PopH, PAL, and SFM Flashcards
Define descriptive and analytic epidemiology
Descriptive epidemiology refers to the who, what, when, where, why of cases, can identify patterns among cases and in populations by time, place and person - enables hypothesis generation
Analytic epidemiology, compares caharacteristsic between groups or populations and attempts to find a causal relationship or association for differeences, and quantify this relationshp - enables hypothesis testing
Provide examples of occupational hazards
Hazard is any source or situation that has the potential to cause harm to workers.
Situational hazards: psychosocial(short term overload, failing to cope, sudden horror or terror, bullying and harassment), safety (situations that can cause accident, trauma or injury; slips, trips and falls; workplace layout; heigh related hazards), ergonomics (manual handling, repetitive work, long working duration, posture and body movements), mixed basis (sick building syndrome, fire hazard)
Hazards of specific agent/form of energy: chem (gas, fume , particulate, mied eg machine smoke and tobacco smoke), phys (noise, electricity, lighting, barometic pressure, radiation, vibration and temperature), biological
Define occ dest of health
Various factors related to a person’s work or occupation that can affect their physical, mental, and social well-being
These determinants include aspects of the work environment – hazards or occupational factors
Other occupational determinants of health include
type of job
work hours
income and job security
access to healthcare and other resources
Define social determinants of health
Social determinants are social features that increase the risk of illness through their influence on biomedical and behavioural factors, as well as impacting on health directly.
Social determinants are referred to as the “causes of the causes of illness”
The social determinants of health are defined by the World Health Organisation as:
“The circumstances in which people are born, grow, live, work, and age, and the systems put in place to deal with illness. The conditions in which people live and die are, in turn, shaped by political, social, and economic forces.”
HI
Calculate odds ratio
Definition:
Relative associations are a ratio of proportions, and apply to measures of incidence, prevalence and mortality.
The most common relative associations are:
risk ratio (relative risk) - ratio of incidence of outcome in two exposure groups- obtain from rcts and cohort studies prevalence ratio - ratio of prevalence of outcome in two exposure groups:obtain from cross-sectional study odds ratio - ratio of odds of outcome in two exposure groups.- obtained from case control studies
The choice of measure depends on the study design.
The risk ratio is calculated in studies where participants are followed over time and the development of the outcome is measured:
cohort studies randomised controlled trials. RR = (incidence in the exposed group) / (incidence in the unexposed group)
To calculate the risk ratio from a contingency table:
Calculate the incidence in the exposed group (a/a+b) Calculate the incidence in the unexposed group (c/c+d) Divide the answer from (1) by the answer in (2)
Formula:
RR = (a/a+b) / (c/c+d)
Odds is the ratio of belonging to one group compared to THE OTHER.
The odds of exposure in the case group = exposed cases / unexposed cases. The odds of exposure in the control group = exposed controls / unexposed controls.
Calculate risk ratio
Recall ratio is a comparison of two independent variables i.e. A/B
Risk ratio or relative risk, calculated in studies where people are followed over time, and the development of an outcome is then measured e.g. cohort or RCTs.
RR = (incidence in the exposed group) / (incidence in the unexposed group)
To calculate the risk ratio from a contingency table:
Calculate the incidence in the exposed group (a/a+b) Calculate the incidence in the unexposed group (c/c+d) Divide the answer from (1) by the answer in (2)
Formula:
RR = (a/a+b) / (c/c+d)
where a is exposed and disease, b is exposed and no disease, c is no exposed and disease, d is no exposure and no disease
Calculate rate difference
The rate difference is calculated by subtracting the incidence rate in the comparison group from the incidence rate in the group of interest. As it is an absolute measure two compare the rates in two groups, the units of measurement are the reported (and are the same as the units used in reporting the rates).
The correct answer is: 90.1-44.9 = 45.2 per 1000 person years
Interpret 95% CI
A confidence interval gives us a range of values within which we are reasonably confident the true population value lies. cf The p-value tells us the strength of the evidence against the null hypothesis.
Confidence intervals and p-values are both derived from the size of the difference (the effect size or point estimate) and it’s standard error, therefore they are closely related.
If the 95% CI does not contain the null value (i.e. the value indicating no difference), then the p-value will be smaller than 0.05.
note:
When comparing means between two groups, the value of no difference is 0
When comparing proportions using a ratio, the value of no difference is 1
crossing 1//
The 95% confidence interval is calculated as:
Lower bound: sample mean/prop – (1.96 x SE)
Upper bound: sample mean/prop + (1.96 x SE)
Calculate se
The standard error is therefore the variation in means from multiple sets of measurements.
Sd/ root(n)
Define determinants of health
Health determinants can be defined as:
(i) attributes, characteristics or exposures that increase or decrease the likelihood that a person will develop a disease or disorder.
(ii) a broad range of personal, social, economic and environmental factors that determine individual and population health.
Determinants of health include both risk factors and protective factors.
A risk factor is any factor which increases the likelihood of a person developing a health disorder or health condition.
Protective factors can reduce the likelihood of developing disease, or slow the progression and severity of the disease.
Determinants may be modifiable or non-modifiable.
Modifiable factors are those that can be changed, such as lifestyle, social and environmental factors.
Non-modifiable factors are those that cannot be changed, such as age, sex (biological, not gender), and ethnicity.
Defien environmental determinants of health
Environmental health addresses all the [physical], chemical, and biological factors [external]to a person, and all the related factors impacting [behaviours]. It encompasses
the [assessment ] and control of those environmental factors that can potentially affect health. It is targeted towards preventing [disease ] and creating health-supportive
[environments].
Interpret p values and explan why they might be problematic
A statistical significance test is used to test the null hypothesis and a p-value is obtained from this test.
We reject the null hypothesis (H0) in favour of the alternative hypothesis (HA), if there is sufficient strength of evidence against the null hypothesis.
The strength of evidence against the null hypothesis is examined through formal statistical testing. Statistical tests provide a test statistic and a corresponding p-value.
