Screening

• What is population screening?


  Applied to an entire population or a broad segment of it, typically based on demographic factors like age or gender

  Primary aim: identify individuals with a particular condition or risk factor within a general population. reduce burden of disease & prevent its spread
• What is targeted screening?


  Focused testing on high-risk individuals (e.g. individuals who smoke are at higher risk of developing lung cancer regardless of their age or sex)
• What does screening aim to do?


  Prevent earlier deaths or improve QoL by detecting a condition at a stage where treatment can be more effective

  Reach everyone in target population

  Reduce the chance of people developing a serious condition or its complications

  Provide info for people to make informed choices
• What are the current UK population screening programmes?

  AAA

  Bowel cancer

  Breast

  Cervical

  Diabetic eye

  Foetal anomaly

  Infectious diseases in pregnancy

  Newborn & infant physical examination

  Newborn blood spot

  Newborn hearing

  Sickle cell & thalasseamia
• What is the generic screening pathway?


  Identify people to invite

  Discuss & offer screenig

  Carry out screening test

  Provide & discuss results/options

  Carry out diagnostic tests (if required)

  Provide & discuss results/options

  Offter advice/treatment
• What are the benefits of public health screening?


  Reduced morbidity, mortality and/or disability

  Protect the population from exposure to disease (travelers/immigrants screened for HIV/Hep B)

  More effective treatment

  Informed decisions
• What is a false negative?


  a test result indicating a person does not have a raised chance of the condition but in fact they do have the condition
• What is a false positive?


  a test result indicating a person does have a higher chance of the condition whereas in fact they do not
• What are the downsides of screening?


  Incorrect results (anxiety or false reassurance)

  Physical harm

  Psychological harm

  Financial harm

  Overdiagnosis
• What is the role of epidemiology in screening?


  Identify whether disease has an appropriate 'natural history' to make screening an option

  Conside if disease presents a significant burden

  Measure test quality & estimate how it might perform in the population

  Assess the potential of a screening programme to improve outcomes

  Evaluate performance of a screening programme in practice
• What is the role of health economics in screening?


  Cost-effective analysis

  • Measuring costs (direct/indirect/long-term healthcare costs)
  • Measuring benefits (health gains)
  • Incremental cost-effectiveness ratio (ICER)
• Screening should always be a personal informed choice.
• What are the possible inequalities in screening?

  Cohort identification (invitation)

  Provision of information about screening

  Access to screening services

  Access to treatment & onward referral

  Outcomes
• What are the possible barriers to screening?


  Accessibility

  Stigma

  Embarrassment

  Lack of social support

  Fear of outcome

  Low perceived risk

  Knowledge

  Lack of time