Lecture 8.1: Cohort Studies

Question 1

What is a Cohort Study?

Answer 1

• A type of longitudinal study
• An approach that follows research participants
  over a period of time (often many years)

Question 2

Advantages of Cohort Studies: They are better than Case-Control Studies at..? (3)

Answer 2

• Studying a range of different outcomes
• Studying a rare exposure
• Establishing that exposure(s) precede
  outcome(s)

Question 3

Advantages of Cohort Studies (3)

Answer 3

• The time sequence of events can be assessed
• It is possible to measure the incidence /risk of
  disease directly
• There is reduced recall and selection bias
  compared with case control studies

Question 4

Disadvantages of Cohort Studies (7)

Answer 4

• Usually large and resource intensive
• Take a long time
• Rigorous definitions of disease and exposure
  can require expensive and sometimes intensive/
  invasive investigation
• Risk of high number of losses to follow-up
• Not good for rare diseases (would get too few
  cases)
• As it takes a long time, it is difficult to maintain
  consistency of measurements and outcomes
  over time
• Individuals may modify their behaviour over time

Question 5

Case-Control Studies

Question 6

What is the criteria for picking someone for a Cohort Study? (3)

Answer 6

• Select disease-free individuals
• Classify the individuals by their exposure * Calculate incidence rates for each exposure
  group