A p-value is the probability of getting a result like the one observed if the null hypothesis is true.
In other words, it is the chance that the observed estimate in your sample could simply be a result of sampling variation.
If the p-value is large, there is a reasonable chance of getting the observed estimate if the null hypothesis was true.
For a p-value of 0.1, there is a 10% chance of getting the observed estimate if the null hypothesis was true. For a p-value of 0.001, there is a 0.1% chance of getting the observed estimate if the null hypothesis was true.
The smaller the p-value, the less likely it is that the observed estimate based on the study sample could be due to chance, and there is greater evidence that the null hypothesis can be rejected.
P-values are interpreted the same way no matter which actual statistical test was used.
Interpreting statistical significance from p-values is controversial. The general rules of thumb are:
p>0.1 is weak evidence against the null hypothesis
p<0.001 very strong evidence against the null hypothesis
p<0.05 generally reported as statistically significant - deemed small enough to justify rejection of the null hypothesis.
It is sufficient to display p-values to two significant figures (e.g. p=0.25, or p=0.015). It is common practice to display p-values less than in 1 in 1000 as p<0.001.
Define the study designs, their benefits and disadvantages
pidemiological study designs
Case series: describes the characteristics of a group of people who have the same disease or exposure. Ecological studies: Ecological studies collect data at the population level, for example measles rates in different countries. The disease and exposure of interest are measured in different populations and their relationship examined. Cross-sectional surveys: information is collected from a defined population at a single point in time providing a "snapshot" of the health status of a population. Often involves collecting information using questionnaire. Often referred to as prevalence surveys. Case-control studies: groups of diseased (cases) and non-diseased (controls) subjects are selected and compared. Cohort studies: groups of exposed and non-exposed individuals are followed over time to measure the development of disease. Intervention studies: study participants are randomly allocated to treatment and control groups and the outcomes in each group are compared.
n.b. cohort and case control are two sides of the same coin. cohort follows exposure to outcome, case controls follows outcome to expoure
List and describe the different incidences
- cumulate
- and incidence rates
List factors that influence prevalence and describe the relationship between incidence and prevalence
Describe and provide examples of the epidemiological triad
The epidemiological triad is the traditional model to understand infectious disease causation. It shows the interaction between:
an infectious agent, it's potential host, the transmission process (how the disease is spread) and how all of these may be influenced by the environment.
An epidemic may therefore result from:
A recent increase in amount or virulence of the agent, The recent introduction of the agent into a setting where it has not been before, An enhanced mode of transmission so that more susceptible persons are exposed, A change in the susceptibility of the host response to the agent, and/or Factors that increase host exposure or involve introduction through new portals of entry
host:age, sex, race, religion, cultural, family background, immune status, previous diseases, customs, occn, marital status
environment: temperature/climate, food, pollution, noise, water, altitude, crowding, housing, neighbourhood (vefctors, reservoirs etc)
agent: bio chem phys
e.g. Dengue fever
Agent: Flaviviridae, Flavivirus, Dengue virus
Host: Humans, intermediate hosts: mosquitos (Stegomyia (Aedes) aegypti, S. albopictus, S. polynesiensis, S. Scutellaris), monkeys in Malaysia and Africa
Environment: breeding grounds for mosquitoes like stagnant water, open gutters, centralized but unclean water supply, lack of access to supportive care, urbanization, deforestation, climate change
Define surveillance
Surveillance is defined as:
“The ongoing systematic collection, analysis and interpretation of health data essential for planning, implementing and evaluating public health data”.1
The goal of public health surveillance is to provide information that can be used for action by public health personnel, government leaders, and the public.
Active, passive, surveillance and sentinel:
n passive surveillance, laboratories, doctors or other healthcare professionals regularly report cases of disease to the local or state health department. Notifiable diseases such as measles are reported under passive surveillance systems
In active surveillance, local or state health departments initiate the collection of specific cases of disease from laboratories, doctors or other healthcare professionals. An example of active surveillance is the screening of hospital patients on admission for nasal colonisation with MRSA.
Sentinal surveillance: health events are reported by health professionals who are part of a limited network that is deliberately selected to represent a geographic area or specific reporting group. It is used when high quality information is needed about a disease that can not be obtained through passive surveillance.
An example is the Victorian Sentinel Practice Influenza Network, which is a general practice-based program that provides information about the proportion of patients with influenza-like illness
Syndromic surveillance: focuses on one or more symptoms rather than a doctor diagnosed or laboratory confirmed disease. Syndromic surveillance is commonly used to improve early detection of outbreaks.
An example is the Flutracker system, that collects weekly information on flu-like symptoms therefore providing an early warning of increased activity before data on confirmed cases is available.
List examples of notifiable diseases
- campylobacterioriss
- salmonellosis
- measles
-anthax - Hepatities BCD
- Chlamydia
- Malaraia
- Legionelloiss
- CJD
- plague
Calculate incidence rate
The incidence rate of avoidable hospitalisation in Aboriginal children was twice that of non-Aboriginal children. The rate ratio is a relative comparison of the incidence rates in the two groups. The incidence rate in the group of interest is divided by the incidence in the comparison group. As it is a ratio, there are no units of measurement.
The correct answer is: 90.1/44.9 = 2.01
i.e no units
Define crude mortality rate, and distinguish with age adjusted mortality rate
The crude mortality rate reflects the mortality experience and age distribution of a community, whereas the age adjusted mortality rate eliminates any differences in the age distribution. If community A’s age-adjusted mortality rate is lower than its crude rate then that indicates that its population is older.
TRUE OR FALSE Cause-specific mortality rate uses mid year population in denominatior
TRUE
but maternal mortality, age-specific, and infant do not
Define neonatal mortality rate
The neonatal mortality rate is the probability of dying within the first 28 days of life per 1000 live births.
