retrospective cohort study vs case control

#Retrospective cohort study vs case control series#

Often case-control studies require the participants to self-report their exposure to a certain factor.

Nevertheless, as case-controls are retrospective, they are more prone to bias. Furthermore, you can assess multiple exposures to get a better understanding of possible risk factors for the defined outcome / disease. The fact that the analysis is retrospective, allows rare diseases or diseases with long latency periods to be investigated. It may even increase statistical power and study precision by choosing up to three or four controls per case (2).Ĭase-controls can provide fast results and they are cheaper to perform than most other studies. age, sex) to ensure these do not confound the study results. It is possible to match controls to the cases selected on the basis of various factors (e.g. Regardless of how the cases are selected, they should be representative of the broader disease population that you are investigating to ensure generalisability.Ĭase-control studies should include two groups that are identical EXCEPT for their outcome / disease status.Īs such, controls should also be selected carefully. An inherent issue with selecting cases is that a certain proportion of those with the disease would not have a formal diagnosis, may not present for medical care, may be misdiagnosed or may have died before getting a diagnosis. The main outcome measure in case-control studies is odds ratio (OR).Ĭases should be selected based on objective inclusion and exclusion criteria from a reliable source such as a disease registry. This can suggest associations between the risk factor and development of the disease in question, although no definitive causality can be drawn. See Figure 1 for a pictorial representation of a case-control study design. They look back to assess whether there is a statistically significant difference in the rates of exposure to a defined risk factor between the groups. They clearly define two groups at the start: one with the outcome/disease and one without the outcome/disease. Case-control studiesĬase-control studies are retrospective. Although these studies are not ranked as highly as randomised controlled trials, they can provide strong evidence if designed appropriately.

#Retrospective cohort study vs case control series#

These types of studies, along with randomised controlled trials, constitute analytical studies, whereas case reports and case series define descriptive studies (1). Case-control and cohort studies are observational studies that lie near the middle of the hierarchy of evidence.