Sem 2 (4)

Question 1

Cohort study advantages

Answer 1

Better at studying range of different outcomes
Better at studying rare exposure
Better at establishing that exposure precedes outcome
Better for conditions that fluctuate with age

Question 2

Cohort study issues

Answer 2

Confounding

Chance - random error

Loss to follow up (people drop out)

Information bias

Takes a long time

Question 3

Cohort study
How do you do it?
Give an example

Answer 3

1. Group individuals according to exposure
2. Ascertain outcomes for everyone
3. Compare incidence rates

5,000 people followed up from age 55 for 10 years:
3,000 non-smokers - 20 developed lung cancer
2,000 smokers - 200 developed lung cancer

Question 4

Types of cohort studies (2)
Summarise

Answer 4

Concurrent/prospective - find unexposed and exposed and wait for outcomes to occur

Historical/retrospective - look at past exposure and see whether outcome has occured

Question 5

Model to describe a study

Answer 5

PICO

Question 6

PICO

Answer 6

Population
Intervention/exposure
Comparison/control
Outcome

Question 7

Standardised mortality ratio

Answer 7

Ratio between the observed number of deaths in a study population and the number of deaths that would be expected, based on age and sex specific rates in a standard population

Question 8

Standardised mortality rate equation

Answer 8

Observed no of cases/expected no of cases

Question 9

What else do you need to calculate when working out the standardised mortality ratio?
Give the equation

Answer 9

Error factor

E^ 2 (square root) of 1/O