What is a key feature of incidence
Incidence is the number of new cases that occur during a specified period of time in a population at risk of developing the disease.
Describe period prevalence
Period prevalence is the proportion of existing cases in a defined population over a specified period of time.
Define cumulative incidence
Cumulative incidence is the proportion of an initially disease-free population that develops disease during a specified time. The cumulative incidence is calculated as 15/1000 giving 1.5% (or 15 per 1000 women).
What is the difference between a rate and a proporiton
A proportion is a comparison of two independent varaibles, whrea numberot is included indenominator. EG prev, incidence, mortality
Rate is a special case of proportion, includes a specific time period
Definition of prevalence
The proportion in a defined population who have a specific disease at a certain point or piod of time: no of people with disease ata given time/period divided by no in totatl popoulation at time
Can be expressed as percentage or as per 100, 1000
Distinguish between cumulative incidence and incidence rate
- cumulative: proportion of new cases of disesase in population i in a fgiben period
- divdided by pop at risk in psecifc time priod
Rperesents risk of developing diseae
percent, %/yr, per 1000, per 100k
Inc rates: how hast new cases of disease are occuring in pipulation aat risk
multiplied by time interval
expressed in person-time units:
note: 100 new cases of cholera, divided by population at risk of 5000, times 5 years
= 0.004 new cases per year
OR 4 per 1000 person years
Assumption in calculation= all persons followed for total interval
List the two factors within the envirionemnt which can affect health
- natural environemnt
- built environment
List the principle exposures of environmental health
Bio
Phys
Chem
Describe some environmental health risk assessments
- dose respinse
- exposure
- hazard*’
- risk characterisation: Risk characterisation examines how well the data support conclusions about the nature and extent of the risk from exposure to environmental stressors.
Define risk managemtn
Risk management involves consideration of reducing the hazard at source, removing exposures at the individual level, and removing exposures at community levels.
Idnetify and assesss, develop control measures to reduce it, and monitor effectiveness of control measures
Once the hazard has been identified - risk assessment
Probability, the likelihood of exposure to the hazard
Level of severity of disease or injury that occurs
A combination of both
Influenced by
Hazard nature
Dose-response relationship
Workplace policy
Individual factors
List the steps to surveillance process
- data collection
- data analysi
- data interpretation
- data dissemination
- link to action
List some categories of epidemic and outbreak disease patterns
Sporadic refers to a disease that occurs infrequently and irregularly.
Endemic refers to the constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area. In other words, it is the amount of a particular disease that is usually present in a community and is often referred to as the baseline level. For example, malaria is endemic in much of Africa.
Hyperendemic refers to persistent, high levels of disease occurrence.
Epidemic refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area.
Outbreak carries the same definition of epidemic, but is often used for a more limited geographic area.
Cluster refers to an aggregation of cases grouped in place and time that are suspected to be greater than the number expected, even though the expected number may not be known.
Pandemic refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people. Examples are the influenza pandemics of 1918, 1957 and 1968; HIV and multi-drug resistant tuberculosis
Describe patterns of epidemic
Epidemics can be classified according to their manner of spread through a population. There are two main types:
Common-source
Point
Continuous
Intermittent
Propagated
A common-source outbreak is one in which a group of persons are all exposed to an infectious agent or a toxin from the same source.
A propagated outbreak results from transmission from one person to another.
The progress of an outbreak is studied using an epidemic curve. This is a plot of the number of cases of disease against time relative to the date of onset. From it’s shape we can identify the type of epidemic.
Describe the hierarchy of evidence
The hierarchy of evidence
Meta-analysis of randomised controlled trials Randomised controlled trial Cohort study Case-control study Cross-sectional study Ecological study Case series
List the advantages and disadvantages of case series
Advantages
Disadvantages
Describes the demographics, presentation or prognosis of people who have a particular disease.
Has no comparison group.
Can draw attention to an emerging issue and lead to confirmatory studies using higher quality study designs
List the advantages and disadvantages of ecological or correlational studies
Ecological level variables may be:
aggregrate measures: summaries of observations derived from individuals (e.g. incidence of a disease, proportion of smokers, area level deprivation indices), environmental measures (e.g. air pollution level or hours of sunlight) global measures for which there is no distinct individual level measure (e.g. Gross Domestic Product, population density)
Advantages:
Useful for comparing health between different populations or over time
Useful for highlighting issues that can be investigated in future studies
Inexpensive and quick as can use existing sources of data, such as published statistics
Useful in environmental epidemiology where we often can not measure exposures at the individual level for large numbers of subjects
Useful for the evaluation of the impact of new policies, programmes and legislation on the population
Negatives:
Has no comparison group.
The people who are exposed may not be the same ones who experience the outcome. If the associations detected at group level do not hold on an individual level, the study suffers from a type of bias known as ecological fallacy.
Describe cross-sectional studies
In cross-sectional studies, information is collected from a defined population at a single point in time without any follow-up, providing a “snapshot” of their health.
Because they measure health status at a point in time, they are often called prevalence studies.
Cross-sectional studies usually involve asking participants a series of questions using a questionnaire.
Cross-sectional studies may be:
descriptive: they measure one parameter, e.g. the prevalence of type 2 diabetes in adults over the age of 40y (often called prevalence studies.) analytical: the measure exposure associations with outcomes, e.g. the association between obesity and type 2 diabetes in the same population.
Advantages:
Relatively inexpensive and easy to conduct
Can provide information on multiple exposures and outcomes
Assess the health needs of a population
Useful for studying asymptomatic conditions where patients may not present to doctors, such as high blood pressure. The clinical iceberg is a recognised phenomenon in which medical services are only aware of symptomatic patients, i.e. those above the water line.
Diasadvantages:
Cannot determine causality: measurements of the outcome and exposure are made at the same time, cross-sectional studies cannot be used to determine whether a particular exposure caused the disease. In addition, the exposure may be secondary to the disease (reverse causality).
