Module 2 Flashcards
Individual healthcare
- Clinicians generally deal with individuals
- Aim to treat disease and restore health
- Reactive form of treatment
Population healthcare
- Health of a group of individuals in the context of their environment
- The social and physical environment of people
- Comprehensive & proactive approach to clinical practice
PHF - defintion
structure - DPIRPFDTPSAWAME
Public Health Framework: provide mass benefit for the largest number of people at the same time to reduce inequities in the distribution of health & wellbeing.
Define the problem -> Identify risk and protective factors -> Develop and test preventative strategies -> Assure widespread adoption -> Monitor and evaluate
Bradford Hill Criteria
TaBS CRaBS
Temporality Biological gradient Strength of association Consistency of association Reversibility Biological plausibility Specificity of association
Temporality
timeline will be given
- Sequence of events: Cause must precede disease.
- Essential to establish a causal relationship
e. g. Smoking -> lung cancer deaths
- Strength of association -
will mention strength
- The stronger an association, the more likely to be causal in absence of known biases (selection, information & confounding)
e. g. British doc study: RR>10
Consistency of association
- diff groups
- Replicating findings w/ different investigators, times, places, methods
e. g. Multiple studies showing similar results
Biological gradient
- Incremental change in disease rates in conjunction with corresponding changes in exposure
Biological plausibility of association
- Association making biological sense
e. g Chemicals in tobacco are known to promote cancers (carcinogens)
Specificity of association
(weakest criteria)
A cause -> single effect or effect has a single cause. But, health issues have multiple/interacting causes & many outcomes share causes.
E.g. smoking -> multiple outcomes. Multiple causes -> lung cancer
Reversibility
The demonstration that under controlled conditions changing the exposure causes a change in the outcome => likely causal relationship. e.g. reduced risk after quitting smoking
Definition of the cause of disease
event/condition/characteristic (or combination) which play an essential role in producing the disease
Causal pie - KJ Rothman
Sufficient cause, component cause and necessary cause
- Use the association and other factors to infer causation and intervene to prevent disease
- Can intervene at any number of points in the pie
- No prerequisite knowledge of the complete pathway needed to introduce preventive measures.
Sufficient cause
- The whole pie
- A minimum set of conditions without any one of which the disease would not occur
- Often several
- The disease may have several sufficient causes (several pies => same disease)
Component cause
- A factor that contributes towards dis-ease causation, but not sufficient to cause dis-ease by itself
- Component causes “interact” to produce disease
Necessary cause
- A factor that must be present if a specific dis-ease is to occur
Pop based (mass) strategy purpose
- Focuses on the whole pop & aims to reduce health risks/ improve outcomes of pop. useful for a common disease or widespread cause
- e.g.: Immunisation programmes, legislation of seatbelts, low salt foods at supermarkets
Pop based (mass) strategy advantages
- Radical - addresses underlying causes
- Large potential benefit for whole population
- Behaviourally appropriate (change societal norms)
Pop based (mass) strategy disadvantages
- Small benefit to individuals
- Poor motivation of individuals
- Whole population is exposed to downside of strategy (less favourable benefit-to-risk ratio)
High-risk individual strategy purpose
- Focuses on high risk individuals
- Well matched to individuals and their concerns
- e.g.: Intervention targeting obese adults, intravenous drug users
High-risk individual strategy advantages
- Appropriate to individuals
- Individual motivation
- Cost effective use of resources - Favourable benefit-to-risk ratio
High-risk individual strategy disadvantages
- Cost of screening, need to identify individuals
- Temporary effect
- Limited potential
- Behaviourally inappropriate (Unchanged societal norms)
Health promotion
Acts on determinants of wellbeing in pop. & enables/empowers people to increase control over/improve, their health. Usually pre-disease
Primary healthcare declaration- Alma Ata 1978
- Protect and promote health of all
- Advocated a health promotion approach to primary care
- 1st time social determinants were recognised as being key to good health for individuals in a pop
Prerequisites for health
Peace and safety from violence, Shelter, Education, Food, Income and economic support, Stable ecosystem and sustainable resources, Social justice and equity
Ottawa charter aim
Aim to mobilise action for community development.
