Pophealth exam

Why we need to prioritise in health?

1. Because there is not enough funding to fund all health problems
2. health care is primarily funded through tax revenues
3. Funding gone to prevention and health public services is extremely low, therefore, there is a high need to prioritse where funding goes

What is PECOT

Participants - who is taking part and how many in the study

Exposure group - how many people have been exposed to the exposure factor
Note: can have more than 1 EGO but only 1 CGO

Comparison group - how many people in the study have not yet been exposed

Outcome - how many people became dis-eased and what effect did the exposure factor have

Time - was the study data collected with prevalence or incidence

what is incidence

Calculating number of onsets is dis-ease occuring during a period of time

Is determined only by disease risk (is clean measure of dis-ease occurence)

difficult to observe as it is over timed

What is prevalence

Calculating number of people with a dis-ease at a point in time

Used for dis-eases where the dis-ease onset may be easy to observe, but vary in severity e.g. asthma

Gives less information than incidence as time is not involved

(is dirty measure of dis-ease occurence)

Relatively easy to measure as you can count at snapshot of time

What is point and period prevalence?

period prevalence are Dis-ease outcomes measured at one point in time but have occurred over a previous period of time. Gives a time frame to remember.

does every study include EGO and CGO?

No

How do you calculate RR

EGO/CGO (has no units)

When EGO\=CGO, then RR is 1

Relative risk reduction (RRR) when RR

What is risk difference

EGO-CGO

When EGO\=CGO, then RD is 0

Finds difference in occurrences

Absolute risk reduction (ARR) when RD

What is the crude death rate?

Total number of deaths/total population/time

what is age standardisation?

age standardization is a method of accounting for a populations age to make it more accurate when comparing disease prevalence in two different countries with major age differences.

To calculate age standardisation, calculate crude death rate for each age group, then divide each age group by its standardised population value

What are the 3 types of random errors?

Random sampling error
- Sample population will never be representative of whole population

Random measurement
- Human error in measuring exposure factors/outcomes

Random allocation error
- EG and CG differ by chance alone

What can we use to describe random error?

confidence intervals

What is a 95% confidence interval?

There is about 95% that true value in a population lies within 95%

If interval is higher, it means less confidence because value ranges of EGO and CGO can overlap each other (becomes statistically non significant)

If EGO and CGO overlap, study can still be considered statistically significant, ONLY if RR and RD calculations DO NOT cross no effect line

What does a meta analysis do to a confidence interval?

will male CI more narrower, meaning higher confidence

What is ramboman: recruitment

Are participants representative of eligible population? Is it applicable

There are 3 levels in triangle, Setting, Eligibility and Participants

Is reduced by increasing sample size

What are allocation errors

bad allocation process - groups are not defined properly

confounding - mixing of effects. When exposure group is mixed with multiple other factors associated with the outcome

Solution for confounding -

1. divide the study into substudies to separate all EG's
2. Randomisation of groups decreases confounding

What are maintenance errors?

1. People switch between EG and CG during study
2. Exposed to confounding factors
3. Participants drop out of study

What are blind and objective measurement errors?

Are outcomes measured properly and are methods of measurement objective?

What are randomised control trials?

Investigates effects of different interventions (exposures) on dis-ease incidence on different groups of individuals

It is a longitudinal and experimental study

what are advantages of RCT

Minimises confounding

What are the disadvantages of RCT

- Has ethical problems

- High costs, large studies are expensive

- Maintenance error is high as follow up period is long term
Random errors are high

what is a cohort study

Investigates whether A leads to B
Associations between risk factors (exposures) and dis-ease incidence in diff groups of individuals / looks at effects

is longitudinal and observational

adv of cohort studies

- Cheaper to conduct

- Avoids recall bias (when asking participants to recall information about exposure, may not remember exact values or may over/underreport) as exposure measurement is done prior to outcome measurement

-Provides clear time sequence between exposure and dis-ease outcomes

drawbacks of cohort

confounding is common

maintenance error is common because exposure is not controlled by investigators

What is a cross sectional study

Measures dis-ease prevalence in defined groups of individuals and differences in groups
Investigated associations between risk factors and dis-ease prevalence in groups

is cross sectional and observational

adv of cross sectional study

:
Cheap
Quick
No maintenance error

disadv of cross sectional

Reverse causality (unclear time sequence - did exposure cause the cause or vice versa)

