A researcher wants to study the association between a dietary factor and colon cancer. He selects cases and controls entirely from within an already-established prospective cohort that has stored baseline data and biological samples on all its members. Which study design is he using?

• A Case-cohort study
• B Proportional mortality study
• C Historical prospective cohort study
• D Nested case-control study ✓

Explanation

A nested case-control study samples cases and controls from within a defined cohort, with controls selected from those still at risk when each case is diagnosed. The key distractor is the case-cohort study, which also samples from a cohort but selects the control group as a random subcohort chosen at the start, independent of case occurrence, so it can be compared against multiple disease outcomes.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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