Assignment: Case-Controlled Studies

Assignment: Case-Controlled Studies

Assignment: Case-Controlled Studies

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Basically, our reading assignment is concerned with the two studies or “designs” utilized

in Epidemiology. Both studies are concerned with a plethora of terminology which concerns

the studies as both are looking at risk factors and disease.

With Cohort studies the people selected (Cohort) are disease free. The Cohort group are

then defined as exposed to disease or not and are then followed over time to determine whether

new cases of disease develop. This is called outcomes or “cause” of disease.

Epidemiologists choose a health problem and try to figure out why some are more likely

than others to develop disease in comparison to other people based on reliable data. A Cohort

Study is an example of a study of prognosis and are usually for patients in the local area.

These studies should begin at zero time which is onset of symptoms, diagnosis

or treatment.  Otherwise they are considered inception cohort or onset of the disease. Follow-up

can be from weeks to years depending on the disease process and outcomes for prognosis should

consider the full range of the manifestation of the disease (Croft. P. et. al., 2015).

One example of a Cohort Study is the effects of those who drink alcohol or smoking and

what disease process does this cause over a time period? Is it bladder cancer or is it

lung cancer?  So, this is the impact of one type of Epidemiological Study.

The other study is concerning with Case-Controlled Studies. People with and without

disease (control group) are selected. The control group is the “population at risk” The difference

is if they have been “exposed to the risk or not.” This is where the Epidemiological Impact

comes in to study to calculate the amount of cases and those in the control group who were

exposed to the risk.

In reading about these studies and trying to wade through the terminology the thought

occurred to me, “how do they decide which study to use and why?”

Cohort Studies are used over a time frame…a long time, and provide the best information

about cause of disease and exposure. This is because those in the study are followed from the

time of exposure to disease process. The impact of Epidemiology here is outcome and cause of

disease over a long time frame. These are very expensive studies to conduct (personal

communication, J. Keltz, PharmD, 2017).

Case-control studies are easy to conduct, do not require an extended time frame for

follow up and therefore, are much cheaper. Cancer would be a good example of a case-control

study; however, this study is less likely to show “cause” of disease and are more prone to bias.

The case-control studies are quick, inexpensive, and easy to use.

Reference:

Croft. P., et. al. (2015). The science of clinical practice: disease, diagnosis or patient prognosis?

BCM Medicine. (pp. 1-8).

Fletcher, R.H., Fletcher, S.W., & Fletcher, G.S. (2014). Clinical epidemiology: the essentials.

            (5th ed). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkens.