Exam 2: Cohort Studies Flashcards
What are observational studies?
Explanatory type studies in that the goal is to assess cause
Sometimes called “natural studies”, as they occur freely in nature
Feature controls and planned comparisons between groups
What is a cohort?
A group sharing a defining characteristic
Describe cohort studies
Prospective in time (from now to the future)
Feature 2 cohorts: one exposed to a factor and one not exposed to that factor
Subjects are followed in time and incidence of one or more disease are compared between the 2 cohorts
What is the primary measure used in cohort studies?
Simple cumulative incidence
How are 2x2 tables contructed?
We put the exposure in the left column
We put disease (the outcome) in the top row
The positives go together
What does a cohort study intend to do?
Observe outcomes following a defined exposure
What are we measuring in cohort studies?
Incidence of disease
What is the measure of association in cohort studies?
Relative risk, which is just the risk of disease in exposed/risk in unexposed
What does a relative risk greater than 1 indicate?
An increased risk in exposed compared to unexposed
What does a relative risk equal to 1 indicate?
The risk in exposed is the same as the unexposed
What does a relative risk less than 1 indicate?
That disease in exposed is less than in unexposed
Exposure has a “sparing effect” or a reduction in risk associated with exposure, such as exposure to vaccinations
What is relative risk?
Measure of the strength of association between a factor and a disease
When can relative risk be estimated?
Only in a cohort, cross-sectional, or experimental study
Cannot be estimated in a case-control study
What are cohort studies well suited for?
Studying disease and exposures that occur relatively commonly
Study the effect of multiple outcomes following a single exposure
Look over examples
Look over examples
