Within an established occupational cohort of 10,000 workers followed for cancer incidence, researchers want to test whether pre-employment blood levels of a chemical predict lymphoma. They identify all incident lymphoma cases and sample matched controls from workers still at risk at the time each case was diagnosed, then assay stored serum samples only for these selected subjects. Which design have they used?

• A Case-cohort study
• B Retrospective cohort study
• C Case-crossover study
• D Nested case-control study ✓

Explanation

A nested case-control study is conducted entirely within a defined cohort: cases arise during follow-up and controls are sampled from the risk set of cohort members free of disease at the time each case occurs. This permits expensive testing of biospecimens on a fraction of the cohort. In a case-cohort design the comparison group is a random subcohort sampled irrespective of case occurrence.

Reference: Rothman, Greenland and Lash, Modern Epidemiology, 3rd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.