4. DEFINITIONS
⢠Observational study
⢠Causation
⢠Etiology
⢠Association
⢠Necessary
⢠Sufficient
Your Assignment:
Define these terms
as they apply to
epidemiology.
5. Koch and Causation
⢠Postulates
⢠Why study association?
⢠Web of causation
⢠Do we need a better way?
6. Twelve Criteria for Causation
⢠Cause distributed at
same level
⢠Incidence much
higher in exposed
population
⢠Exposure more
frequent
⢠Disease should
follow exposure
⢠Dose dependent
⢠Expected response
⢠Association should be
the same
⢠Other cause-effect ruled
out
⢠Control results in
decreased disease
⢠Modification of host
results in decrease
⢠Human vol. always +
⢠Findings should make
sense
7. Factors in Causation of Disease
⢠Predisposing
⢠Enabling
⢠Precipitating
⢠Reinforcing
Your Assignment:
Define these terms
as they apply to
epidemiology.
9. Are Associations Always
Connected to the Disease?
NO, BUT âŚâŚâŚâŚâŚâŚâŚâŚâŚâŚ..
ďźCigarette smoking and lung cancer
ďźAge and prostate cancer
ďźCar accidents and alcohol
ďźTribal customs and kuru
ďźAgriculture and antibiotic resistance
10. Association
⢠Deals with âŚâŚâŚâŚâŚâŚ.
⢠Is concerned with âŚâŚâŚ.
⢠Is the degree of âŚâŚâŚâŚ.
⢠Has to be scientifically proven âŚ..
Your Assignment:
fill in the blanks
11. Degrees of Association
⢠No association Direct association
ďźNo possibility for association
ďźPossibly associated
ďźAssociated
ďźDirect cause and effect
12. Guidelines for Judging Whether
An Association Is Causal
⢠Temporal relationship
⢠Strength of the association
⢠Dose-response relationship
⢠Replication of the findings
⢠Biologic plausibility
⢠Consideration of alternate explanations
⢠Specificity of the association
⢠Consistency with other knowledge
13. Deriving Causal Inferences
⢠Arriving at causation from association
ďź For example, showing that Helicobacter
pylori is directly linked to peptic ulcers
14. Perspectives
⢠Causation may be limited
⢠Subject to modification
⢠Perhaps more complex than realized
⢠Sometimes not measureable
⢠âCriteriaâ are really guidelines
ďźmay be subjective