MODULE 3 Strategies for Improving Population Health Flashcards
L1* Describe the place of individual health care in an overall framework of determinants and distribution of health of the population * Understand and apply guidelines/frameworks for assessing causation: Bradford Hill Criteria Rothman’s Causal Pies
Individual vs Population Health Care
Clinicians: individuals. treat disease to restore health. Reactive. Treating patients who are present
Population Health: health of groups of individuals, in the context of their environment. Proactive and comprehensive approach to clinical practice. Identifying and treating all appropriate patients in a population
The Public/Population Health Model
Provide maximum benefit for the largest number of people, at the same time reducing inequities in the distribution of health and wellbeing.
Epidemiology:
- Define the problem
(CSS)
- Identify the risk and protective factors
(Cohort S, Case-C S)
- Develop and test prevention strategies
(RCTs; Diagnostic Test Accuracy Studies)
- Assure widespread adoption
- Monitor and evaluate
Role of Epidemiology
To seek the cause of dis-ease, so appropriate preventative measures can be introduced.
NOT determine the cause of a dis-ease in a given individual.
Determines the relationship/association between a given exposure and dis-ease populations
James Lind’s Experiment
RCT
Prevention of Scurvy before the cause was identified
Study Participants:
12 British Sailors with Scurvy
Learned that citrus helped with treating Scurvy
Bradford Hill Criteria (1965)
“Aids to thought”
(means that not all have to be present. Judgement necessary!)
- Temporality
- Strength of Association
- Consistency of association
- Biological Gradient (dose-response)
- Biological Plausibility of association
- Specificity of association
- Reversibility
Temporality
First the cause, then the dis-ease
essential to establish a causal relation
e.g. Smoking as a cause of lung cancer: British Doctors’ Study
Strength of Association
the stronger an association, the more likely to be causal in absence of known biases (selection, information, and confounding)
BDS: RR>10
Consistency of Association
Replication of the findings by different investigators, at different times, in different places, with different methods
e.g. Multiple studies have shown similar results
Biological Gradient (dose-response)
Incremental change in disease rates in conjunction with corresponding changes in exposure
Biological plausibility of association
does this association make sense biologically?
e.g. Carcinogens in tobacco
Specificity of association
A cause leads to a single effect
However, a single cause often leads to multiple effect
e.g. Smoking –> Multiple outcomes
Reversibility
The demonstration that under controlled conditions that changing the exposure causes a change in the outcome
e.g Reduced risk after quitting in BDS
Notes on Bradford Hill Criteria
USE YOUR JUDGEMENT
Causal phenomena are usually complex- and exposure -outcome relationships are not usually 1:1.
Causal Pies Framework:
JK Rothman
A cause of disease:
An event, condition, characteristic (or combination of these factors) which play an essential role in producing the disease.
Causal Pies
- sufficient cause
- component cause
- necessary cause
Sufficient cause
Factor/s that will inevitably produce the specific dis-ease
Component cause
Factor that contributes towards disease causation, but is not sufficient to cause disease on its own
Necessary Cause
Factor (or component cause) that must be present if a specific dis-ease is to occur
Difference between Sufficient and Component Cause
Component Causes are all the possible causes. Sufficient Causes are the causes that are enough to cause an event
A CAUSAL PIE FOR TB (example)
What are the Component Cause?
What is/are the Necessary Cause?
* We use the association and several other factors to infer causation and intervene to prevent disease
* we can intervene at any number of points in the pie
* knowledge of the complete pathway is not a pre-requisite for introducing preventive measures
Component Cause:
poverty
reduced immunity
poor sanitation
overcrowding
TB Bug
Necessary Cause:
TB Bug
Why do we need to prioritise in health?
- currently not enough money to fund all health problems
- new technologies being developed everyday, incr in medical cost
Where NZ’s health dollar goes (2008)
Total budget for 2013/2014
6% public health
4% administration
26% inpatient curative and rehab care
26% outpatient/home curative and rehab
20% long term nursing
12% medical goods
6% ancillary services
Estabilishing Public Health Priorities
Problem
Solution
Decision Criteria
The problem
who is affected?
how common is it?
size, groups, seriousness
(death rates: cancer (high priority area as first but may not be this list, depending on who you are/where you are looking at))
consider death rates in diff population groups
trends over time of major risk factors in NZ
how serious is it?
The problem–how serious is it?
- age at death and premature mortality (years of potential life lost to death (YLL))
- time lived with disability (disability adjusted life years (DALY))
- population attributable risk (PAR)
risk difference= attributable reisk (AR)
=
EGO-CGO
i.e.
The amount of “extra” disease attributable to a particular
risk factor in the
exposed group
~
incidence in exposed population (EGO)
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 we removed
that particular risk factor from the
population
(WHOLE POPULATION, NOT JUST THE WHOLE GROUP)
Population Attributable
Risk (PAR)
=
Incidence in the total population –
Incidence in unexposed pop (CGO)
(PGO-CGO)
(total who got disease/total population - comparison group who got the disease/ comparison group total)
Population Attributable
Risk (PAR)
= RD x Prevalence of exposure
in the population
= risk difference (EG-CG) x (exposure group/ population)
Population Attributable Risk (PAR)
The amount of “extra” disease attributable to a particular risk factor in a particular population
Solution- effectiveness
(Second stage, after Problem)
Estimated effectiveness of the solution
How well can the problem be solved?
