Case-Control Studies Flashcards
What category of study design do case-control studies fall under?
Case-control studies are observational study designs and are analytical
How are groups assigned in a case control study design?
Groups are assigned based on disease status. Individuals with the disease/condition of interest (cases) versus individuals who do not have the condition of interest.
What is the most useful reason for using case-control studies?
Case-control studies are useful when studying a rare disease or investigating an outbreak.
What type of measurement is used for analyzing case-control studies?
Case-control studies commonly generates odds ratio (OR) as measure of association.
What is the exposed population and what is the control group comprised of?
The study was designed to study an correlation of hormone therapy use and breast cancer occurrence. The exposed group was designated as a group for women with breast cancer that received hormone treatment and was compared to a control group designated as a group of women that did not have breast cancer and also received hormone therapy.
True or False. The case-control study design commonly utilizes the 2x2 table.
True. The case-control study design commonly utilizes the 2x2 table for summary.
What are 4 benefits of using a case-control study design?
Case-control studies are beneficial when:
1) the researcher is unable to randomize subjects because of ethical, legality, and feasability reasons
2) limited on resources (money, time, subjects)
3) disease is rare
4) prospective exposure date, derived from prospective corhort study, is difficult/expensive to obtain and/or very time inappropriate
True or False. Case-control studies are always retrospective.
True. Case-control studies are always retrospective.
What are the 7 strengths of case-control studies?
- good for assessing multiple exposures of one outcome
- Example: when studying outcome of breast cancer you can study the correlation with exposure to HT or BC etc.
- useful when diseases are rare
- useful in calculating odds and OR’s (associations)
- Less expensive
- useful when ehtical issues limit interventional studies
- useful for dynamic population
- useful when disease has a long induction/latent period
What is the weakness of case-control study designs?
The weakness of case-control study design is misclassification. Misclassification is a bias where researchers misclassify subjects to influence a correlation.
What is the most difficult aspect of case-control design?
The most difficult part of a case-control study design is the control selection.
In theory, the idea is to assess for association between exposure and known condition of interest by selecting non-disease individuals from the sample population which produced the cases. The control should represent the baseline risk of exposure.
What point in case-control study design is there a change for compromise of internal validity of the study?
For case-control study designs the way controls are selected is a major determinant in internal validity of study.
The control should represent the baseline risk of exposure in the general or reference population.
Just to note….
Look for the word “randomization” because this means that the study is an interventional study and cannot be an observational case control study. But do not let “randomly selected” cause you to pick the interventional study because one can randomly select patients from a mass population of the diseased patient’s to participate in the case-control study.
What is the best way to select control subjects for the case-control study?
The best way is to make the control groups as close as possible to the exposed subjects EXCEPT that they do not have presence of the disease (outcome) of interest.
What will the odds ratio be if the exposure truly has no effect?
If exposure truly has no effect, then odds will be exactly the same for both groups and OR will be 1.0 (no difference).
