Lecture 21: Randomised Controlled trials

Question 1

What is a randomised control trial?

Answer 1

Randomly assigning exposure status (treatment/placebo), then find out outcome(s)

Some receive treatment while the other half (control) receives a placebo

Important that participants are blinded to their allocation

Question 2

What can be calculated from a randomised control trial?

Answer 2

Can calculate incidence
So can directly calculate relative risk and risk difference

Question 3

Is random selection = randomisation/random allocation?

Answer 3

NO
Random selection is randomly chosen participants from a larger population

Randomisation is the random allocation of the sample into the treatment arm or placebo arm

Successful randomisation means confounding is an unlikely reason for differences in outcomes between groups

Question 4

What are the advantages and limitations of a randomised control trial?

Answer 4

Advantages:
Best way to evaluate an intervention
Can calculate incidence

Disadvantages:
Need to have clinical equipoise -Genuine uncertainty about benefit or harm of intervention

Non-adherence - Participants don’t do what they’re supposed to. Can include doing what the other group is doing

Loss to follow-up

Resource intensive

Exposure needs to be modifiable (Highly selective) - Often a very select group of people included. Can affect generalisability to the larger population