How well can the problem be solved?
(in terms of a particular intervention)
- target population
- expected number in population who will be reached
- evidence of effectiveness (based on known success rates in literature)
- cost
Possible ways to intervene to solve the problem
(e.g. obesity)
Brief GP intervention
National mass media campaign
school-based intervention
Decision Criteria
(after Problem and Solution)
Economic feasibility
Acceptability
Equity
Others
Economic feasibility
does it make economic sense to address the problem?
are there economic consequences if not carried out?
Opportunity cost
the health benefits that could have been achieved had the money been spent on the next best alternative invervention or healthcare programme (Tobacco use versus Obesity)
Acceptability
Will the community and/or target population accept the problem being addressed?
competing interests
Equity
does the problem disproportionately affect population sub groups?
treaty of waitangi
Legality
do current laws allow the problem to be addressed?
After Problem, Solution, Decision Criteria have been addressed…
DESICION MAKING!
Opportunity cost
foregone benefit to other patients if the same resources were invested in the best alternative way
Promotion, Prevention, Protection: Approaches to Taking Action
- Discuss the advantages and disadvantages of the
high
risk and population approaches
to prevention - Gain familiarity with the strands of the
Ottawa Charter
- a
framework for health promotion - Describe and differentiate the three different
levels of
disease prevention - Understand and be able to discuss the differences in approaches and the overlaps between:
health promotion, disease prevention and health protection - Describe the main components of the tobacco control programme in relation to health promotion, disease
prevention and health protection
Importance of preventing disease
Epidemiology can play a central role in preventing diseases by:
unravelling the causal pathway
directing preventive action
evaluation of effectiveness
the need for prevention is growing as the limitations in curing disease become apparent and as the cost of medical care escalate
Population Health Actions
- Health promotion
- Disease prevention
- Health protection
Strategies for Prevention
Population based (mass) strategy
High risk individual strategy
Population based (mass) strategy
focuses on the whole population
aims to reduce health risks of the entire population
useful for a common disease or widespread cause
e.g. immunisation, programmes, water fluoridation, legislated use of seatbelts
High Risk Strategy
Focuses on individuals perceived to be a high risk e.g. intravenous drug users, those with systolic BP > 160mmHg
intervention is well matched to individuals and their concerns e.g. screening for elevated BP then treating (e.g. intervention targeting obese adults)
(e.g. needle exchange programme–successful at preventing spread of HIV amongst IDUs)
Advantages of Population (Mass) Strategy
- radical- addressses underlying causes
- large potential benefit for whole population
- behaviourally appropriate
Disadvantages of Population (mass) strategy
- Small benefit to individuals
- poor motivation of individuals
- whole population is exposed to downside of strategy (less favourable benefit-to-risk ratio)
Advantages of High-risk individual strategy
- Appropriate to individuals
- individual motivation
- cost effective use of resources
- favourable benefit-to-risk raito
Disadvantages of high-risk individual strategy
- cost of screening, need to identify individuals
- temporary effect
- limited potential
- behaviourally inappropriate
Health Promotion
acts on determinants of wellbeing
health/wellbeing focus
enables/empowers people to increase control over, and improve their health
involves whole population in every day contexts
Alma Ata 1978
Declaration for primary health care (international conference on primary health care in Kazakhstan)
Aims of Alma Ata
protect and promote health of all
advocated a health promotion approach to primary care
prerequisites for health
- peace and safety from violence
- shelter
- education
- food
- income and economic support
- stable ecosystem and sutainable resources
- social justice
Ottawa Charter for Health promotion
“Mobilise action for community development”
Charter acknowledges that health is:
- a fundamental right for everybody
- requires both individual and collective responsibility
- opportunity to have a good health should be equally available
- good health is an essential element of social and economic development
Ottawa Charter 1986
Three basic strategies
Enable
Moderate
Advocate
Ottawa Charter
5 priority action areas
develop personal skills
strengthen community action
create supportive environments
reorient health services towards primary health care
build healthy public policy
Enable
to enable all people to achieve their fullest health potential through supportive environments, access to info, life skills, opportunities for healthy choices etc
Moderate
to bring together all parties with opposing/other interests to work towards the promotion of health
Advocate
to encourage/speak for positive changes by explaining the benefits of change
Care Pyramid
Tertiary
Secondary
Tertiary
Ottawa charter hung in the Rainbow Frame
Ottawa Charter examples
Disease prevention
disease focus
looks at particular diseases (or injuries) and ways of preventing them e.g. the incidence, the prevalence, risk factors, or impacts
Natural history of diesease prevention and strategies
Primary
limit the incidence of disease by controlling specific causes and factors
Examples :
- Immunisation
- Slip, slop, slap
- Seat belt regulations
Secondary
Reduce the more serious consequences of disease
Examples :
- Screening people 65+
for risk of hip fractures
- Rescue services for
prevention of drowning
Tertiary
Reduce the progress of complications of established disease
Examples :
- Counselling services
for people with post
traumatic stress
disorder(PTSD)
- Rehab services for
stroke patients
Health Protection
predominantly environmental hazard focus
risk/hazard assessment
(environmental epidemiology; safe water and air, bioscecurity)
monitoring
(biomarkers of exposure hazardous substances)
risk communication
(relating environmental risks to the public )
occupational health
(safety regulations on work sites)
Summary for disease prevention, health promotion and disease protection
Public Health Actions for Prevention
