Module 3 Flashcards
Define Epidemiology
Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health
problems
What does the Bradford Hill criteria show?
a group of minimal conditions necessary to provide adequate evidence of a causal relationship between an incidence and a possible consequence,
What are the seven aspects to the Bradford Hill criteria?
- Temporality
- Strength of association
- Consistency of association
- Biological gradient (dose-response)
- Biological plausibility of association
- Specificity of association
- Reversibility
Explain Temporality
The effect has to occur after the cause (and if there is an expected delay between the cause and expected effect, then the effect must occur after that delay).
Explain Strength of association
The stronger an association, the more likely to be causal in absence of known biases (selection, information, and confounding)
Explain Consistency of association
Replication of the findings by different investigators, at different times, in different places, with different methods
ie multiple studies have shown similar results
Explain Biological gradient (dose-response)
Greater exposure should generally lead to greater incidence of the effect. However, in some cases, the mere presence of the factor can trigger the effect. In other cases, an inverse proportion is observed: greater exposure leads to lower incidence
EXPLAIN Specificity of association
A cause leads to a single effect
However, a single cause often leads to multiple effect
e.g. smoking
EXPLAIN Reversibility
The demonstration that under controlled conditions changing the exposure causes a change in the outcome
define the term ‘a cause of disease’
an event, condition, characteristic (or combination of these factors) which play an essential role in producing the disease
Define ‘A Necessary cause’
is a factor (or component cause) that must be present if a specific dis-ease is to occur
A Component cause is a
factor that contributes towards dis-ease causation, but is not sufficient to cause dis-ease on it’s own
A Sufficient cause is a
factor/s that will inevitably produce the specific dis-ease
Is Knowledge of the complete pathway of a dis-ease a pre-requisite for introducing preventive measures
no
What is the high risk strategy?
Focuses on individuals perceived to be a high risk
• Examples: Intervention targeting obese adults, intravenous drug users
What is the Population based (mass) strategy?
Focuses on the whole population
• Aims to reduce the health risks/ improve the outcome of all individuals in the population
• Useful for a common disease or widespread caus
What are the advantages for Population (mass) strategy?
- Radical - addresses underlying causes
- Large potential benefit for whole population
- Behaviourally appropriate e.g. smoking in airplanes (smokers get onto flight knowing that they can’t smoke)
What are the disadvantages for 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
What are the advantages forHigh risk individual strategy?
• Appropriate to individuals • Individual motivation • Cost effective use of resources • Favourable benefit-to-risk ratio
What are the disadvantages forHigh risk individual strategy?
- Cost of screening, need to identify individuals
- Temporary effect
- Limited potential - might miss people not in the high risk group who still may get the disease
- Behaviourally inappropriate - since it is a relatively smaller target group, its easier to go against it since it is not the social norm.
What is Primary care?
Patients regular source of healthcare e.g. GP, pharmacist, physiotherapist Community based
What is secondary care?
Specialist care (e.g. Neurologists, dermatologist)
What is tertiary care?
hospital based care, Rehabilitation
What are the three types of health actions?
- HEALTH PROMOTION
- DISEASE PREVENTION
- HEALTH PROTECTION
Explain the Alma Ata 1978:Declaration for Primary health Care
- Protect and promote health of all
* Advocated a health promotion approach to primary care
What did the Alma Ata 1978:Declaration for Primary health Care have as their prerequisites for health?
- Peace and safety from violence
- Shelter
- Education
- Food
- Income and economic support
- Stable ecosystem and sustainable resources
- Social justice
What was the goal of the Alma Ata 1978:Declaration for Primary health Care?
‘Mobilise action for community development’
The charter acknowledges that health is:
•A fundamental right for everybody
•That it requires both individual and collective
responsibility
•The opportunity to have good health should be equally
available
•And that good health is an essential element of social
and economic development
What is in the circle of the Ottawa Charter 1986?
The three basic strategies:
Enable
Mediate
Advocate
What are the steps to the progression of disease?