Selection bias: subjects with an interest in the topic may be more likely to volunteer to participate. Selection using random sampling may still result in bias if the response rate to selection is low.
Recall bias: cases of disease may be more aware of suspected exposures than participants without disease
Confounding: association with a third variable that provides an alternative explanation for the observed association between the exposure and the outcome.
note effect modifier – disappears with adjustment of effect modifier e.g. age adjusted ratio/multivar analysis
Describe case control studies
Case-control studies start with cases of a disease and uses a comparison of controls, who are similar to cases but do not have the disease.
Both groups are asked about their exposure to previous risk factors. Sometimes exposure information is extracted from records.
Case-control studies compare the frequency of exposure to a suspected risk factor in cases with the frequency of exposure to that risk factor in controls. The summary measure expressing the association between the exposure and disease is known as the odds ratio (see below).
Advantages:
- evaluate many different exposures
- useful fro rare diseases becuase they start off with caes
- quick and cheap tp perform
Disadvantages:
- not good for rare exposures: bec may involve small numbers
- control selection: can be dif to obtain controls that adequately represent the population that cases come from
- info bias: recall bias and observer or interviewr bases (if case and control, info not comparable)
- confounding
- reverse causality: outcome already occurred, dif to tell if exposure preceded outcome
- selection bia: arises if cases and controls are no choen independently of the exposures being studied
\
eg smoking and lung cancer
Describe cohort studies
In cohort studies a group of people are followed over time to study what happens to them.
Information about exposures are usually measured at the start of the study among people who have not yet developed the disease outcome of interest. They are then followed over time to evaluate the occurrence of the outcome. This is known as a prospective cohort study.
Sometimes, a retrospective cohort study is conducted where the disease has already occurred and investigators can collect exposure data from pre-existing records. This design is useful for studying long-term exposure effects as the investigators do not need to wait for the disease to develop in a prospective study.
Risk ratio
The main advantage of cohort studies is that the time sequence of events can be determined.
- exposure information is measured before the onset of disease so the temporal relationship between exposure and outcome is clear
- provide a direct measure of incidence (risk)
- among observational studies, cohort studies provide best evidence that an exposure-outcome association is causal.
- can assess multiple exposures and multiple outcomes allowing sub-analyses to be conducted
Disadvantges:
- Time consuming and expensive as can involve a large number of people being followed for many years.
- not suitable to study rare diseases
- loss to follow up bias: type of selection bias – move, oose contact, grow tired, become too ill
- confoudning: the exposed and unexposed groups of participants will differ on factors other than the exposure being investigated.
Describe RCTs
Randomisation is important because it ensures that the two groups are similar on all aspects (e.g. age, sex, general health, socio-demographic factors) other than the intervention. If one group were in some way less healthy than the other at the start this might make this group look worse even if the intervention had no effect.
Ideally, neither the participants nor the investigators should know which intervention group patients belong to (called double blinding) so that neither of them can influence the outcome of the study.
Best for intervention studies
RR or hazard ratio: comparing incidence rates rather than cumulative incidences
Advantages:
- good evidence of causality - strongest study design that an intervention led to the outcome.
- Randomisation - ensures that both groups have an equal chance of receiving the intervention and that they have similar characteristics. The effect of the intervention can be studies without other factors influencing the outcome (confounding).
Disadvantages:
- Measurement bias may arise if double blinding can not be ensured.
- May need to include a large number of participants.
- May not be suitable in situations where not giving an intervention may be inappropriate or unethical. Can allocate people to harmful exposures.
- can be expensive
- randomisation does not guarantee group equivalence if the numbers of participants are small
Define multifactorial causation
Multi-factorial causation comprises several factors, or components, that result in sufficient cause.
Define a necessary cause
A necessary cause will always produce disease regardless of other factors
Describe causal factors
There are four types of factors involved in the causation of disease:
- Predisposing factors: age, sex, genetics, previous illness.
Enabling factors: factors that favour the development of disease, such as poor nutrition, low income, inadequate medical care, or assist in the recovery from disease. Social determinants of health are important enabling factors.
Precipitating factors: exposure to a specific disease agent.
Reinforcing factors: repeated exposure to factors or environmental conditions that may aggravate an established condition.
This classification underpins the PRECEDE-PROCEED model that is used extensively in health promotion research to identify factors that predispose, enable and reinforce an individuals engagement with health risk behaviours.
For example, knowledge and attitudes about smoking was identified as a predisposing factor in a study of smoking during pregnancy in Aboriginal and Torres Strait Islander women (MJA 2009; 190:557-561)
List Hill’s criteria for causation
It is not an absolute requirement that all criteria are met in order for a exposure to be considered causal. However, a temporal association and biological plausibility are ESSENTIAL criteria.’
Temporality
The exposure precedes the occurrence of disease (essential). Is easier to establish in a prospective cohort study than a case-control study. Also important to understand the length of the interval between exposure and disease.
Plausibility
The causal explanation makes biological sense (essential)
Replication & consistency
Similar results from other studies in a variety of different situations and in different populations that are unlikely to share the same bias.
Strength
What is the strength of association between the exposure and disease? A relative risk (or odds ratio) of 3 or 4 is less likely to be due to bias than one of 2 or less.
Dose-response relationship
Is increased exposure to the possible cause associated with increased effect?
Reversibility (cessation of exposure)
Does the removal or reduction of a possible cause lead to a reduction in the disease risk?
Specificity
Are the findings specific? Is the association specific to one disease?
Many diseases have several causes and many exposures cause several diseases (e.g. tobacco). However, may be useful for some exposures, for example where an association may be limited to a particular group with a particular environmental exposure.
Support from experimental data
Including animal or in vitro studies and intervention studies in humans
What are the four types of systematic error or bias?
- Recall bias
- Observer bias
- Measurement bias (or information bias)
- Selection bias
Define risk factors
The term “risk factor” is commonly used to describe factors that are positively associated with the risk of developing a disease, but are not sufficient to cause disease. Some risk factors are associated with several diseases (e.g. tobacco smoking), and some diseases (e.g. coronary heart disease) are associated with several risk factors.
