Prospective OR Retrospective Cohort Study?

Esteemed Experts

For the following study design; Should this be considered as (Retrospective - Prospective) OR Retrospective Cohort Study.

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I would not be concerned about terminology as long as study methodology explained well!

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I sometimes tell students that one of the key utilities in labelling a study design is a shortcut for thinking of the common sources of bias that impact that design. As Saad noted above, you still need to describe your methodology in detail.

In this sense, taking this as a cohort study tells us that exposure/treatment is (a) measured/recorded prior to observation of outcomes (or should be!) and (b) non-randomised, therefore subject to confounding when comparing groups.

The temporal aspect here (the “retrospective” label, which is what I would typically use here) tells us that we’re dealing with pre-existing data for exposure/treatment status. As such we are limited in terms of (a) data availability and/or definitions for the exposure/treatment status and (b) the availability of confounders measured at time zero and the manner in which those confounders were measured/recorded.

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