PASS Cohort Study

Question 1

What is a cohort study?

Answer 1

A group of participants is selected with/without exposure
Follow up to observe outcome

Question 2

Advantages of cohort study

Answer 2

• Demonstrates temporality of association
• Efficient when randomisation is not feasible
• Real world evidence

Question 3

What do cohort studies measure?

Answer 3

Effectiveness

Question 4

What do RCTs measure?

Answer 4

Efficacy

Question 5

Types of cohort studies

Answer 5

Prospective
Retrospective

Question 6

What is the difference between prospective and retrospective cohort studies?

Answer 6

The timings - when you start research

Prospective - exposure + event determined before data collection - research starts earlier
Retrospective - exposure and event determined after data collection - research starts later

Question 7

Disadvantages of cohort studies

Answer 7

Losses to follow up - missing data
Large sample size needed for rare event or conditions that take long time to develop
More prone to confounding

Question 8

Sample size needed for cohort study of rare event

Answer 8

Large sample size

Question 9

How is a cohort study conducted?

Answer 9

Select a cohort then observe exposure + event

Question 10

What does RCT stand for?

Answer 10

Randomised controlled trial

Question 11

How is a RCT conducted?

Answer 11

Participants randomly assigned to exposure then event observed