Define cause
An event, condition, or characteristic [or a combination of these factors] that plays an essential role in producing the occurrence of disease. (Webb & Bain p239)
In other words, a cause of a disease increases a person’s risk of developing the disease.
Describe the types of causes
A necessary cause - any agent that is required for the development of a given disease (e.g. a specific infectious agent). An outcome cannot develop in its absence. e.g. presence of A necessary cause - any agent that is required for the development of a given disease (e.g. a specific infectious agent). An outcome cannot develop in its absence. e.g. P.carinii and pneumonia (but not all who have P.carinii develop pneumonia…), HIV infection for AIDS
A component cause - a factor that contributes towards disease causation but is not sufficient to cause disease on its own e.g. smoking and lung cancer
A sufficient cause - a factor (or usually a combination of factors) that will inevitably produce disease.
OR
A minimum set of conditions and events that are sufficient for the outcome to occur.
This is a feature of multi-factorial causation e.g. smoking, and asbestos, for lung cancer.
n.b. Some can be both necessary and sufficient e.g. Tay-Sachs mutation
Equally, some causes may be neither necessary not sufficient e.g. for complex chronic diseases e.g. cancer
Describe multifactorial causation
Multi-factorial causation therefore comprises several factors, or components, that result in “sufficient” cause.
It is not necessary to identify all of the components of a sufficient cause before prevention can be successful.
The removal of one component may interfere with the others and therefore prevent the development of the outcome.
Chronic diseases are multi-factorial - there are many components, none of which are strictly necessary or sufficient on their own to cause disease. See the smoking and lung cancer example below.
List the questions ask to determine causality
- Consider alternative non-causal explanations.
Could the observed association be an artefact due to chance, bias or confounding?
Is the association due to a chance occurrence? Is it due to a flaw in the methodology (bias)? Is it due to some other factor linked to both the exposure and the outcome (confounding)?
- A formal evaluation of whether an observed association is causal
If we are confident from our critical appraisal of a study that the association is not due to chance, bias or confounding we can consider additional criteria to assess whether the association is causal.
Unfortunately, there is no clear answer to how big an effect should be for it to be meaningful.
An relative risk of 2.0 is generally considered to be strong and therefore practically significant.
A RR of less than 2 should not be immediately dismissed without considering the risk (i.e the incidence) in the unexposed group or the total population under consideration.
A small association for a relatively common disease can result in a large number of additional cases; conversely a moderate or strong association for a rare disease may only result in a few additional cases.
What are the criteria for confounding variables?
For something to be a confounder it must:
- be a risk factor for the disease in it’s own right, and
- be associated with the risk factor of interest
- must not be an intermediate factor between the exposure and outcomeNote:
A confounder may:
Account for all or part of an apparent association
May cause an overestimate or an underestimate of a true association.
What is random error and what are the types of random error? Describe the consequences of random and systematic error on results
Each sample will include slightly different people - their characteristics will be slightly different from those in other samples - just by chance.
This is known as random sampling error. It is one of the three main sources of random error in addition to biological variation and measurement error.
a) Little systematic or random error: an experienced shooter using a gun with the sights properly aligned - shots will cluster closely around the bulls-eye. The estimate is precise and accurate.
b) Systematic error but little random error: an experienced shooter using a gun with sights not aligned correctly - shots will cluster closely but will not be accurate as consistently falling to the right. The estimate is precise but not accurate.
c) Random error but little systematic error: a less experienced shooter using the first gun - will be accurate but the shots would be more spread out. The result will not precise but will be accurate.
d) Random and systematic error: the less experienced shooter using the second gun. The result will not be precise nor accurate.
Identify key social, biological, epidemiological, and environmental risk
factors for respiratory disorders focusing on Asthma and COPD
What do the overlapping risk factors for NCD/CRD’s tell us?
* Both often share environmental/behavioural risk factors
(e.g. tobacco, nutrition, indoor and outdoor air pollution, and
sedentary lifestyle)
* Tobacco smoking is the best-identified risk factor for many
non-communicable diseases, including chronic respiratory
disease
Comorbidities (See other q)
Although the absolute estimates of the prevalence and health burden of chronic respiratory diseases increased between 1990
and 2017, there were decreases in age-standardised estimates of prevalence (−14·3%), mortality (−42·6%), and DALYs
(−38·2%) in the same period.
* Smoking accounted for the highest proportion of disability attributable to chronic respiratory disease in all regions for men.
* However, for women, the leading risk factor for disability varied by region: household air pollution from solid fuel use in south
Asia and sub-Saharan Africa, exposure to ambient particulate matter in the southeast Asia, east Asia, and Oceania and the
north Africa and Middle East super-regions, and smoking in all other super-regions
Between 1990 and 2017, the total number of deaths due to chronic respiratory diseases increased by 18.0%, from
3.32 million in 1990 to 3.91 million in 2017.
* Regions with a low Socio-demographic index had the highest mortality and DALYs. The global trends of
mortality and DALY rates for chronic respiratory diseases varied by age, sex, region, and disease pattern
* Smoking remained the major risk factor for mortality due to COPD and asthma.
* Pollution from particulate matter was the major contributor to deaths from COPD in regions with a low Socio-
demographic index.
* Since 2013, a high body mass index has become the principal risk factor for asthma
-
Key Results:
* Both socioeconomic and environmental factors impact CRD mortality rates.
* Between 2010 and 2017, approximately 21.4 million people died from chronic respiratory diseases in the
countries studied’
* 1% increase in GDP per capita results in a 20% increase in the CRD mortality rate.
* Mortality increases with greater exposure to PM2.5
* However, an extra year of schooling reduces the mortality rate by 4.79% (− 0.0479).
