case control studies

Question 1

what are case control studies?

Answer 1

they are observational studies - of the effect of one or more risk factors

Question 2

how do you carry out a case control study?

Answer 2

select a group of cases of a disease - essess their exposure to the risk factors of interest

also select a control group of healthy persons who are comparable otherwise with the cases

assess the exposure of the controls and calcualte odds ratio

Question 3

what are the advantages and disadvantages of case control studies?

Answer 3

advantages

• suited to rare diseases
• quick to do- no follow up needed
• odds ratio can be formed

disadvantages

• choice of controls is difficult
• can be hard to prov e that risk factor predated the disease

Question 4

how does a case control study differ from a cohort study?

Answer 4

case control - recruit both cases and controls - record risk factor retrospectively

cohort - start with disease free peoopel and record incidence of cases / risk factors as they come