Bradford Hill Flashcards
What are the 9 factors
strength consistency specificity temporal dose-response plausibility coherence experimental evidence analogy
Describe strength
Measured by magnitude of relative risk
Stronger association more likely to be causal
Describe consistency
similar results in different populations using different study designs - more likely to be causal
Describe specificity
if exposure increases risk of certain diseases but not others - more likely to be causal e.g. mesothelioma
Describe temporal relationship
For a putative risk factor to be a cause of a disease it has to precede the disease
Easier to establish from cohort studies
Rather difficult from X-sectional or case-control
Describe dose-response
If increasing levels of exposure lead to increase risk of disease - more likely to be causal
Describe plausibility
More likely to be causal if consistent with other knowledge e.g. animal experiments, biological mechanisms etc.
Describe coherence
Does not conflict with what is already known
Why may experimental evidence be unreliable
Human experiments are rare and animal research is on a different species + different exposure levels
