A researcher uses the personnel records of a large insurance company to identify all employees who developed diabetes between 2010 and 2020, then selects for each diabetic employee two colleagues without diabetes who were working at the same company at the time the diabetes was diagnosed. Exposure to night shift work is then compared between the groups using pre-existing employment records. Which study design is this?
- A Retrospective cohort study
- B Case-cohort study
- C Nested case-control study ✓
- D Case-crossover study
Correct answer: C. Nested case-control study
Explanation
A nested case-control study is a case-control study conducted within an identified cohort, with controls selected from the risk set of cohort members still under observation when each case is diagnosed. This preserves the advantages of a prospective cohort while costing far less than analysing the whole cohort. A retrospective cohort would follow the entire exposed and unexposed cohorts rather than sampling controls.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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