Confounding (allocation error) is common

Limits interpretation of cause and effect

Recruitment error can be high

Recall bias (allocation error) when asking participants to recall information about exposure, may not remember exact values or may over/underreport)

what is an ecological study

Investigates associations between exposures and dis-ease prevalence OR incidence
Investigates trends and causes of dis-ease incidence and prevalence

longitudinal or CS
experimental or observational

adv of ecological study

Useful for rare diseases

Cheaper and quicker than other studies because it uses data already collected

disadv of ecological study

Confounding (allocation error) is VERY common because it is measurement between groups

what are downstream determinants of health

operates at proximal (micro) level (deal as it comes)

what are upstream determinants of health

operates at distal level (harder to change)

What are the 3 main sections of the Dahgren and Whitehead model

Individual - age, sex, biology, behaviour risk factors and lifestyle

Community - home, workplace, education, local influences

Environment - General socioeconomic, cultural and environmental conditions & Living and working conditions

In the rainbow mode, which level are non modifiable?

Age, sex and constitutional factors

What is agency

the ability of a person to act independent and make choices

What is structure

physical, social and environmental factors which affect opportunities and options which people have

What are factors of the public health framework?

looks at max benefit for max number of people, while minimising inequities

1. Define the problem - Cross sectional studies

2. Identify risk and protective factors - Cohort / case-control studies

3. Develop and test prevention strategies - Randomised control trials

4. Assure widespread adoption

5. Monitor and evaluate

What did Lind's experiment find?

Gave sailors different treatments for scurvy and found that vitamin C helped

What is the bradford Hill framework

Looks at causality

Not used as much anymore because we know that many things can cause a single result

What does the bradford hill framework consist of?

Temporality

Strength of association (most prioritised)

consistency of association

biological gradient

biological plausibility

specificity (least prioritised)

reversibility

What is temporality

Cause before disease (timeline)- therefore issue in cross-sectional study

What is strength of association

More likely to be causal if association is strong

What is consistency of association

Different studies show the same findings

What is the biological gradient

Increasing exposure \= increasing rate of disease

What is biological plausibility

The association or causal relationship can be explained in a biological sense.

What is specificity

One cause leads to ONE single result.

What is reversibility

Changing the exposure will result in a change in outcome

What are components of the causal pie

1. Sufficient cause - entire pie (all factors which are sufficient enough to produce an event)

2. Component cause - one section of pie (a factor which contributes as a component towards causing disease
Removal of one component cause can prevent disease

3. Necessary cause - must be present for event to happen

What is health promotion

Focuses on determinants of wellbeing (health focused rather than disease focused)

What is disease prevention

Focuses on a particular disease and how we can prevent it (disease focused)

What is the Ottawa charter

Health was stressed as a fundamental right for everyone
Requires both individual and collective responsibility
Good health is essential for social and economic development

what is enabling in the ottawa charter

Provide opportunities for all individuals to make healthy choices through access to information, life skills and supportive environments.

what is advocating in the ottawa charter

To create favourable environments and focusing on achieving equity in health

what is mediating in the ottawa charter

To facilitate and bring together groups with opposing interests to compromise and work together for health promotion

What was the Alma Ata 1978

was a declaration for primary healthcare
Protect and promote health for all
Advocated a health promotion approach to primary care

What is Te Pae Mahutonga?

Mauriora
Waiora
Toira
Te Oranga

2 prerequisites
Nga Manukura
Te Mana Whakahaere

what is the primary stage of disease prevention

Limits the disease by controlling specific causes and risk factors before biological onset of the disease

what is the secondary stage of disease prevention

reduces the more serious consequences of disease

what is the teritary stage of disease prevention

Reduces the progress of complications of the established disease

what is sensitivity

the likelihood of a positive test in those who have the disease
It is the ability of the test to identify those who actually have the disease from all who have the disease

How do you calculate sensitivity?

