Prevention Flashcards
Define Primary Prevention
Preventative interventions aimed to avoid development of an outcome altogether by reducing the risk of exposure in a population.
E.g. Vaccination, Road safety laws etc.
Primary prevention may need new legislation or societal shifts in attitudes.
Define Secondary Prevention
Preventative interventions that aim to halt or slow the progression from early outcome stage to mid-outcome stage by early detection and early, effective treatment. People can be asymptomatic or sub-clinical.
E.g. Screening for breast cancer
Define Tertiary Prevention
Occurs after the outcome has developed and aims to improve the prognosis and reduce complications of the outcome by given appropriate treatment etc.
E.g. Making anti-clotting meds available for post-stroke recovery.
Name 2 preventative approaches
- High Risk Approach (individual, relative risk) e.g. mammograms to women over 50 due to cost and risk
- Population Approach (absolute risk) e.g. flouride tablets in populations water supply.
Outline a high risk approach
- ID high risk population
- Reduce exposure to outcome of interest
- Reduces their relative risk
- Often occurs when an intervention is expensive and resources are limited.
- Those at greatest risk of developing an outcome may be more willing to comply with a preventative intervention.
What are the limitations of a high risk approach to prevention?
- Risk of the outcome vs. intervention effect can vary in different risk groups.
- May not allow individuals to make informed decisions re compliance with an outcome
- Being labelled high risk can lead to stigmatization and excess anxiety and stress.
- Does not always address the source or cause of the issue e.g, vaccinating against waterborne diseases without improving water source quality.
OR Using cholesterol lowering drugs without improving diet. - Criteria should be standardized to prevent blurring High risk categories.
Outline a population approach to prevention
- reduces absolute risk of an outcome by reducing exposure to a risk factor.
- Note: for many outcomes, individuals are exposed to varying degrees rather than well defined ‘exposed’ and ‘unexposed’ groups.
- Note: population measures make sense for many outcomes because many people exposed at lower levels of risk may lead to more cases than less people exposed at higher levels of risk. (Think levels of pyramid in ISSUES module - more evidence for widespread vs targeted in some settings)
E.g. Lowering BMI on a population basis (maybe through food composition) rather than targeting only obese people with interventions.
What is the prevention paradox?
Name the author and year also
ROSE, 1992 Describes how large benefits to the community through population health measures may bring limited benefits to the individual.
Social pressures or economic incentives can increase compliance with health promotion activities that have no obvious gain to individuals.
E.g. laws making cyclists wear a helmet are beneficial to cyclists when in an accident (limited gains) vs. community wide drop in bicycle related head injuries.
How do we choose which preventative approach to take?
- Use population attributable fraction to choose which approach is more appropriate.
- Look at the dose-response relationship to determine how the risk of outcome changes with the level of exposure. Shape is NB.
- Note: its often best to use a combination of approaches.
Describe shapes of the dose-response relationship?
e.g linear, threshold, curved linear, Jshaped
Threshold: Best to target people close to the threshold e.g. glaucoma thresholds.
Linear: The greater the exposure, the greater the risk, even at low exposure levels. Population level approach mst effective here usually through legislation and health promotion activites that shift the whole pop exposure to low levels.
Example: lung cancer and cigarette smoke.
Curved linear: more realistic than linear at times. Risk of outcome increases with increased exposure but is lower at lower levels and higher as the exposure levels increase.
Example: maternal age and the increase risk of Downs Syndrome. or Osteoporosis related hip fractures and meds.
Note: if a large proportion of outcome comes from those at high risk - High Risk approach.
Note: if large proportion of outcome comes from low risk - population approach.
J-shaped: most complex. Increased risk of outcome when exposure is low and high, but a range of exposure levels where there is no risk of outcome. Ie. extremes are bad, moderation is good. A mix of approaches is appropriate here.
Example: Low bodyweight and high BMI vs normal BMI.
