prospective study

A study to evaluate the effects of exposure to a given intervention or factor, in which the subjects are divided into groups that are exposed or not exposed to the intervention or factor of interest before the outcomes have occurred.

Note: Randomized controlled trials are always prospective, but case-control studies never are. Cohort studies may be prospective or retrospective.

Related concept: cohort study.†

Ant.: retrospective study.

† A cohort study may be a prospective study, but a prospective study is not necessarily a cohort study : a cohort study involves a methodology, i.e. comparison, that is not necessarily common to all prospective studies. The qualifier “prospective,” without further details, indicates only the study’s temporal direction.