On what basis do you decide to choose a cohort design or a case-control design?Ĭohort studies provide the best information about the causation of disease because you follow persons from exposure to the occurrence of the disease. Then calculate the proportion of cases and controls that were exposed to the suspected water source. You determine which source of drinking water they had used. To come back to the example, you may compare children who present themselves at a health center with diarrhea (cases) with children with other complaints, for example acute respiratory infections (controls). Then the occurrence of the possible cause of the disease could be calculated for both the cases and controls. The exposure status to a potential cause of disease is determined for both cases and controls. The controls should represent people who would have been study cases if they had developed the disease (population at risk). A case-control study begins with the selection of cases (people with a disease) and controls (people without the disease). The same problem could also be studied in a case-control study. You can then calculate how many diarrhea cases there were among those children using the suspected water source and those using other sources of water supply (cumulative incidence of diarrhea). after two weeks whether the children have had diarrhea. Then you classify them as either using the suspected water source or other water sources.
children living in the same area, or attending the same clinic. You select a group of children under five years, either all children of that age in the village, a random sample taken from the population register, or e.g. The whole cohort is followed over time to see if the development of new cases of the disease (or other outcome) differs between the groups with and without exposure.įor example, you could do a cohort study if you suspect there might be a causal relationship between the use of a certain water source and the incidence of diarrhea among children under five in a village with different water sources. The people in the cohort are grouped by whether or not they are exposed to a potential cause of disease.
#RETROSPECTIVE COHORT STUDY VS CASE CONTROL FREE#
What is the difference between these two designs? And when should you opt for the one or the other? Cohort studiesĬohort studies begin with a group of people (a cohort) free of disease. Both study causal relationships between a risk factor and a disease. Two designs commonly used in epidemiology are the cohort and case-control studies.
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