How do we identify causes of disease?

Question 1

Define epidemiology.

Answer 1

The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control health problems.

Question 2

Define public health.

Answer 2

The science and art of preventing disease, prolonging life and promoting health through the organised efforts of society.

Question 3

What is a risk factor?

Answer 3

Any attribute, characteristic or exposure of an individual usually
associated with a higher likelihood of developing a disease or other health related outcome (but can be beneficial)

Intuitive understanding that it is something that increases our likelihood of harm

Question 4

What is an outcome?

Answer 4

The health outcome - the health-related state of interest or under study.

Question 5

What is an exposure?

Answer 5

Any factor associated with an outcome of interest.

Question 6

What could an association between an exposure and a health outcome be due to?

Answer 6

Chance
Bias
Confounding
Cause + effect

Question 7

What is the purpose of epidemiology?

Answer 7

Measure disease burden in a population
Healthcare planning and policy
Patterns/occurrence in disease
Identify causes
Evaluating interventions

Question 8

What do the Bradford Hill criteria determine?

Answer 8

Evidence of a causal relationship between a presumed cause + observed effect

Question 9

What are the 9 Bradford Hill criteria?

Answer 9

Strength of association
Consistency
Specificity
Temporality
Biological gradient
Plausibility
Coherence
Experiment
Analogy

Question 10

Explain the modified causal criteria

Answer 10

Argue against undetected bias or confounding:
Independence, consistency, specificity, strength of association

Biological evidence for a causal link:
Temporality, biological gradient, plausibility, experiment (reversibility)

Question 11

How is strength of association satisfied?

Answer 11

Larger association = more likely to be causal

Question 12

How is consistency satisfied?

Answer 12

Do multiple epidemiologic studies with a variety of locations, populations and methods show a consistent association?

Question 13

How is temporality specified?

Answer 13

Exposure must precede onset of disease

Question 14

How is biological gradient satisfied?

Answer 14

Increased exposure results in increased incidence of disease

Question 15

How is reversibility satisfied?

Answer 15

Does disease risk decline following intervention or cessation of exposure?

Question 16

How do we assess epidemiological evidence when finding causal or risk factors?

Answer 16

Weigh up weaknesses in data and alternative explanations with the quality of science and results of applying causal frameworks