Ottawa charter acknowledgement
health is:
- A fundamental right for everybody (human rights in health)
- Requires both individual and collective responsibility (includes government)
- Opportunity to have good health should be equally available (equity lens). Government has to focus on the prerequisites of health. Incorporate health into the policies.
- Good health is an essential element of social and economic development
Ottawa charter basic strategies
Enable, Advocate, Mediate
Ottawa charter Enable
(Individual level strategy) To provide opportunities for all individuals to make healthy choices through access to information, life skills and supportive environments
Ottawa charter Advocate
(System-level strategy) To create favourable political/economic/social/cultural/ physical environments by promoting/advocating for health & focusing on achieving equity
Ottawa charter Mediate
(Individual, group & system strategy) To facilitate/ bring together individuals/groups/ parties with opposing interests to work together/come to a compromise for the promotion of health
Ottawa charter strands
Develop personal skills
Strengthen community action
Create supportive environments
Reorient health services towards primary health care
Build healthy public policy
Ottawa charter - Develop personal skills
Increases the options available to people to exercise more control over their own health and make choices
conducive to health (through individual empowerment, providing information and education for health, and enhancing life skills)
Ottawa charter - Strengthen community action
Community empowerment: ownership and control of their own endeavours and destinies and their ability
to prioritize health interventions & issues relevant to them.
Ottawa charter - Create supportive environments
Develop the built environment to promote healthy lifestyles, and conserve natural resources.
Ottawa charter - Reorientate health services towards primary health care
Healthcare must be responsive to needs of patients and families (their culture, aspirations, capacities, resources & social norms). Includes a health promotion angle as well as being curative. Requires strong attention to health research.
Ottawa charter - Build healthy public policy
Placing health in the agenda of policymakers in all sectors- policy must reflect the changing needs of
communities and individuals. Coordinated action to create policies that foster equity.
Ottawa charter issues
- Based on Western models, universal formula (one size fits all)
- Often simply adapted for Māori, doesn’t incorporate Māori values and realities. Tended to benefit non-Māori to a greater extent than Māori
- Superficial vs structural approach
Te Pae Mahutonga
Based on the Southern Cross as a navigational aid. Fundamental components of health promotion from a Māori world view – “but as they might also apply to other New Zealanders”
Te Pae Mahutonga - Prerequisites
Ngā Manukura and Te Mana Whakahaere
Te Pae Mahutonga - Key tasks
Mauriora, Toiora, Waiora, Te Oranga
Ngā Manukura
(leadership) Health professional & community leadership. Enabling/empowering communities to do things for themselves
Te Mana Whakahaere
(autonomy): Capacity for self governance (make decisions for themselves). Community control & enabling political environment
Mauriora
Access to Te Ao Māori. “Maori world” Cultural identity, language, customs, marae.
Toiora
Environmental protection. Physical enviro are key determinants to health. Bad air/water => unhealthy
Waiora
Healthy lifestyles. Diets, exercise, no smoking/alcohol
Te Oranga
Participation in society. “Social determinants of health”. Ensuring there is resources to practice Mauriora, Toiora & Waiora. Education, income, good housing. Broader implications: Political, participation individually/collectively in political processes/decisions.
Te Pae Mahutonga Principles
- By Māori for Māori (for everyone)
- Self determination and control
- Valid models, frameworks, concepts
- Māori people, values, collectives
- Contemporary tools and methods
- Allows for diverse realities
- Focus on determinants of health
- Evidence-based
Disease prevention
Ways of preventing disease/consequences.
