Flashcards in Introduction to epidemiology Deck (25):
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
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
What is incidence?
number of new cases
What is prevalence?
proportion of population that has a disease
What are the two types of prevalence?
How is point prevalence rate calculated?
no. of people with outcome at a point in time / total number of people in the group
How is period prevalence rate calculated?
no. of people with outcome during a time period / average number of people in group
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?
How is the risk calculated?
number of outcomes in a group / number of people in the group
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?
1. sample a population
2. estimate the proportion
3. use data
How does a case-control study work?
1. select cases with an outcome
2. select controls without an outcome
3. explore exposures in cases and controls
4. compare exposures to work out cause
How does a cohort study work?
1. select people without an outcome
2. classify according to exposure
3. compare risk of disease in exposed and unexposed
How does a randomised controlled trial work?
1. random allocation
2. compare risk or outcome in intervention and control groups
3. 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