What is True about case control study A/E and explain in detail?
Case control study: An epidemiological study where a group of individuals with disease (CASE) are compared with a group of individuals who are not suffering from disease (CONTROLS) in terms of specific disease causing exposures. Since the staing point is a group of people who already have suffered from the disease, this is labeled as a retrospective study.(BACKWARD LOOKING STUDY) Advantages of case control studies Relatively quick and easy to undeake. Relatively cheap to undeake. Only method useful in rare diseases. Not enmeshed in problems of follow-up as the data is collected at one point in time. Can be used to study the effect of many exposure variables on a single disease outcome. Drawbacks of case control studies Prone to selection and recall bias. Can't measure relative risk or provide incidence estimates . (Only odd's ratio can be calculated from the type of study, which is a rough estimate of relative risk. But when the disease in question is a rare one odd's ratio is almost equal to relative risk.) Sometimes the occurrence of the exposure in terms of time, i.e. whether it occurred before the disease may be difficult to estimate. Can't be used for rare exposures. Attributable risk can be estimated in a coho study. Ref : Park's Textbook of Preventive and Social Medicine; 18th edition; Page-65