Case-Control Studies Flashcards
What kind of studies are case-control studies?
Observational
What is a case-control study?
Observational study that allows the researcher to be a passive observer of natural events occurring in individuals with a condition (case) compared to those who do not have the condition (controls).
How are group assignments base in Case-control studies?
On disease status
What type of study is useful when studying a rare disease or investigating an outbreak?
Case-Control Study
What type of study commonly generates an Odds of exposure and Odds ratio?
Case-Control
What are Reasons to select a Case-Control Design?(4)
- Unable to force group allocation
- Limited resources
- The disease of interest is rare and little is known about its associations
- Prospective exposure data is difficult/expensive to obtain.
Case-Control studies are customarily conducted in a ___ fashion?
Retrospective
Strengths of Case-Control studies (6)
- Good for assessing multiple exposures of one outcome
- Useful when diseases are rare
- Useful in determining Associations (NOT causation)
- Less expensive than interventional trials and prospective cohort studies.
- Useful when ethical issues limit Interventional studies
- Useful when disease has a long induction/latent period.
Weaknesses of Case-Control Studies (5)
- Can’t demonstrate Causation
- Can be impacted by unassessed Confounders
- Retrospective
- Can be impacted by various biases(selection and recall/Assessment biases)
- Limited by available data (retrospective nature of design.)
How should cases be selected?
Objectively, Consistently, Accurately, and with Validity using medically-reliable, efficient data sources.
What is the risk of classifying patients?
Misclassification/Sensitivity/Specificity/PPV/NPV/Diagnostic Accuracy
What is Counterfactual Theory?
All else being equal, the outcome if something didn’t occur.
What does counterfactual theory require for some things?
Exchangeability which equals comparability
What is the most difficult part of Case-Control studies?
Control Selection
What is the goal of control selection?
Assess the presence of an association between expose and a known condition by selecting non-diseased individuals from the same population of the cases.
What is a major determinant in whether any conclusion is valid? (internal validity, Selection bias)
Control selection
Controls must be selected irrespective of what?
Exposure status
What are the three examples of sources control groups can come from that Dr. Segars gives in lecture?
- Population (State/Community/Neighborhood)
- Institutional/organizational/provider
- Spouse/Relatives/Friends
What is outbreak-sources of control?
Participants participated in the same event.
What should you ask yourself when looking at a case-control study?
Who are the case subjects and Who are the control subjects.
In what kind of study can an individual function as both an expose and unexposed individual?
Case-Crossover. Subjects are their own controls during the other times they don’t have the acute change in risk.
What is the only Case-Control design able to adequately attempt to address the issue of Temporality?
Case-Crossover.
What are nested Case-Control Studies?
These are Case-Control studies conducted after, or out of, a prospective previous study-type.
What are the selection of controls used for Nested Case-Control studies when sampling from previous other study-type (Cohort/Interventional)
- Survivor sampling - Sample of non-diseased individuals at the end of the study
- Base sampling - Sample of non-diseased individuals at start of study period
- Risk-Set sampling - Sample of non-diseased individuals during study period at same time when case was diagnosed.
