Randomisation, Blinding and Placebo

Question 1

What are the characteristics of a successful clinical trial?

Answer 1

Tailored to the patient group.
Generalisability.
Avoid unnecessary complex data requirements.
Ensure robust allocation concealment.
Ensure most appropriate choice of control arm.
Address relevant questions where genuine uncertainties exist.

Question 2

What is the timeline of a clinical trial?

Answer 2

Informed consent
Eligibility checks
Randomisation (Either Treatment A or B)
End of treatment / Withdrawal

Question 3

How can sources of bias be minimised?

Answer 3

Randomisation
Blinding
Placebo

Question 4

What are the 3 advantages of randomisation?

Answer 4

1) Balance characteristics of different groups (selection bias)
2) Avoid allocating treatment to favourable group (allocation bias: a form of selection bias)
3) Statistical comparison of the different groups will be more valid (limiting false positive error rates)

Question 5

What are methods of randomisation within fixed randomisation?

Answer 5

• Simple randomisation
• Blocked randomisation
• Stratified randomisation
• Cluster randomisation

Question 6

What is fixed randomisation?

Answer 6

Randomisation is fixed before the start of the study.

Question 7

What is simple randomisation?

Answer 7

Allocation of individuals decided randomly.

Question 8

What is block randomisation?

Answer 8

Allocation of individual in blocks of numbers. (IE: In blocks of 4 or 6 etc)

Question 9

What is stratified randomisation?

Answer 9

Stratified in blocks according to cofounding factors.

Question 10

What is cluster randomisation?

Answer 10

Participants are grouped into clusters and the whole group is randomised.
Useful in primary care and public health research

Question 11

What is adaptive randomisation?

Answer 11

Adjusting randomisation as the trial progresses to ensure good spread of certain characteristics.

Question 12

What are the different types of blinding involved in an investigative situation?

Answer 12

Single blind (patient or accessor blind).
Double blind (patient and investigator blind).
Triple blind (Patient / investigator and accessor blind). 
Open (NO blinding).

Question 13

How does blinding occur?

Answer 13

Active treatment vs Placebo.

placebo has to be identical to the active treatment.

Question 14

Where is it impossible to blind?

Answer 14

Assessors blind.

Question 15

What is a placebo?

Answer 15

Replicates the active treatment on:

• psychological effects
• performance bias
• spontaneous fluctuation in disease state.
• taste
• smell
• shape