Nested Case-Control (NCC) studies
Epidemiological cohort studies of rare diseases are usually expensive to conduct because a large number of individuals need to be followed up for a long time in order to obtain an adequate number of cases. Moreover, the cost of assembling data on exposures of interest, pre-defined risk factors and confounders for the entire cohort can be financially prohibitive.
Constructing a case-control study from a small sample of a population nested within a cohort (‘nested case control (NCC) design’) has been widely used as a cost-effective alternative to the full-cohort design and is proposed to reduce the effort required to examine the effects of exposure to medicines for safety surveillance. In the NCC study design, cases of an event occurring in a defined cohort are identified and for each, a specified number of controls are selected from those in the cohort who did not have the event. The advantage of using the NCC design within M-PEM studies is that all cases and controls derived from the same well-defined source.
Furthermore, for many research questions, the NCC design potentially offers reductions in the cost and effort of data collection and analysis compared with the full cohort approach, with relatively minor loss in statistical efficiency.
The DSRU has experience in using the nested case-control design to answer various research questions and can assist with the design and analysis of such studies.