What is a retrospective observational study?

A retrospective study is an observational study that enrolls participants who already have a disease or condition. In other words, all cases have already happened before the study begins.

What study design is a retrospective study?

A retrospective study uses existing data that have been recorded for reasons other than research. A retrospective case series is the description of a group of cases with a new or unusual disease or treatment.

How do you know if a study is retrospective or prospective?

Prospective vs retrospective studies

  1. In prospective studies, individuals are followed over time and data about them is collected as their characteristics or circumstances change.
  2. In retrospective studies, individuals are sampled and information is collected about their past.

What is an example of a retrospective study?

Retrospective example: a group of 100 people with AIDS might be asked about their lifestyle choices and medical history in order to study the origins of the disease. A Second group of 100 people without AIDS are also studied and the two groups are compared.

What level of evidence is a retrospective observational study?

For a retrospective cohort study, Level of Evidence = III. If you design the study or formulate the question(s) to be answered after the data are collected, then the study is still retrospective.

What level of research is a retrospective study?

A cohort study can be prospective (researchers formulate their hypothesis before data collection). For a prospective cohort study, Level of Evidence = II. Or a cohort study can be retrospective (researchers formulate their hypothesis after data collection). For a retrospective cohort study, Level of Evidence = III.

What type of experiment is an observational study?

Observational studies are ones where researchers observe the effect of a risk factor, diagnostic test, treatment or other intervention without trying to change who is or isn’t exposed to it. Cohort studies and case control studies are two types of observational studies.

Is a retrospective cohort study an observational study?

Cohort studies are observational. This means scientists observe what happens to a group of people without intervening. This allows researchers to study potential risk factors for disease as they naturally occur.

When is a retrospective study used?

In general, the reasons to conduct a retrospective study are to:

  1. Study a rare outcome for which a prospective study is not feasible.
  2. Quickly estimate the effect of an exposure on an outcome.
  3. Obtain preliminary measures of association.

What are retrospective studies used for?

Retrospective studies help define prognostic factors to be used so that the therapeutic strategy may vary depending on the predicted risks. Those studies are extremely helpful to assess the feasibility of prospective studies and to help in their design.