Lecture 29: Association and Confounding

Question 1

What is an association?

Answer 1

Does the exposure increase or decrease the likelihood of the outcome?

Question 2

Outcomes can have multiple _______

Answer 2

causes

Question 3

Define a cause

Answer 3

an event, condition or characteristic [or a combination of these factors] that plays an essential role in producing an occurrence of the disease

Question 4

As per the causal pie model, many different exposures are sufficient to cause the

Answer 4

outcome

Question 5

In the causal pie model, we call the whole pie a ______ _______ of the outcome

Answer 5

sufficient cause (SC)

Question 6

In the causal pie model, each exposure is a ______ of the sufficient cause and therefore we call each of the exposures a

Answer 6

component

component cause

Question 7

Give an example of a component of lung cancer?

Answer 7

smoking is one component of a sufficient cause for lung cancer

Question 8

How can we prevent disease by eliminating exposures?

Answer 8

If we eliminate exposures, then the sufficient causes that the exposures are part of can therefore not causes the disease

Question 9

What is a necessary cause?

Answer 9

A component cause which is necessary for the disease to occur and so must be part of every sufficient cause

Question 10

What makes a valid association?

Answer 10

If the outcome is unlikely to be due to chance, bias or confounding

Question 11

The presence of a valid statistical _______ in no way implies _______

Answer 11

association

causality

Question 12

How can we determine causality?

Answer 12

We need to consider a series of guidelines and then make a judgement based on the totality of the evidence

Question 13

What is the acronym to remember the 7 guidelines to causality?

Answer 13

BEST CDS

Question 14

What are the 7 guidelines to causality?

Answer 14

Biological plausibility
Experimental evidence 
Specificity 
Temporal sequence
Consistency
Dose-responsive relationship
Strength of association

Question 15

What is meant by biological plausibility?

Answer 15

Is there a plausible biological mechanism for the association?

Question 16

What is meant by experimental evidence?

Answer 16

Is there evidence from human RCTs or animal experiments

Question 17

What is meant by specificity?

Answer 17

is the exposure specifically associated with a particular outcome but not others?

Question 18

What is meant by temporal sequencing?

Answer 18

Do we know whether it was the outcome or exposure that came first?

Question 19

What is meant by consistency?

Answer 19

are the findings consistent with findings from other studies

Question 20

What is meant by dose-response relationship?

Answer 20

Does the risk of the outcome change with increasing or decreasing amounts of exposure?

Question 21

When do does-response relationships not apply?

Answer 21

is the relationship is not linear or if you are looking at binary (smoking or not smoking) instead of levels of exposure (number of cigarettes)

Question 22

What is meant by the strength of the association?

Answer 22

The stronger the association, the less likely it is to be due to confounding or bias