Association, Causal Inference & Causality

Question 1

Cause Definition

Answer 1

Precursor event, condition or characteristics required for the occurrence of the disease or outcome

Question 2

3 Types of Associations

Answer 2

1. Artifactual (False) Associations
2. Non-causal Associations
3. Causal Associations

Question 3

Artifactual Associations

Answer 3

Can arise from Bias and/or Confounding

Question 4

Non-causal Associations

Answer 4

Can occur in 2 different ways

• Disease may cause the exposure
• The disease and the exposure are both associated with a third factor (confounding)

Question 5

Causal Associations

Answer 5

The exposure causes the outcome

Question 6

Types of Causal Relationships

Answer 6

• Sufficient Cause
• Necessary Cause
• Component Cause (Risk Factors)

Question 7

Sufficient Cause

Answer 7

• Condition or event will inevitably produce disease
• A cause that if it is present, the disease will always occur.

E.g. Some genetic abnormalities

• Can still have multiple, required components that collectively act to induce disease

Question 8

Necessary Cause

Answer 8

A cause that precedes a disease.

The cause has to occur in order for the disease to happen.

However you can be exposed to the cause without getting the disease.

Question 9

Component Cause (Risk Factor)

Answer 9

Something that, if present, increases the likelihood of a particular disease.

Can be multiple factors building on top of one another.

Question 10

Synergism

Answer 10

Two or more components that have to be present at the same time for the disease to occur.

The effect of both together is greater than the sum of the individuals

Question 11

Parallelism

Answer 11

2 or more factors that are not present at the same time. Once one or the other is there, the effect would be greater.

Either/Or

Question 12

Multiple Causation

Answer 12

Multiple component-causes working together to collectively become sufficient causes.

Question 13

Hill’s Criteria (Guidelines)

Answer 13

• Strength
• Consistency
• Temporality
• Biologic Gradient
• Plausibility

Question 14

Causal Inference Process

Answer 14

• An interpretive, application process

- The higher the number of criteria met, when evaluating an association, the more likely it may be causal.

Question 15

Strength

Answer 15

• Refers to the size of the measure of association

- The greater the association, the more likely it might be a cause.

Question 16

Consistency (Reproducibility)

Answer 16

Repeated observations of an association in different populations under different circumstances in different studies.

NOT JUST ONCE.

Can still obscure the truth

Question 17

Temporality

Answer 17

Reflects that the cause precede the effect/outcome in time.

Looks at the time between exposure and outcome

Question 18

Biologic Gradient

Answer 18

Presence of a gradient of risk associated with the degree of exposure

Question 19

Plausibility

Answer 19

Presence of a biological feasibility to the association, which can be understood and explained