(True positive/all with disease)*100

what is specificty

likelihood of a negative test in those without the disease
The ability of the test to identify correctly those who do not have the disease from all who do not have the disease

how do you calculate specificity

(True negative/all without the disease)*100

What is the positive predictive value (PPV)

Proportion who really have the disease of all people who test positive

(True positive/all who test positive)*100

What is negative predictive value (NPV)

Proportion who are actually free from the disease of all people who test negative

(True negative/all who test negative)*100

what is lead time bias

apparent increase in survival time due to earlier screening of disease

What is length time bias

apparent increase in average survival time for a disease that has varying speeds of progression

What does health protection focus on?

Focuses on environmental hazards

What is the population based mass strategy

Focuses on whole population -
addresses risk factors
Improves health outcomes of everyone

Useful for common disease or widespread cause (e.g. low salt at supermarkets)

what are advantages of a population based strategy?

Addresses underlying cause

Large benefit for whole population

Behaviourally appropriate

what are disadvantages of population based mass strategy

Small benefits to individuals

Poor motivation of individuals as not always personally applicable

High risk (individual) strategy

Focuses on individuals perceived as high risk

Intervention is usually well tailored to individual and their particular concerns

What are adv of high risk individual strategy

Appropriate to individuals

Individual motivation

Cost effective use of resources

disadv of individual based high risk strategy

Cost of screening and identifying individuals can be high

Does not address underlying problem

Behaviourally inappropriate

3 factors for establishing population health priorities

Evidence based measures

community expectations and values

human rights and social justice

What is population attributal risk (PAR)

Is the amount of extra disease attributal to a particular risk factor in a POPULATION

Rate will be lower than RD because denominator of PAR (population) is larger

How do you calculate Population attributable risk (PAR)?

Calculated by
PGO - CGO

PGO \= occurrence in total population (a+b)/total population

What is socio economic position (SEP)

Are social and economic factors that influence what positions individuals are groups hold within the structure of a society.

Is a relative measure

How can SEP be measured

Education
Income
Occupation
Housing
Assets and health

Deprivation
Access to resources (e.g. how many fast food joints are near home)
Income inequality
Literacy rates

What is deprivation

is a state of observable and demonstrable disadvantage relative to the local community or the wider society to which an individual or group belongs to

Measures focus on material deprivation

what does it mean to live in poverty

Living in poverty means lack of income and resources which would normally lead to a normative living standard

What is the social gradient

Social gradient in health refers to the relationship between inequalities in population health and inequalities in social status. ... Generally, as SES increases, health status increases.

Why is population dada needed

To measure trends in births, mortality, morbidity (illness), and migration

To look at trends in unemployment, crime, health service utilisation, voter turnouts, educational pathways, etc

what is the census

The census tells us who we are and where we are going as a nation, and helps our communities determine where to build everything from schools to supermarkets, and from homes to hospitals. It helps the government decide how to distribute funds and assistance to states and localities

What is the integrated data infrastructure (IDI)

Large data repository that links de-identified data (data stripped of all 'direct identifiers) about people who have used government services

What is a population structure

age-sex structure

events determine population structure but can also affect events

is a function of previous patterns and trends

What is a population composition

population structure by attributes other than age and sex

What is numerical ageing

Absolute increase in elderly population

Reflects previous demographic patterns

what is structural ageing

Increase in the proportion of population that is elderly

Driven by decrease in fertility rates

Natural decline of population

occurs when there are more deaths than births in a population
- A combination of absolute and structural ageing
- More elderly \= more deaths

Absolute decline of the population

Occurs when there is insufficient migration to replace the lost births and increased deaths

What is the dependency ration

Child:
(0-14 years/working age)*100

Elderly:
(more than 65 years/working age)*100

Total: (youth+elderly/working age)*100

What is controlling?

reducing incidence and prevalence

What is mitigating

avoid overwhelming health services

what is suppressing diseases

reduce to a low level to minimise health effects

what is eliminating

reduce to 0 in a country or region

What is eradication?

reduce to 0 at a global level

What is the basic reproduction number

Is the mean number of infections directly generated by 1 case in a population where all individuals are susceptible to infection

What is the effective reproduction number

Mean number of additional infections caused by an initial infection at a specific time

If the effective reproduction is more than 1, then there is an exponential increase

Stopping an outbreak means reducing reproduction number to less than 1

What is the social safety net

It protects vulnerable populations from pandemic infections but when vulnerable populations are instead, exposed to unintended consequences (e.g. lockdowns and economic recessions)