Phase 3 clinical trials

Question 1

What are the primary aims of a phase 3 clinical study

Answer 1

Definitive safety and efficacy study

Monitor side effects

Compare the drug to standard treatments

Question 2

What are the differences between phase 3 studies and earlier studies

Answer 2

They are big (sample size of 1000s)

They are often multinational

The duration is often for a relatively long period (up to 5 years)

Large numbers of (expensive) staff required to run the trial

Command and control and data capture are challenging

Question 3

What does “PICO” stand for in phase 3 trial design

Answer 3

Population

Intervention

Comparator

Outcome

Question 4

How is the PICO method applied in phase 3 study design

Answer 4

Population
- Balance between inclusivity and risk of demonstrating the primary end point
- If n is too large
§ Increase time and cost
§ Unethical?
- If n is too small
§ Cannot detect a significant difference
□ Statistical difference
□ Clinical difference

Intervention and comparator
- Parallel or cross-over study design

Outcome
- Demonstration of the primary end point

Question 5

What is a key advantage of cross-over study design in phase 3 clinical trials?

Answer 5

Each participant serves as their own control, reducing variability and allowing for a smaller sample size

Question 6

What is a disadvantage of cross-over study design in phase 3 clinical trials?

Answer 6

A “washout period” is needed to reduce the risk of a “carry-over” effect

Question 7

What is the relationship between sample size and statistical power in a phase 3 study?

Answer 7

If sample size is too small
- Cannot detect a significant difference
□ Statistical difference
□ Clinical difference