RESS Flashcards
(75 cards)
What is incidence and prevalence used for?
To compare the epidemiological triad
What is the epidemiological triad? (3)
- Time
- Person
- Place
What is incident rate?
Number of new case occurring in a period/ number of people at risk in a population.
(Those that can contract the disease)
What is prevalence?
Number of people in the population with the disease at a certain time.
What is prevalence useful for? (what disease type?)
Chronic disease
What is case fatality rate?
Number of people who die from the disease in a period/ number of people with disease
What is mortality rate?
number of people who die from the disease in period/ number of people who die in period
What is adjustment?
reducing the effects of the population factors that may sway the result.
example - age adjustment
How is age adjustment done?
By stratum specific rates
- The study divides different categories of age and sex.
- Incidence of each group is calculated
- standardised weightings are assigned to the groups - based on this data is adjusted accordingly
How is the likelihood of a particular outcome measured?
Risk and odds
What is risk?
- the probability of disease
1 = Certain to happen
0 = Will not happen
- number of new cases/ number at risk
Why can’t you assign a personal risk?
As the person is either going to get the disease or not.
- can assign a group lifetime risk
e. g. Heavy smokers risk of developing lung cancer
What is a risk ratio?
Comparison of risks between 2 groups
- risk in exposed group vs risk in unexposed group
When is a risk ratio used?
In cohort studies only
What is a cohort study?
- Investigates the causes of disease, establishing links between risk factors and health outcomes.
- Cohort studies are usually forward-looking - that is, they are “prospective” studies, or planned in advance and carried out over a future period of time.
e. g testing new drug - half get new drug and half get current treatment
How are cohort studies selected?
By their exposure
What is calculated in a cohort study?
Incidence of disease
- those of the cohort that smoke and how many of them got lung cancer at the end of the study
What is the risk ratio a measure of?
Of relative risk
What does it mean if the relative risk = 1?
no difference between the 2 groups
- risk / odds is the same in exposed and control group
What does it mean if the relative risk is
exposure is protective
risk / odds in exposed group is less than in control group
What does it mean if the relative risk > 1 ?
exposure is harmful
risk/odds in exposed group is greater than in control group
What is the relative risk?
Risk for treated group/ Risk of control group x 100
What is the relative risk reduction?
100 - relative risk
What is the risk difference?
0 = there is no risk difference between unexposed or exposed