Cohort studies

Question 1

What is a cohort studies

Answer 1

We are investigating whether an exposure leads to a particular pre-specified endpoint. Can be retrospective or prospective.

Question 2

Disadvantages of prospective cohort studies

Answer 2

Relying on regular follow-ups over a long period of time
The outcome may happen after the trial - how do you specify exactly when to end the trial
Expensive
Can’t control for confounding factors

Question 3

Disadvantages of retrospective cohort studies

Answer 3

Relies on people’s memories
Can’t control for confounding variables

Question 4

Advantages of retrospective cohort studies

Answer 4

Large sample size
Cheap
Easy to obtain data
Allows us to try to find a causative link between an exposure and an outcome

Question 5

Advantages of prospective cohort studies

Answer 5

Able to control data collection and follow0up methods
and measure all variables of interest

Can measure multiple pre-defined outcomes
Good study for identifying AETIOLOGY of a disease

Can calculate relative risk

Question 6

What is relative risk

Answer 6

Risk in exposed group divided by risk in unexposed group

RR = 1 = no association
RR > 1 = positive association between risk and outcome
RR < 1 = negative association between risk and outcome