Causality Flashcards
Describe an ‘epidemiological approach’
Only look at the start and end steps of a study
What are the 3 Henle-Kochs Postulates?
A cause must be necessary, specific and sufficient
What is a ‘cause’ with relation to a disease?
An exposure or factor that increases the probability of getting a disease
List 3 reasons why a link may not be causal
Bias
Confounding factors
Chance
Bradford Hill Criteria for Causality:
Describe ‘strength of association’
A causal link is more likely with a strong association
Bradford Hill Criteria for Causality:
Describe ‘specificity of association’
A causal link is more likely when an outcome is associated with a specific factor
Bradford Hill Criteria for Causality:
Describe ‘consistancy of association’
A causal link is more likely if the observation is observed in different studies and different sub-groups of a study
Bradford Hill Criteria for Causality:
Describe ‘temporal sequence’
A causal link is only likely if exposure to the expected exposure precedes the outcome
Bradford Hill Criteria for Causality:
Describe ‘dose responce’
A causal link is more likely if different levels of exposure to the believed factor leads to different risks of acquiring the outcome
Bradford Hill Criteria for Causality:
Describe ‘reversibility’
A causal link is very likely if removal or prevention of the believed factor leads to a reduced or non-existent risk of acquiring the outcome
Bradford Hill Criteria for Causality:
Describe ‘coherence of theory’
A causal link is more likely if the observed association conforms with current knowledge
Bradford Hill Criteria for Causality:
Describe ‘biological plausibility’
A causal link is more likely if a biologically plausible mechanism is likely or demonstrated
Bradford Hill Criteria for Causality:
Describe ‘analogy’
A causal link is more likely if an analogy exists with other diseases, species or settings
Describe a ‘reductionist approach’
Breakdown each step of a study from start to end
