Meaures of Association

Question 1

What is analytical epidemiology?

Answer 1

Analytic epidemiology is when we want to find out whether an exposure is associated with an outcome
Does the exposure increase or decrease the occurrence of the outcome? If an exposure is associated with an outcome when the exposure changes it should change the outcome

Question 2

PECOT

Answer 2

P - population (group of people in study)
E - exposure (potential determinant of the outcome)
C - comparison (potential determinant is being compared to)
O - outcome (health outcome being assessed)
T - time (how long follow up period was)

Question 3

Source vs sample population

Answer 3

Source population is the group people were recruiting from
Sample population is the group included in the study (took part)

Question 4

Relative risk

Answer 4

Relative risk is the exposure/comparison - how many more time likely are the exposed group to develop outcome than the comparison group. Ratio of two incidences, cannot go below 0
When relative risk is 1 there is no associated between exposure and outcome - this is the null value

Question 5

What does it mean when there are greater incidence of outcomes in the exposed group?

Answer 5

Exposure is a risk factor for outcome when increased in incidence of occurrence in exposed group - increases risk of the outcome

Question 6

What does it mean when there are greater incidence of outcomes in the comparison group?

Answer 6

Exposure is potentially a protective factor for outcome if the incidence of the comparison group increases - protects you from developing outcome

Question 7

To interpret relative risk we should say?

Answer 7

The exposed group were value as likely to develop outcome compared to comparison group

Question 8

What is risk difference/attributable risk?

Answer 8

We take the incidence of the exposed group and minus the incidence of the comparison group which tells us how many extra/fewer cases of outcome are in the exposed group are attributable to the exposure

Question 9

What are risk factor, protective factor and null value for risk difference?

Answer 9

Null value in risk difference/attributable risk is 0, where incidence of exposure = incidence of comparison
If incidence of exposure > incidence of comparison, RD > 0, the exposure is a risk factor
If incidence of exposure < incidence of comparison, RD < 0, the comparison is a protective factor

Question 10

How do we interpret the risk difference?

Answer 10

There were value (with units) extra/fewer cases of outcome in exposed group compared to comparison group
Value different depending if you use incidence proportion and incidence rate

Question 11

Relative risk vs risk difference

Answer 11

Relative risk: provides ideas of causes of the outcome, further from null value stronger association between risk factor and outcome, measures strength of association
Risk different: measures impact of exposure on the overall case load of the outcome and impact of removing exposure in population