Which study type uses existing records to identify a cohort at the start and follow outcomes from past data to the present or future?

Which study type uses existing records to identify a cohort at the start and follow outcomes from past data to the present or future?

• A. Prospective cohort
• B. Retrospective cohort
• C. Case-control
• D. Cross-sectional

Answer: (B)

Retrospective cohort studies use existing records to identify a defined group at the start based on past exposure, and then follow outcomes using data that already exist, up to the present or into the future. This means both the exposure status and the follow-up outcomes are drawn from historical records, without collecting new data going forward. This differs from a prospective cohort, which starts with a current or newly formed group and follows them forward in time to observe outcomes. It also differs from case-control studies, which begin with people who already have the outcome and look back to determine prior exposure, and from cross-sectional studies, which assess exposure and outcome at a single point in time without following participants over time. An example would be using medical records to identify workers exposed to a chemical in the past and then tracking disease development through subsequent records.

Retrospective cohort studies use existing records to identify a defined group at the start based on past exposure, and then follow outcomes using data that already exist, up to the present or into the future. This means both the exposure status and the follow-up outcomes are drawn from historical records, without collecting new data going forward.

This differs from a prospective cohort, which starts with a current or newly formed group and follows them forward in time to observe outcomes. It also differs from case-control studies, which begin with people who already have the outcome and look back to determine prior exposure, and from cross-sectional studies, which assess exposure and outcome at a single point in time without following participants over time. An example would be using medical records to identify workers exposed to a chemical in the past and then tracking disease development through subsequent records.