Question

You are an epidemiologist concerned about the relation between toxic waste exposure and nervous system disorders. You decide to conduct a case-control study. Feel free to use your imagination and be creative!

Describe how you would:

Obtain your cases and controls.

Collect information on the outcome (nervous system disorders). For example, pre-existing records, self-reporting, direct measurements, surveys, etc.

Collect information on the exposure (to the toxic waste).

What are the advantages of using a case-control study to investigate this problem?

Answer 1

to study realtion between toxic waste exposure and nervous system disorders case control study is important method for the study.

Case-control study is the observational epidemiologic study of persons with the disease of interest and a suitable control group of persons without the disease.

In this study difference in two study groups is observed and later analysed, but it is not by experimentation. It is useful to determine if two groups differ in exposure to factors

A case control study involves two populations – cases and controls.

Before beginning of the study exposure and outcome have occurred.

The study proceeds from effect to cause

It uses a control to support an inference.

Case is defined as a person in the population or study group identified as having the particular disease, health disorder or condition under investigation.

Control is defined as Person or persons in a comparison group that differs, in disease experience in not having the outcome being studied

Obtain your cases and controls.

Cases are randomly selected in the source population and their information is collected.

Selection can be done from incidence or prevalence case. Diagnostic criteria for case studies include Specificity, Diagnostic bias, Validation

Controls are Selected similar to the cases in all respects other than having the disease (Comparable) Controls should be representative of all non-diseased people in the population from which the cases are selected (Representative)

Controls must be selected in the same way as the cases.

The study base is composed of a population at risk of exposure over a period of risk of exposure.

Information can be collected on the outcome (nervous system disorders) like pre-existing records, self-reporting, direct measurements, surveys etc. Information is also collected on the exposure to the toxic waste and disease occurrence was studied.

Advantages

Case-control approaches are very much useful for study of rare diseases.

It is inexpensive compared to others

Only realistic study design for uncovering etiology in rare diseases

Significant in understanding new diseases

Commonly used in outbreaks investigation

Beneficial if inducing period is long