* Further, rate of urbanization is negatively associated with the CRD death rate (− 0.0252)*
* the impact of pollution on the risk of morbidity due to CRD is greater that its impact on mortality, since urban
areas are expected to offer better access to health care facilities and technologies
Discuss the concept of comorbidities with respect to chronic diseases
People with chronic respiratory conditions often have other chronic and long-term conditions.
These ‘comorbidities’ are defined as the concurrent existence and occurrence of two or more medically diagnosed diseases in the same individual, with the diagnosis of each contributing disease based on established, widely recognized criteria.
Comorbidity is not a sequel or complication of one disease but two separate diagnosis may have common underlying risk factors.
Among people aged 45 and over with COPD:
* 55% had arthritis (compared with 33% for people without COPD)
* 43% had asthma (compared with 11% for people without COPD)
Among people aged 45 and over with asthma:
* 49% had arthritis (compared with 32% among people without asthma)
* 17% had COPD (compared with 3.1% among people without asthma)
Among people aged 45 and over with asthma:
*49% had arthritis (compared with 32% among people
without asthma)
*37% had back problems (compared with 24% among
people without asthma)
*34% had mental and behavioural conditions (compared
with 20% among people without asthma)
*17% had COPD (compared with 3.1% among people
without asthma)
List some health challenges associated with climate change
- smoke and bushfires
- Drought has both physiological effects as well as serious mental health effects for communities
Flooding and storm damage affects health of affected communities
Towns without water can see health effects emerge
Health services are compromised by extreme weather events including fires, droughts and floods
Changes in patterns of diseases – particularly infections
Describe how heat is a serious health risk
Heat is the natural event that has the highest mortality in Australia
Not well reflected in our health data
Very high temperatures are an emerging challenge for human habitation in parts of Australia
Regional variation in temperature is central to understanding the likely health and biological impacts of rising temperatures
–
side note: not exercising because of heat:
Loss of muscle tone and strength
Metabolic changes including glucose, insulin
Blood pressure and HR
Mental health affects
Bowel and bladder function
Chronic disease management
Risk of falling increases
Exercise is a powerful ‘anti-aging’ intervention. Not exercising can increase frailty.
Models for environmental influence on health
- many models (lancet countdown, ecological determinants of health, doughnut for anthropocene)
- include climate, weather, biodiversity; impact on air, food, water, where and how we live
- biopsychosoccial model + environmenyt
What is the aim of preventive medicine?
The aim of preventive medicine is the absence of disease, either by:
a)preventing the occurrence of a disease; or
b)halting disease progression; or
c)averting complications after its onset.
Preventive medicine can be practised by governmental agencies, primary care physicians and the individual himself.
Disease prevention is everyone’s business.
List some agencies tasked with health prevention
- WHO
- UN agencies e.g. UNICEF, UNFPA, UNDP…
- Word Bank
- OECD
- Bilateral agencies
- International Philanthropy e.g. Red Cross, MSF
List and briefly describe the levels of health prevention
- primary
- preventing disease before it happens
- modifying existing risk factors e.g. bike helmets, tobacco cessation
- preventing development of risk factors e.g. boke trails located away from vehicles and policies limiting youth from purchasing tobacco - secondary
- identifying disease before problem becomes serious e.g. NBS, mammography, BMI screening, BP measurement, regular check ups for smokers
- tertiary
- preventing complications of disease e.g. post-stroke rehabilitation, blood sugar-lowering medications for diabetes, physical therapy for back injury
Primordial prevention targets social and economic policies affecting health.
It is to prevent the emergence of predisposing social and environmental conditions that can lead to causation of disease.
It is often beyond the control of clinicians as it requires policy-level interventions.
But clinicians can be advocates for change.
quaternary prevention
- action taken to protect individuals from medical interventions that are likely to cause more harm than good
- the goal is to reduce overmedicalisation and iatrogenic harm
Describe the components of health promotion
The key principles of health improvement include:
- a broad and positive concept of health
- participant involvement
- action, and competencies for action
- a settings perspective
- equity in health
Health promotion is defined as the process of enabling people to increase control over, and to improve their health, through a) Building Healthy Public Policy; b) Creating Supportive Environments; c) Strengthening Community Action; d) Developing Personal Skills; and e) Reorienting Health Services.
Describe the links between health promotion and prevention and SDH
Health promotion is defined as the process of enabling people to increase control over, and to improve their health, through a) Building Healthy Public Policy; b) Creating Supportive Environments; c) Strengthening Community Action; d) Developing Personal Skills; and e) Reorienting Health Services.
Disease or health prevention is defined as measures not only to prevent the occurrence of disease, such as risk factor reduction, but also to arrest its progress and reduce its consequences once established.
Equity means fairness. Equity in health means that people’s needs guide the distribution of opportunities for well-being. (This also applies to health services access & availability).
Individuals live behave and are influenced by various factors operating at different levels e.g. individual, interpersonal, organisational, community and public policy levels.
When considering the “three” levels of prevention do not forget the context, and person, place and time.
These levels, above, are also where SDH strategies are targeted e.g. a multi-level approach.
List and briefly describe the stages of health behaviour change
Stages include:
- 1: precontemplation and ignoring problems
- 2: contemplation, and weighing up the pros and cons of the problem
- 3: preparation, and planning behaviour changes
- 4: action and performing the behaviour
- 5: maintenance, and integration of new behaviours in daily life
e.g. IHD, asthma, pre-diabetic (T2D)
The missing element from this model is that relapse is not an exception but a normal part of human behaviour.
Doctors need to assist individuals to get back on course as part of a health promotion and prevention strategy.
