

Answer 10

1. timescale.
2. decrease mortality, decrease incidence (if screening for pre-disease state e.g. cervical cancer.)
3. Monitor process, response rate to invitation, number of false positives etc Monitor numbers and stage of disease. Monitor outcomes - survival. QALYS, DALYS.

Question 11

LO3 - Be able to outline the principles of screening programme evaluation

Quality assurance

1. describe the opportunity costs
2. How can quality assurance be assured?

Answer 11

1. should be economically balanced in relation to expenditure on medical care as a whole.

2.

• Plan for managing and monitoring the screening programme and an agreed set of quality assurance standards.
• Adequate staffing and facilities - should be available prior to the commencement of the screening programme.
• All other options for managing the condition should have been considered - improving treatment or providing other services

Question 12

LO4 - Know of the major types of population screening programme in the NHS and who is responsible for commissioning them

Current NI screening programmes

1. What cancer screening is carried out?
2. What vascular screening is carried out?
3. What new-born screening is carried out?
4. What antenatal screening is carried out?

Answer 12

1. Breast, Cervical, Bowel cancer
2. Diabetic retinopathy, AAA
3. New-born hearing, New-born bloodspot
4. Antenatal infections

Question 13

LO4 - Know of the major types of population screening programme in the NHS and who is responsible for commissioning them

E.g. Colorectal cancer screening

2nd most common cause of cancer death in men & women with 1000 cases/year and 400 deaths/year in NI.

1. What screening test is carried out? What does this involve?
2. What is generated for positive results?
3. What much each person in the programme be aware of?
   
   1. give examples of people involved in the programme

Answer 13

1. Faecal occult blood test - 2 samples from three bowel motions on separate occasions, Sent to bowel screening lab
2. There is a pathway generated for positive results with referral for assessment, endoscopy/radiological investigations and final management.
3. of their responsibility.
   
   1. These include individuals, teams, Trusts, BSO and the public health agency.

Question 14

LO4 - Know of the major types of population screening programme in the NHS and who is responsible for commissioning them

Genetic screening

1. What is genetic testing?
2. What impact may the predictive nature of the test have?
3. What is there a risk of?
4. What is required in terms of participation?
   
   1. What could this mean?

Answer 14

1. The analysis of alterations resulting from inherited mutations (not somatic).
2. Predictive nature - prolonged anxiety - psychological impact
3. Risk of discrimination - employees and insurance companies.
4. Familial nature - need participation of more than one relative.
   
   1. Implication of results for other relatives.