Temporality
Bradford Hill Criteria 1995
- First the cause then the disease
- Establish a causal relationship
Strength of Association
Bradford Hill Criteria 1995
- Statistically significant
- Stronger the association, more likely to be causal in absence of known biases (selection, information, and confounding)
Consistency of Association
Bradford Hill Criteria 1995
- Replication of findings by different investigations, at different places, at different times, with different methods
Biological Gradients
Bradford Hill Criteria 1995
- Dose-response
- Incremental change in disease rates in conjunction with corresponding changes in exposure
- As exposure increases, death rates also increase
Biological Plausibility of Association
Bradford Hill Criteria 1995
- Does the association make sense biologically?
Specificity of Association
Bradford Hill Criteria 1995
- A cause leads to a single effect, however a single cause often leads to multiple effects
Reversibility
Bradford Hill Criteria 1995
- Under controlled conditions changing the exposure causes a change in the outcome
- Multiple causes for a disease outcome - 1:1 relationship between causes and outcomes
Sufficient cause
A factor that will inevitable produce the specific disease
Necessary cause
A factor that must be present if a specific disease is to occur
Component cause
A factor that contributes towards disease causation but is not sufficient to cause the disease on its own
Population based Health Action
Focuses on the whole population but reducing the health risk or improve the outcome of all individuals
Advantages of a Population bases Health Action
- Addresses underlying causes - Radical
- Large potential benefit of the whole population
- Shifts social norms
- Behaviourally appropriate
Disadvantages of a Population bases Health Action
- Small benefit to individuals - Prevention Paradox
- Poor motivation of individuals who’s population is exposed to the downside of the strategy (benefit to risk less favourable)
High Risk Health Action
- Focuses on individuals perceived to be of high risk and has targeted interventions for them to move them to the norm of the population
- a large number of people at a small risk may give rise to more cases of disease than the small number who are at a high risk
Advantages of a High Risk Health Action
- Individual motivation
- Cost effective use of resources
- Favourable benefit to risk ratio
Disadvantages of a High Risk Health Action
- Cost of screening
- Need to identify at risk individuals
- Temporary effect/ongoing process
- Behaviourally inappropriate - not changing social norms
Prerequisites for health
- Peace and safety from violence
- Shelter
- Education
- Food
- Income and economic support
- Stable ecosystem and sustainable resources
- Social justice
3 Basic Strategies
Ottawa Charter
- Enable
- Advocate
- Mediate
Enable
Ottawa Charter
Provide opportunities for all individuals to make healthy choices through access to information, life skills, and supportive environments
Individual level
Advocate
Ottawa Charter
Create favourable political, economic, social, cultural and physical environments buy promoting/advocating for health
Systems level
Mediate
Ottawa Charter
Facilitate/bring together individuals, groups, and parties with opposing interest to work together/come to a compromise for the promotion of health
Systems and individual levels
5 Priority Action Areas
Ottawa Charter
- Develop personal skills
- Strengthen community action
- Create supportive environments
- reorient health services toward primary health care
- Build healthy public policy
Primary Disease Prevention
Limiting incidence of disease by controlling specific causes and risk factors
e.g. immunisation
Secondary Disease Prevention
Reduce the more serious consequences of the disease
e.g. screening for cancers