Describe deficit discourse
- disempowering patterns of thought, language and practice
- represents people in terms of deficiencies and failures
- places responsibility for problems with affected individuals or communities, overlooking the larger socio-economic structures in which they are embedded
- rejecting deficient discourse does not ignore challenges or downplays it but highlights it, ways to alleviate it
- consequence: identity becomes defined in negative terms
Describe how social determinants impact CKD burden
Social and not biological differences are the primary cause of uneven burden of CKD
Multiple different explanatory pathways have been proposed
- primary renal disease explanations: higher incidence and greater severity — reflect processes that cannot be explained by epigenetic and/or SDH
- genetic differences – evidence varies
- early development explanations: attributed to adverse intrauterine environment affecting kidney development and predisposing to ESRD– supported by evidence
- socio-economic disadvantage increases ESRD incidence: supported by evidence
CKD and ESRF are the result of an additive process of acute and chronic insults to the kidney
*Health and disease follow a social gradient, where lower socioeconomic status is associated worse health outcomes
*SDH are critical to the creation and maintenance of health inequities - unfair and avoidable differences in health status
*SDH can be more important than individual behavior or health care in influencing health outcomes
*SDH are often represented in a way that makes sense to social and public health researchers, but can be hard to apply in a clinical setting
Acute and chronic insults can be made more prevalent by issues of human security: food, water, housing, environment and health.
These are turn impacted by issues of transport, service availability and quality, continuity of care, accessibility, culturally appropriate and safe care, quality, affordability etc
Notably, education and income are important factors influencing the inequitable distribution of CKD in Indigenous Australian populations.
Broader issues of education access/quality, social/community context, exonomic stabiity, health access and workforce , neighbourhood and built environemnt - all ultimately influenced by inequality
Burden of CKD is
a product of significant social and environmental security challenges, exacerbated by remote geography.
actors affecting water security
Water security is one of five determinants of human security, a social determinant of health.
- contamination by microbes
- calcificaiton of pipes
- buying water
Factors affecting housing security
Another determinant of human security.
- energy insecure due to pre-payment
- no building permits or qualifications required
- required maintenance but no tradies
- few facilities e.g. washing machines
- overcrowding
Food security
- prevalence higher in remote Indigenous communities comapred to asustralian population (31%, and likely underestimate)
- choosing between food and energy
- cost in healthy food 52% higher
Note: not just a remote issue
- Alice Springs, flooded highway
#### Geography
- similar size to sizable NSW towns e.g. Bathurst, Queanbeyan
- fewer supermarkets
- 5-7 hours or longer for nearby, if local is out
Describe issues of service delivery for CKD patientes in resourece limtied settings
Services for CKD and ESRF require a complex network of nurses, doctors, community workers, and physical infrastructure
Renal care in Central Australia
*The Alice Springs Renal unit is the largest single dialysis complex in the Southern Hemisphere
*Over 400 dialysis patients and nearly 1000 patients with CKD (2020)
*Covers area of 872,861 Km2
*17 remote communities, 15 language groups
*Services by the Alice Springs “Renal Mob:
*Inpatient, community and home dialysis hubs
*Peritoneal dialysis
*Renal transplantation services
*Interventional nephrology
*Chronic kidney disease clinics
*Transportation
HD units
Four HD units in Alice Springs
*Kidney Dialysis Unit at Alice Springs Hospital: Inpatient and acute HD, unstable patients
Three community units:
Note: Purple House/Western Desert Dialysis: renal patients who find it hard to engage with Western models of care
Nurse-led units outside Alice Springs
- Tennant Creek: Largest satellite unit outside of Alice Springs
- Smaller remote units
Note:
Many of our patients live remotely prior to starting dialysis, which can make CKD follow up difficult.
many patients may not have reliable electricity, food or medication security or working fridges when prescribing outpatient management.
HOME DIALYSIS HUBS
We have home dialysis hubs where patient can do dialysis in a unit in their own community:
- requires the patient to undergo home dialysis training with a buddy
PERITONEAL DIALYSIS
PD is a major issues:
- lack of suitable resources in many remote communities to do dialysis in their own home
- high infection rate.
RENAL TRANSPLANTATION
Renal transplantation also has its complications:
- high burden of comorbidities
- lack of available living donors
- difficulties in complex follow up in the remote communities.
It is a unit priority to try to work up and list and suitable patients for a transplant.
INTERVENTIONAL NEPHROLOGY
Alice Springs Renal Unit is one of the few interventional nephrology units in Australia.
For many of our patients English is the second, third or fourth language and ALOs can be very helpful in providing interpretation services here.
Providing care in remote settings require flexibility, adaptability and commitment
Strategies for prevention and provision of adequate care include:
Strategies for kidney disease prevention and providing adequate care
- target levels of prevention
Notice the difference between levels of prevention and healthcare
Public health can tackle primordial prevention.
Orimary healthcare can tackle primary prevention
Recommendations
Recommendations developed in consultation with First Nations communities across metropolitan, regional and remote areas of Australia.
**Includes 15 recommendations under 4 areas:
*Cultural safe and responsive kidney health care
*Screening and referral of chronic kidney disease
*Public awareness, education and self-management
*Models of care (CKD, ESRF, transplant)
Under each recommendation, report includes:
*Description/background
*Community voice
*Clinical evidence (incl. certainty of evidence)
*Cultural safety considerations
*Cost, capacity, equity, and resource implications
Describe the distribution of CKD in Australia
Mortality and morbidity from CKD is associated with increasing age and is unevenly distributed across Australian population
- highest burden over 65
- uneven distribution: Indigenous status, remote and very remote areas, social disadvantage
- data from Indigenous patients:
- fewer dying, but incidence not really changing
- treatment approach greater prevention programs
What are NCDs and what is the importance of NCDs?
NCDs are chronic diseases that cannot pass from one person to another. They develop slowly over time, and generally progress slowly.
Non-communicable diseases (NCDs) are the leading cause of preventable ill health, related disability and premature death in the world today.
The major groups of NCDs are:
*cardiovascular diseases
*non-hereditary cancers
*chronic respiratory disease
*diabetes
*mental health conditions
NCDs are associated with a high level of social and economic burden. This includes:
*reduced quality of life (often for many years)
*reduced productivity - affecting economic and social wellbeing for the individual, their family and community
*increased burden of health care for the individual, the family and society
What is the global impact of NCDs?
