Introduction to epidemiology Flashcards
What are mortality rates?
the number of deaths in a given area or time period or from a particular disease
What statistics are needed for mortality rates?
- a dominator population
- timeframe
How is the incidence rate calculated?
no. of new people with outcome over a time period / total person-time for people in a group at risk
x 100,000
What is incidence?
number of new cases
What is prevalence?
proportion of population that has a disease
What are the two types of prevalence?
point
period
How is point prevalence rate calculated?
no. of people with outcome at a point in time / total number of people in the group
x 100
How is period prevalence rate calculated?
no. of people with outcome during a time period / average number of people in group
x 100
What does sporadic mean?
occasional cases occurring irregularly
What does endemic mean?
persistent background level of occurrence
What does epidemic mean?
occurrence in excess of the expected level for a given time period
What does pandemic mean?
epidemic occurring in or spreading over more than one continent
What are the different types of exposures?
no-modifiable
modifiable
interventions
How is the risk calculated?
number of outcomes in a group / number of people in the group
x 100
How is relative risk calculated?
risk in exposed / risk in unexposed
How is relative risk reduction calculated?
(1 - relative risk) x 100
How is absolute risk reduction calculated?
risk in unexposed - risk in exposed
How is number needed to treat calculated?
1 / absolute risk reduction
How does the hierarchy of evidence work?
those at the top of the pyramid are more likely to influence clinical practice
How does a cross-sectional study work?
- sample a population
- estimate the proportion
- use data
How does a case-control study work?
- select cases with an outcome
- select controls without an outcome
- explore exposures in cases and controls
- compare exposures to work out cause
How does a cohort study work?
- select people without an outcome
- classify according to exposure
- compare risk of disease in exposed and unexposed
How does a randomised controlled trial work?
- random allocation
- compare risk or outcome in intervention and control groups
- used to test new drugs
What is a confounding variable?
one which can cause disease under study and also associated with the exposure of interest
