The case-cohort design was proposed by Ross Prentice as an alternative design in epidemiologic follow-up studies that is less expensive than a full-scale cohort study. The case-cohort design involves collecting covariate data only for cases, that is, subjects who experience the event of interest in a cohort, and for members of a relatively small randomly selected subcohort. The subcohort may serve as a comparison group for several different types of disease outcomes.

The case-cohort design can substantially reduce cost and effort of exposure assessment by limiting exposure to a small fraction of the cohort with only a small loss of efficiency compared with a full cohort design. The case-cohort design is most beneficial when the most expensive part of the study is not in ascertaining subjects ...