A researcher identifies 5,000 women enrolled in an ongoing cohort study of oral contraceptives and breast cancer. From within this cohort, she selects all women who develop breast cancer during follow-up and samples a comparison group of women without breast cancer from the same cohort, then compares past contraceptive use. Which study design has she used?
- A Case-cohort study
- B Nested case-control study ✓
- C Retrospective cohort study
- D Case-crossover study
Correct answer: B. Nested case-control study
Explanation
When cases and controls are selected entirely from within a pre-existing defined cohort, the design is a nested (embedded) case-control study. It retains the sampling efficiency of a case-control approach while avoiding recall bias because exposure data were collected before disease onset. A case-cohort study differs because controls are sampled from the full cohort at baseline regardless of future disease status and can serve as controls for multiple outcomes.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.