Exposure
Biological onset
Clinical Diagnosis
Outcome: Recovery, Death or Disability
Where does primary prevention work on in the progression of a disease?
Limit the incidence of disease by controlling specific causes and risk factors by preventing biological onset
e.g. immunisation
Where does secondary prevention work on in the progression of a disease?
Reduce the more serious consequences of disease
before clinical diagnosis - e.g. beats cancer screening
Where does tertiary prevention work on in the progression of a disease?
Reduce the progress of complications of established disease after clinical diagnosis
e.g. rehab services
Explain Health protection
Predominantly environmental hazard focused
• Risk/Hazard assessment
• Monitoring
• Occupational health
What is another term for Risk Difference?
Attributable risk (EGO - CGO)
What is PAR? Explain it
Populatrion Attributable Risk - 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
What measuemrent is used for the high risk strategy?
For high risk individual we use Risk difference
What measuemrent is used for the population strategy?
For population strategy we use PAR
How do you calculate PAR?
Incidence in the total population (PGO) - incidence in unexposed group (CGO)
OR
RD x Prevalence of exposure in the population
Define Opportunity Cost
The health benefits that could have been achieved had the money been spent on the next best alternative intervention or healthcare programme
How does Obesity spread in gender?
Affects females first and then males, but the male obesity takes over the female obesity rates
How does obesity spread in high vs low SES?
Starts off in the high income people, and then affects the low income people.
What is the model for health promotion used by Maoris?
Te Pae Mahutonga
Before implementing any health promotion model, what are the prerequisites so that this health promotion works effectively?
BASIC human requirements like peace, shelter, education, food, income, stable eco-system, sustainable resources, social justice & equity
What are the four key tasks of Te Pae Mahutonga ?
Mauriora
Waiora
Toiora
Te Oranga
Explain Mauriora
- access to Te Ao Maori (access to the Maori world)
Explain Waiora
Environmental protection
Explain Toiora
Healthy lifestyles (eating right, drinking right, exercise etc)
Explain Te Oranga
Participation in society - having social economic resources to participate in education
And participation in the political aspect which will shape your community or environment.
What are the two prerequisites of Te Pae Mahutonga?
Nga Manukura and Te mana Whakahaere
Explain Nga Manukura
Health professional and community leadership
Explain Te mana Whakahaere
Capacity for self governance (autonomy)
And community control and enabling a political environment, i.e. choices that a community wants to make is not constrained.
Can Maori health promotions be applied to the whole population/
Yes it can and may be more affective than general ‘one size fits all’ health promotions.
Define screening in health
Screening involves identifying unrecognised
disease or risk factors for disease by applying tests on a large scale to a population
What does it mean by having an unrecognised diseases?
The individual does not know they have the disease.
Are screening programmes primary or secondary prevention strategies?
Can be both e.g. Screening women for alcohol intake to prevent breast cancer is primary prevention, while breast cancer screening is secondary since it is after biological onset.
Those who are more likely to have a disease are
test positive
What is the difference between a screening test and a diagnostic test?
Screening test is less expensive diagnostic test, while a gold standard diagnostic test is more expensive and more accurate.
Those who are disease negative and test negative will be
re-screened
Those who are test positive and disease positive will
go through intervention or treatment.
What is the screening criteria?
- Suitable disease 2. Suitable test
- Suitable treatment
- Suitable screening programme
What is the objective of a screening initiative?
To improve health outcome (morbidity, mortality and/or disability)
Does a suitable disease have to be relatively common to be screened?
no, can be relatively common or relatively uncommon!
What are the two criteria of a ‘suitable disease’?
Must be an important health problem.
Must have knowledge of the natural history of the disease (or relationship of risk factors to the condition), therefore it should be able to be detected early and increase the pre clinical phase.
What is the pre clinical phase?
Time between early features of disease and clinical diagnosis of the disease.
What is the criteria to a ‘suitable test’?
