Sample Paper on Describe common characteristics and design of a case-control study

A case-control study is a way of comparing patients who have a disease (case) with the ones that do not possess the condition (control) and look back to analyze how frequently the exposure to a risk factor is present in each group to establish the relationship between the risk factor and the disease. It is also known as a retrospective study.

Common characteristics include:

A case-control study is retrospective; they clearly define two groups, one with the disease and one that does not have the disease to establish a relationship between the two.

The case-control study provides fast results compared to other methods; the fact that they are retrospective allows one to investigate diseases that are rare or have a long latency period.

Discuss three important features when it comes to selecting cases and controls and identify a situation when one of this might be violated.

The comparison group should be representatives of the source population that produced the case; controls should be representatives of the people where the case was formulated.

The controls can carry the same disease as the cases but of another grade henceforth being different from the out of interest.

The number of cases and controls do not have to be equal. Therefore, more control can be acquired compared to the number of cases since, in many situations, it is easier to find control than to find a case.

The principle that states the number of controls and cases can be violated, but when violated, the outcome of the research will be biased.

Discuss limitation of using questionnaire to determine exposure status and provide example of alternative strategies for collecting this information in case-control study.

The main limitation of using questionnaires as a way of determining exposure is recall bias (Le Moual et al. 2000). There is also a limit on how much can be asked in a single questionnaire. In addition to that, asking subjects about exposures in the questionnaire will assume that the subject will distinguish between exposure agents and their own exposure, this issue results in poor responses.

The other alternatives used to collect data in the case-control study are environmental samples and predictive models, whereas environmental samples are considered to be the most precise way.