Prevention and screening Flashcards
What is primary prevention? Give an example
preventing disease before it occurs Examples: - education - immunisation - fluoridation of water
What is secondary prevention? Give examples
Detects early disease to alter course or prevent recurrence of disease
Examples:
- breast cancer screening
- aspirin to prevent further MIs
What is tertiary prevention?
Give examples
Reduce impact of disease, improve QOL or function
Example:
- rehab post stroke
What is the prevention paradox?
If something brings a lot of benefit to the population, then it provides little benefit to each individual
What type of prevention is screening?
Primary or secondary
What are the criteria for screening called?
Wilson and Jungner
What are the criteria for screening regarding the condition?
- Should be an important problem
- Natural Hx should be well understood
- Should be a detectable early stage
What are the criteria for screening regarding the treatment?
- Should be acceptable rx
- Facilities for diagnosis should be available
- Adequate health service provision should exist for people found positive on screening
What are the criteria for screening regarding the test?/
- Suitable test should exist for early stage
- Should be acceptable
- Should be repeated
What are the criteria for screening regarding risks and benefits?
- Should be an agreed policy on whom to treat
- Costs should be balanced against benefits
- benefits should outweigh the risks
What are current screening programmes?
- Guthrie/Heel prick test
- Newborn hearing screening test
- Breast cancer screening
- Cervical cancer screening
- Bowel cancer w fecal occult blood 60-74
- AAA - men >65
- Diabetic retinopathy screening - yearly
When is screening performed in cervical cancer?
every 3 years 25-50
every 5 years 50-64
What types of HPV does the vaccination work against>
6,11,16, 18
What types of HPV are high risk?
16 and 18
What is the combined test in antenatal screening>?When is it done?
Measure of nuchal translucency, PAPP-A and bHCG
10-14weeks
What is the quadruple test in antenatal screening? When is it done?
Same as combined but doesn’t involve NT,
Is done either 10-14 weeks if can’t retrieve NT due to baby position or 14-20 weeks
What condition does the quadruple test screen for?
downs
What does the combined test screen for?
work out the chance of the baby having Down’s, Edwards’ or Patau’s syndromes
What maternal infections are screened for in pregnancy?When are they tested for?
hepatitis B, HIV and syphilis.
usually at booking ~10 weeks
When is the anomaly scan done in pregnancy?
20 weeks
What newborn screening is done?
newborn hearing
newborn physical exam
Guthrie
What conditions does the Guthrie test look for?
Sickle cell Congenital hypothyroidism CF phenylketonuria Homocysteinuria MCADD
What is a false positive?
Result says they have disease when they DONT
What are false negatives?
When someone is screened for a disease and they are deemed not to have the disease but go on to develop it later on
What is sensitivity?
The proportion of people with a disease who are CORRECTLY identified by a screening process
Therefore: true +ve/true +ve + false -ve
What is specificity?
proportion of people without the disease who are correctly excluded by the disease process
Therefore: true -ve/true -ve + false +ve
What is positive predictive value?
Proportion of people who have a +ve screening result who following tests have the disease
Therefore: true +ve + false +ve
What is negative predictive value?
Proportion of people w a negative result who don’t have the disease following testing
Therefore: true -ve + false -ve
What are disadvantages of screening?
over detection of sub clinical disease
SE of screening
anxiety of patients
