Unit 07: Disease Frequency and Measures of Association (Part 2) Flashcards
Which of the following are measures of association in epidemiology?
A) Prevalence ratio, mortality rate, and relative risk
B) Relative risk, odds ratio, and incidence rate ratio
C) Incidence rate, mean difference, and odds ratio
B
What is the relative risk (RR) in epidemiology?
The ratio of the risk of disease in exposed individuals to the risk in unexposed individuals.
True/False): Relative risk can be calculated directly in cohort studies.
True
How do you interpret a relative risk of 1, greater than 1, and less than 1?
A) 1: No association; >1: Negative association; <1: Positive association
B) 1: No association; >1: Positive association; <1: Negative association
C) 1: Protective effect; >1: No association; <1: Increased risk
B
Why can’t relative risk be calculated directly in case-control studies?
Because case-control studies start with diseased and non-diseased individuals rather than exposed and unexposed populations, making incidence rates unavailable.
In case-control studies, the ____ is used instead of relative risk.
odds ratio
What is absolute risk?
A) The difference in risk between exposed and unexposed individuals
B) The risk of disease in a population
C) The ratio of risks in exposed vs. unexposed individuals
B
In a matched case-control study, a ____ pair occurs when the case and control have the same exposure history.
concordant
A ____ pair occurs when the case and control have different exposure histories.
discordant
In a matched case-control study, which pairs are ignored when calculating the odds ratio?
A) Concordant pairs
B) Discordant pairs
C) Both are used
A
Why are concordant pairs ignored when calculating the odds ratio in matched studies?
Because concordant pairs do not contribute information about differences in exposure between cases and controls.
What does a relative risk of 2 mean?
It means the risk of disease in the exposed group is twice the risk of disease in the non-exposed group.
In case-control studies, the OR is interpreted as the odds of ____ in the ____ group relative to the non-outcome group.
A) disease; exposed
B) exposure; outcome
C) exposure; exposed
B
(True/False): For rare diseases (prevalence <5%), the odds ratio closely approximates the relative risk.
True
(True/False): ORs < 1 are often associated with protective factors such as vaccination or wearing masks.
True
(True/False): IRR measures the ratio of incidence rates between exposed and non-exposed groups.
True
If IRR = 1, it indicates ____ between exposure and the outcome.
no association
Which component is essential for calculating IRR?
A) Relative risk
B) Time at risk
C) Odds ratio
B