A study which involves identifying patients who have the outcome of interest (cases) and control patients who do not have that same outcome, and looking back to see if they had the exposure of interest.
The exposure could be some environmental factor, a behavioral factor, or exposure to a drug or other therapeutic intervention.
A retrospective observational study in which the sample population is made of two groups: the case group and the control group.
The case group consists of people with the outcome (or disease) being studied and the control group consists of people without the outcome.
Retrospectively, the researcher determines the individuals exposed to the risk factor in each group.
Case-control studies: key points
- Case-control studies are simple to organise
- Retrospectively compare two groups
- Aim to identify predictors of an outcome
- Permit assessment of the influence of predictors on outcome via calculation of an odds ratio
- Useful for hypothesis generation
- Can only look at one outcome
- Bias is a major problem