Evidence for population and health Flashcards
define epidemiology
is the study of the distribution and determinants of disease
what is a anecdote or case series
story, not fact
define case series
more than 1 person with a disease
a type of medical research study that tracks subjects with a known exposure, such as patients who have received a similar treatment,[1] or examines their medical records for exposure and outcome.
MMR.
what are the pros of a anecdote study
- Quick
- Easy to perform in a clinic
- Provides new previously unobserved conditions
- Provides new potential risk factors.
what are the cons of a anecdote study
- Not scientific- not able to test hypothesis
- Seriously affected by observer bias
- Difficult to make inference about disease cause.
what is a cross sectional survey
Snapshot of people with an outcome.
what are the pros of a cross sectional survey
- Quick
* Good at estimating prevalence or burden
what are the cons of a cross sectional survey
- Only represents that point in time
- Cannot estimate incidence
- Sampling frame may lead to bias (e.g missing “workers”)
define prevelance
number of people have that disease at that point in time, typically measured as a percentage.
define incidence
The number of new cases of the disease
define analytical epidemiology
Woking out the determinants of disease in a population.
What are the characteristics of the cause of a disease
- The cause must occur before the outcome.
* You cannot see a cause of the disease.
define counterfactual method
- If you kept all the variables the same but removed the cause of a disease would the disease still occur?
- In reality you cannot create this situation as you would need 2 identical worlds, but it is a good tool for a thought experiment.
define ecological study
Unit of observation is a group.
• Comparison of 2 populations- e.g. in 2 different areas.
pros of ecological study
- Less expensive
- Less prone to bias due to participation
- Easy to perform using routinely collected data
- Provides new hypotheses about the causes of a disease or condition.
- Provides new potential risk factors.
cons of ecological study
- Ecological fallacy- do population measures hold for the individual?
- Assume average value of the risk factors applies to all individuals.
- Assume average incidence applies to all the individual applies to all the individual in a population.
- Data collection may vary e.g. coding systems.
what is the unit of observation in a ecological study
a group (not an individual)
what is the risk ratio in a case controlled study
disease in case/ disease in control.
what does a risk ratio of one mean
exposure increases the risk of disease
what does the risk ratio of less than 1
exposure lowers the risk of disease
how does a case controlled study work
looks at individuals with and outcome.
First, identify the cases (a group known to have the outcome) and the controls (a group known to be free of the outcome). Then, look back in time to learn which subjects in each group had the exposure(s), comparing the frequency of the exposure in the case group to the control group.
what are the pros of case controlled study
good for rare diseases
fairly quick
what are the cons of a case controlled study
prone to selection bias
especially prone to participation bias
finding a suitable control can be difficult
difference in recall
what is the best type of observation study
cohort study
