Causality

Question 1

Associations may be present in the absence of a true cause-effect relationship. They may be:

Answer 1

• Due to systematic and random variation confounding, bias and chance
• Due to a common cause
• Reverse causality

Question 2

What is the Bradford Hill criteria?

Answer 2

It is a set of criteria for causality to evaluate the strength of evidence in favour of a cause-effect relationship

Question 3

What is the concept of causality?

Answer 3

It is understanding that multifactorial web of factors that leads to disease. It is the assessment of the likelihood or risk of disease.

Question 4

What is the hierarchy of evidence?

Answer 4

1. Systematic reviews
2. Randomised controlled trials
3. Cohort studies
4. Case-control studies
5. Cross-sectional surveys
6. Case reports

Question 5

What are the nine Bradford Hill criteria for causality?

Answer 5

1) Strength of association 2) Specificity of association 3) Consistency of association 4) Temporal sequence 5) Dose response 6) Reversibility 7) Coherence of theory 8) Biological plausibility 9) Analogy

Question 6

Explain the reversibility criteria.

Answer 6

A causal link is more likely of removal or prevention of the putative factor leads to removed or non-existent risk of acquiring the outcome

Question 7

Explain the temporal sequence criteria.

Answer 7

A causal link is more likely if the putative factor is shown to precede the outcome

Question 8

A …… is an exposure factor that increases the probability of disease

Answer 8

CAUSE