Epidemiology 2 Flashcards
(65 cards)
What is a primary prevention strategy?
The aim of a primary prevention strategy is to prevent the disease from occuring upstream at the first stageb but reducing the exposure or risk factors.
Example of primary prevention public health strategies?
Health promotion for healthy lifesyle e.g. healthy diet and stop smoking etc.
Fluoridation of drinking water
Childhood immunisation programmes
population level legistlation e.g. illegal to smoke in public places and plain packaging.
What is secondary prevention?
To aim to detect the disease early in order to decrease the progression/severity of the disease or stop the disease recurring
Examples of secondary prevention strategies?
Screening for diseases e.g. smear tests for cervical cancer, or mammograms to see if breast cancer.
Treatment with a drug to reduce further risk e.g. aspirin after heart attack stop another, give a pacemaker.
What is Tertiary prevention?
To minimise the impact after the event has happened by minimising disability and preventing complications.
Examples of tertiary prevention strategies?
Preventing death- e.g. in hopsital after a heart attack.
rehabilitation after a stoke.
A&E services after a crash
Car crash primary secondary and tertiary prevention strategies?
Primary: to stop the event e.g. speed limits, laws to ban drink driving, going on phones etc.
Secondary: Not stop event but reduce severity e.g. carseats for children, airbags, car crumple zones
Tertiary: stop death e.g. At A&E treatment, bandage wounds etc
How ar ethe primary, tertiary and secondary prevention strategies split further into 2? (examples)
Individual or population strategy
E.g. population strategies would be laws, health promotion activites, initiatives, screening programmes.
Individual strategies specific to individual e.g. identiying those high risk of diabetes- give healthy eating couselling, specific tests, drugs given to prevent further complications/death.
What are high risk approaches to prevention?
Involves identifying those at high risk and then tailoring the action for them- reduce exposure or provide a protection to.
Advantages of high risk approaches to prevention? (3)
- Focuses only on those at high risk, so has a high rate of return.
- Method chosen for the individual so likely to be appropriate and motivate them more.
- Physician motivated to help individual.
What is the prevention paradox?
A population prevention strategy which overall brings much benefit to the population (e.g. saves 300 lives a year), but if this is per 100,000, then 99,700 people will have no benefit.
What is risk compensation?
When the prevention method is counterrracted by other actions e.g. cyclist wearing helmet so cars see them as safer and may get closer. Or person on statins then eating more Cholesterol fatty food.
Advantages of population strategies? (3)
- Large potential for the population- doesn’t miss anyone at say medium risk.
- Behaviourally appropriate
- Doesnt involve screening for high risk people to target as just target everyone.
disadvantages of population strategies? (3)
- Small benefit to most people- cost benefit analysis may be low.
- Poor motivation of individual or physician
- Can make health inequality worse- say healthy food and gym- more expensive and educated may see value more.
disadvantages of high risk approaches to prevention? (4)
- Involves screening people- costs, recruiting people?
- Limited effect as it misses most of the popualtion. E.g. medium risk may hold most of the population so save the most lives, even if some people are at higher risk.
- Effects may be temporary- individual initially motivated to change but revert back.
- Now less public health more medicine.
WHat is a screening test?
A process which sorts apparently well people into those who probably have the disease (or precursors/susceptable to) from those who probably dont.
Different to a diagnostic test which is a simple test that says yes or no.
Is a screening test primary, secondary or tertiary prevention?
Either primary or secondary.
E.g. Primary for breast cancer- genetic test have associated BRCA gene. Will be high risk- show susceptability.
E.g. Secondary for breast cancer- mammography- when no symptoms catch it early so can treat and stop progression.
Tertiary- will have symptoms so likely know have the disease so no point screening.
How can we measure the efficiency of screening? (5)
Sensitivity, specificity, Positive predictive value, Negative predictive value, accuracy.
What is the sensitivity of a test?
The probability of someone with the disease having a positive test result. Left column.
True positive/ all with disease.
What is the specificity of a test?
The probability of someone without the disease having a negative test result. Right column.
True negative/ all those without disease.
How are specificity and sensitivity usually related?
As the sensitivity increases, the specificity decreases. E.g. if the cut off for diagnosis is brought down, even more people with the disease will be identified, but also more wwithout the disease will get a positive result. So a balance is needed- if plot 1-spec vs sensitivity on a graph- the most top Left point- or add the two values and pick the highest number.
What is a positive predictive value?
The probability that an individual with a positive test will have the disease.
Top column- True positive/all test positive
WHat is a negative predictive value?
The probability that an individual with a negative test will not have the disease. Bottom column.
True negative/ all test negative
Accuracy of a screening test measured?
correct diagnosis/total screened.
