An investigator wants to study whether serum biomarkers measured years ago predict future lymphoma. He uses stored blood samples from a large occupational cohort already under follow-up, selects all incident lymphoma cases that arise, and samples a subset of cancer-free members of the same cohort as controls. Which design is this?
- A Nested case-control study ✓
- B Retrospective cohort study
- C Case-cohort study
- D Prospective cohort study
Correct answer: A. Nested case-control study
Explanation
In a nested case-control study, both cases and controls are sampled from inside a defined cohort, allowing expensive assays on stored specimens at case-control cost while retaining the temporal security of a cohort. The key distractor is B: in a full retrospective cohort the entire exposed and unexposed cohorts are followed and analysed, not a sampled control subset.
Reference: Gordis Epidemiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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