Sources of Cases & Controls in an Epidemiological Study

Written by MicroDok

Cases and controls are important when anticipating or conducting an epidemiological study. This is because both controls and cases are factors that can be used to compare and contrast on the outcome of the epidemiological study. These factors (i.e. cases and controls) helps the researcher or investigator to evaluate properly, the outcome of any experiment or study conducted in a given locality or population. In this section, the sources of both controls and cases for an epidemiological study are briefly highlighted in this section.

Cases in an epidemiological study can be sourced in any of the following ways:

  • Data from hospital registries, clinics and disease screening records.
  • All cases diagnosed in a particular hospital department at a given time.
  • All cases diagnosed in the community/population.
  • All cases diagnosed in all hospitals (public or private).
  • All cases diagnosed in a sample or fraction of the population/community.


Controls in an epidemiological study can be sourced in any of the following ways:

  • Samples of patients who do not have the disease under study in all hospitals.
  • Samples from members of the general community/population who are at risk for the disease as the cases.
  • Relations, spouses, children or companions of the cases.
  • Samples of patients in the same hospital where cases were obtained from and, who do not have the disease.
  • Non-cases in a sample of the community/population.


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