Non-communicable diseases (NCDs) kill 41 million people each year, equivalent to 71% of all deaths globally.
Premature death
*Each year, more than 15 million people die from a NCD between the ages of 30 and 69 years;
*85% of these “premature” deaths occur in low- and middle-income countries.
In Aus= low Socio-economic situations, regiognal and remote areas
These four groups of diseases account for over 80% of all premature NCD deaths.
*Cardiovascular diseases (17.9 million people annually),
*Cancers (9.3 million),
*Respiratory diseases (4.1 million),
*Diabetes (1.5 million).
Note: mental health not on WHO list.
Tobacco use, physical inactivity, harmful use of alcohol, unhealthy diets → increased risk of dying from a NCD.
*Tobacco accounts for >7.2 million deaths every year
* Excess salt/sodium intake→ 4.1 million annual deaths
*>50% of the 3.3 million annual deaths attributable to alcohol use are from NCDs, including cancer.
*insufficient physical activity → 1.6 million annual deaths
*Detection, screening & treatment of NCDs, as well as palliative care, are key components of the response to NCDs.
Metabolic risk factors contribute to four key metabolic changes that increase the risk of NCDs:
*raised blood pressure; ^[biggest]
*overweight/obesity;
*hyperglycemia (high blood glucose levels); and
*hyperlipidemia (high levels of fat in the blood).
The leading metabolic risk factor globally (→ death) is elevated BP, followed by overweight & obesity, and raised blood glucose.
What is the impact of NCDs in Australia?
- The five disease groups: cancer, MSK, CVD, mental health and SUDs and neurological conditions (instead of respiratory)
- vary in fatality (MSK not too much)- Mostly chronic and long-lasting conditions
- Cancer contributes most burden, and is very fatal
- NCDs = 90% deaths ^[2011]
- Disease burden, or DALYs, is not equally shared: NT, remote and very remote areas, and lowest socioeconomic group
Discuss trends in NCDs in rural and remote Australia
A clear trend of greater burden rates with increasing remoteness for:
*coronary heart disease
*chronic kidney disease
*chronic obstructive pulmonary disease (COPD)
*lung cancer
*stroke
*suicide
*self-inflicted injuries
*type 2 diabetes.
In contrast, anxiety disorders, dementia and depressive disorders showed lower rates of burden in more remote areas (AIHW 2019a).
Health inequalities in rural and remote areas may be due to factors, including:
*challenges in accessing health care or health professionals, such as specialists, allied health
*social determinants such as income, education and employment opportunities
*higher rates of risky behaviours such as tobacco smoking and alcohol use
*higher rates of occupational and physical risk, for example from farming or mining work and transport-related accidents.
Health risk factors are attributes, characteristics or exposures that increase the likelihood of a person developing a disease or health disorder.
Modifiable risk factors such as:
*tobacco smoking (people outside major cities had higher rates of current daily smoking)
*poor eating patterns
*risky alcohol consumption
*not getting enough exercise.
Note: prevalence of health risk factors increases with remoteness.
Note 2: median age of death decreases with remoteness
Discuss the intersection of Indigenous health and remoteness
Remoteness and Indigenous people
- in very remote areas, 47% of the population are Indigenous
- remote areas = 18%
- 1.7% in major cities (however most Indigenous people live in cities, or inner regional areas)
Central Australian statistics
*Life expectancy of Aboriginal people 20 years less than for non-Aboriginal Australians.
*considerably worse than other comparable indigenous populations, eg the first nation peoples of USA and Canada, and the Maōri of Aotearoa.
*Aboriginal boys born today have 45% chance of living to age 65 (81% for non-Aboriginal boys); Aboriginal girls have 54% chance of living to age 65 (89% for non-Aboriginal girls).
*Age standardised death rates for Aboriginal males are 2.8 times those for non-Aboriginal males; Age standardised death rates for Aboriginal females are 3.3 times those for non-Aboriginal females.
Note: potentially avoidable deaths
- 17% of all deaths in Australia
- rate increases with remoteness for both males and females (more in females?)
Discuss some key challenges in public health and care in managing NCDs in rural and remote settings
The way people in rural and remote areas access primary health care often differs to those in metropolitan areas.
*facilities are generally smaller, have less infrastructure, less capacity i.e. for testing and provide a broader range of services to a more widely distributed population.
*Rural and remote populations also rely more on general practitioners (GPs) to provide health care services, due to less availability of local specialist services (Department of Health 2016).
Note: NT nurse dependent
“Australians living in Remote and Very remote areas experience health workforce shortages, despite having a greater need for medical services and practitioners with a broader scope of practice” (AMA 2017).
*health professionals per 100,000 population generally decreased with remoteness
*rate of allied health professionals, dentists and pharmacists was lower in regional areas and lowest in Remote and Very remote areas
*rate of specialists substantially declined with increasing remoteness
*Full time nurses and midwives were highest out of all health professionals in rural and remote
GP supply was also unequally distributed as remoteness increased. Data indicate that the rate of GPs in 2017 increased with extreme remoteness, however, care should be taken in interpreting the data as work arrangements in these areas have the potential to be more complicated (NRHA 2017) e.g. part-time, no after hours.
A demonstration of the inverse care law.
when answering questions hink of, mgmt vs prevention, non-drug.med,profs
Provide the definition of a health system
“all actors, institutions and resources that undertake health care actions - where a health action is one where the primary intention is to improve health”.
What are the three broad goals of a health system?
-Attainment of the highest quality of health for a country given available resources
-Responsiveness to the expectations of the population
-Fairness of financial contributions-
What are the six building blocks of a health system?
- work force
- service delivery
- information
- medicines and technologies
- financing
- governance and leadership
List the outreach programs
Describe OHS requirements for outreach testing
Describe cultural determinants of location of death