- Reliable –provides consistent results
- Safe
- Acceptable
- Simple
- Cheap
- Accuracy ‐ The ability of a test to indicate which individuals have the disease and which do not
What are true positives?
Those who have the disease and test positive
What are true negatives?
Those who don’t have the disease and are test negative
What are false negatives
Those who have the disease but get test negative
What is sensitivity and how do you calculate this?
- The ability of the test to identify correctly those who have the disease (a) from all individuals with the disease (a+c)
- The likelihood of a positive test in those with the disease
True positives/all with disease x 100
What is specificity? give an equation to calculate this
- The ability of the test to identify correctly those who do not have the disease (d) from all individuals without the disease (b+d)
- The likelihood of a negative test in those without the disease
True negatives/all without disease x 100
Difference between specificity and sensitivity
• The sensitivity of a screening test is high if the proportion of true positives is high
• The specificity is high if the proportion of
true negatives is high
Is sensitivity and specificity a fixed value of the test?
Yes
What is positive predictive values? and give a formula
- The proportion who really have the disease of all people who test positive
- The probability of having disease if the test is positive
true positive/all who test positive x 100
What is negative predictive values? and give a formula
- The proportion who are actually free of the disease of all people who test negative
- The probability of not having the disease if the test is negative
true negatives/all who are tested negative x100
Are PPV and NPV fixed characteristics of the test?
No, it depends on the test accuracy and prevalence of disease.
How do they trial a screening programme?
RCT
What is lead time bias?
if the screening programme is evaluated in terms of survival time, this may give a false impression of success
What is length time bias?
Calculating mean survival from screened patients gives an impression of longer average survival than occurs in the population, when taking average of disease with different progression rates
What are three types of ethnicity outputs
- Prioritised Output
- Total Response (Overlapping) Output
- Sole/combination Output
What does the Prioritised Output ensure?
The prioritisation is to ensure that where some need exists to assign people to asingle ethnic group, ethnic group of policy importance, or of small size, are not swamped by the NZ European ethnic group.
Explain the prioritised output system:
Each respondent is allocated to a single ethnic group using the priority system.
Where is the prioritised output system used?
Frequently used in MoH and health and disability sector for funding calculation,monitoring changes in the ethnic composition of service utilisation and so on.
Although MoH has started to include Total Outputs as one of its ethnicity outputs
these days.
What are the advantages of the prioritised output system ?
- Produces data that are easy to work with
- Sum of ethnic group population is the total NZ population
• Help to collect data on ethnic groups of policy importance, small size so that they
are not swamped by the NZ European ethnic group.
What are the disadvantages of the prioritised output system ?
• Place people in specific ethnic groups through prioritisation process may simplify
but cause biases to the resulting statistics.
- Over‐represents some groups at the expense of others. Māori PI, PI others
- Goes against principle of self‐identification
Explain the Total Response Outputs system:
Individuals who indicate more than one ethnic group arecounted more than once, the sum of the ethnic group
populations will exceed the total population of NZ.
Who uses the Total response output system
Census uses Total response output
What are the advantages of the Total response output system?
- Represents all those people who identify with any given ethnic group
- Does not change the responses that people give
What are the disadvantages of the Total response output system?
• The sum of ethnic group population “counts” will exceed the total population
of NZ
• Create difficulties in distribution of funding based on population numbers
• Create difficulties in monitoring changes in the ethnic composition of a
population.
Explain Sole/Combination Output system
9 groups (there are actually more than that)
What are the advantages of the Sole/Combination Output system?
• Does not change the responses that people give and reflects the diversity of the
population
• Actual population size
• Most flexible approach as both of the other two output forms can be derived from it.
What are the disadvantages of the Sole/Combination Output system?
• This form of output is new and relatively untried.
• Will fail to include some combinations of ethnicities
• Māori population may be misidentified as they are the most likely (ethnic group) to
record multiple ethnicities
• A table or any other means or presenting the data for the whole population can be
quite large. Managing such data presentation can be problematic in practical terms