Primary Disease prevention
Acts before disease, aims to limit incidence
Secondary Disease prevention
Acts at early stages, aims to reduce more serious consequences
Tertiary Disease prevention
Acts after diagnosis, aims to reduce the progress of more serious consequences
Health protection
Predominantly environmental hazard focused. Risk/Hazard assessment e.g. Environmental epidemiology,
Safe air and water, biosecurity. Occupational health & Monitoring e.g. safety regulations on work sites biomarkers of exposure to hazardous substances. Risk communication: relating environmental risks to the public e.g flags at beach => drowning risk
Screening
A special type of prevention strategy
Identifying risk factors for disease/unrecognised disease by applying tests on a large scale to a population
Objective screening initiative
To improve health outcome (morbidity, mortality and/or disability)
Screening criteria
Suitable disease, Suitable test, Suitable treatment
Screening criteria: Suitable disease
- Relatively common
- Relatively uncommon: Early detection/ intervention -> better outcome
- Knowledge of the natural history of the disease (or relationship of risk factors to the condition)
- Detectable early (detectable risk factor/disease marker)
- Increased duration of pre-clinical phase
Screening criteria: Suitable test
- Reliable – provides consistent results
- Safe
- Simple
- Affordable
- Acceptable
- Accuracy: the ability of a test to indicate which individuals do/do not have the disease. 2 measures: Sensitivity & Specificity. Fixed characteristics. (Both remain the same despite where test is applied)
Screening criteria: Suitable treatment
- Evidence of early treatment leading to better outcomes
- Effective, acceptable and accessible treatment
- Evidence-based policies covering who should be offered treatment and the appropriate treatment to be offered
Screening criteria: Suitable screening programme
- Benefits must outweigh harm
- RCT evidence that screening programme will result in:
- Reduced Mortality
- Increased Survival time: Lead time bias & Length time bias
Sensitivity
Likelihood of a positive test in those with the disease.
- Increase sensitivity => increase proportion of true positives
Sensitivity = a/(a+c) = # true positives/total # with disease x100%
Specificity
Likelihood of a negative test in those without the disease.
- Increase specificity => increase proportion of true negatives
Specificity = d/(b+d) = # true negatives/total # without disease x100%
PPV
The proportion who really have the disease of all people who test positive
PPV = a/(a+b) = # true positives/# who test positive
NPV
The proportion who are actually free of the disease of all people who test negative
NPV = d/(c+d) = # true negatives/# who test negative.
If the prevalence is moderate/low means?
higher false positive test results
If the prevalence is high means?
higher false negative test results
Prioritising: Descriptive
Problem: Where are we now? Who is most/least affected? What are the trends over time? - Where have we come from? - Where are we going?
Prioritising: Explanatory
What are the determinants? What are the risks?
Why are we getting worse/better?
Why are populations different?
Prioritising: Equity
- Does the problem/risk factor disproportionately affect population sub groups? Why?
- Be mindful of obligations to the Treaty of Waitangi
Prioritising: Evaluative
What can improve health outcomes (and in whom)?
How well can the problem be solved?
- Target population
– Expected # in population who will be reached
– Evidence of effectiveness (based on known success rates)
– Cost
Prioritising: Economic feasibility
- Does it make economic sense to address the problem?
- Are there economic consequences if not carried out?
Prioritising: Opportunity cost
The health benefits that could have been achieved had the money been spent on the next best alternative intervention or healthcare programme
Prioritising: COMMUNITY EXPECTATIONS & VALUES. PUBLIC ATTITUDES. HUMAN RIGHTS & SOCIAL JUSTICE
- community expectations & values - public attitudes considered: If not considered => ineffective preventative measures
- human rights & social justice: Treaty of Waitangi
Prioritising: Acceptability
- Will the community and/or target population accept the problem being addressed?
- Competing interests
Prioritising: What do communities want?
- Confidence in the health system – Access to necessary care – Fair treatment – Culturally appropriate – Good information about their options
EPIDEMIOLOGICAL MEASURES
- Death age/premature mortality-Years of potential Life Lost (YLL)
- Time lived with disability - Years Lived with a Disability (YLD)
- Population Attributable Risk (PAR)
Attributable risk
RD = AR = EGO - CGO
- The amount of “extra” disease attributable to a particular risk factor in the exposed group
- Incidence in exposed population (EGO)
- For High risk interventions, we target the risk factor w/ greatest AR.
Population attributable risk
PAR
- The amount of “extra” disease attributable to a particular risk factor in a particular population
- If the association is causal – this is the amount of disease (theoretically) we could prevent if that particular risk factor is removed from the pop
- Pop based interventions: target the risk factor which has the greatest PAR as this will benefit the most people.
- If prevalence is high then the PAR is high
Incidence in total pop - Incidence in unexposed pop
PGO - CGO
(a+b)/P - b/CG
