Nested case control study is type of
|C||Cross sectional study|
|D||None of the above|
Since a nested case control study is a type of cohort study which begins with a population of people who are exposed or not exposed to the putative causal agent but in whom the outcome has not occurred, it is prospective in nature.
Nested Case Control studies: - it’s a type of Cohort study in which all those who develop the outcome of interest becomes the cases while those who are free becomes control. The advantage is that there is omission of confounders and the problem of recall bias is omitted out, last but not the least it is cost effective. The main determinant of the direction of study is the time when the outcome of interest occurs i.e whether the study begins with the outcome or the exposure which is thought to be causing the outcome.
Advantages of nested case control study
a. Baseline data taken initially, no problems of recalling an event- minimization of bias
b. Samples are taken a priori before occurrence of the disease- temporality of the event can be easily established ( In a traditional case control study we do not know that the events preceded the outcome or not)
c. Cost reduced- All samples need not be analyzed
A typical case control study is retrospective in nature as the outcome has already occurred at the start of the study and the history of exposure is taken in retrospect.(option B)
A cross sectional study on the other hand is carried out at one point in time, hence it is neither prospective nor retrospective in design.(option C)