Association vs causation

Question 1

what is a cause?

Answer 1

An event, condition or characteristic that **preceded the disease event **and without which the disease event either would not have occurred at all or would not have occurred until some other time.”

If there is a truly causal relationship “interventions” targeted towards an outcome reduces its incidence. e.g. if there is causal relationship between physical activity and colon cancer interventions to promote physical activity will reduce the incidence of colon cancer; if there is no causal relationship there will be no effect on the incidence rate of colon cancer.

Question 2

Framework for causal inference

Answer 2

Bradford hill criteria
sufficient cause model
DAGS
Triangulation

Question 3

koch’s postulate of causual inference

Answer 3

The microorganism must be identified in all individuals affected by the disease, but not in healthy individuals.
2.
The microorganism can be isolated from the diseased individual and grown in culture.
3.
When introduced into a healthy individual, the cultured microorganism should cause disease.
4.
The microorganism must then be re-isolated from the experimental host, andfound to be identical to the original microorganism.

Question 4

Bradford hill criteria for causal inference

Answer 4

9 NOT A CRITERIA ONLY SUGGESTIONS/VIEW POINT
1. temporality (cause precedes the outcome)
2. Biologic plausibility ( plausable = probale explanation of asome biological phenomenon that caused the disease)
3.** Consistency; Repeatibility** - same results when repeated by someone else
4.** Coheerence** - makes sense given the current knowledge
5. **Analogy - comparision between two things if one exposure asbestos causes lung cancer another similar exposur carbon monofibers can also cause lung cancer
6. Biological gradient **- dose response relationship exposure increases disease risk increases
7. strenght of an association - measured with OR, RR stronger association can be causal
8. Specificity of association - one cause = one disease
9. experimental evidence If a factor is a cause of a disease, we would expect the risk of the disease to decline when exposure to the factor is reduced or eliminated.