Module 3 Flashcards
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.
Difference between population and individual health
Population health tends to treat everyone within a population while Clinicians only treat individuals that are present with the disease.
How can we measure cause?
Epidemiology doesn’t determine the cause of disease in an individual. It determines the relationship or association between a given exposure and dis-ease in populations.
What is an early experiments that dictates the cause?
- James Lind’s experiment with scurvy in sailers. he took 12 scurvy patients and gave them all interventions. The final result was that citrus fruit resulted in prevention of scurvy.
- Observational study in lung cancer deaths vs amount of cigarettes smoked per day. Trend: increasing cigarettes a day results in increasing deaths.
Components of Bradford hill criteria
Temporality Strength of association Consistency of association Biological gradient Biological plausibility of association Specificity of association Reversibility
Bradford hill Criteria (1965) implication
Aids to thought, not all criteria have to be fufilled
What is Bradford hill Criteria?
The Bradford Hill criteria, otherwise known as Hill’s criteria for causation, are a group of minimal conditions necessary to provide adequate evidence of a causal relationship between an incidence and a possible consequence
In Bradford hill criteria
-Temporality
-The exposure occurs before the outcome with greater likelihood of causality in the absence of bias E.g smoking before lung cancer deaths.
In bradford hill criteria
-Strength of association
-The stronger an association, the more likely to be causal in absence of know biases (selection,information and confounding) E.g British doctor study had a RR of greater than 10.
In bradford hill criteria
-Consistency of association
-Replication of the findings by different investigators, at different times, in different places, with different methods. E.g multiple studies show the same results for doctor and lung cancer study.
In bradford hill criteria
-Biological gradient (dose-response)
-Incremental change in disease rates in conjunction with corresponding changes in exposure. E.g death rate increases as cigarettes per day increases.
In bradford hill criteria
-Biological plausibility of association
-Does the association make sense biologically?
E.g chemicals in tobacco that are known to promote cancers (carcinogens)
In bradford hill criteria
-Specificity of association
-A cause leads to a single effect. However, a single cause often leads to multiple effects. Exposure-Outcomes are usually not 1:1. E.g smoking leads to multiple outcomes.
In bradford hill criteria
-Reversibility
The demonstration that under controlled conditions changing the exposure causes a change in outcome E.g British Dr’s study: reduced risk after quitting
A cause of disease….
An event, condition, characteristic (or combination of these factors) which play an essential role in producing the disease.
KJ Rothmans created the theory of…
Causal pies
Components of the casual pie
- a SUFFICIENT
- a COMPONENT
- a NECESSARY
A sufficient cause in a causal pie is…
a factor/s that will inevitably produce the specific disease. E.g each entire pie
A component cause in a causal pie is…
a factor that contributes towards dis-ease causation, but is not sufficient to cause dis-ease on it’s own. E.g A single component of the casual pie.
A necessary cause in a causal pie is…
a factor (or component cause) that MUST be present if a specific dis-ease is to occur. E.g the component in all of the causal pies.
TB reduction resulted as…
There was an improvement of living standards… Causes of TB was poverty, poor sanitation, overcrowding, reduced immunity. Slight increase in death rate when chemotherapy was found due to the weakening of immunity this brings. Otherwise, a vaccine further helped reduce deaths from this disease.
Intervene in causal pie
We can intervene at any number of points in the pie to prevent disease.
Preventive measures
Knowledge of the complete pathway is not a pre-requisite for introducing preventive measures.
Epidemiology can play an essential role in preventing disease/injury by:
- unravelling the causal pathway
- directing preventive action
- evaluation of effectiveness
Why is the need for disease preventions growing?
- apparent limitations in treating disease
- cost of medical care is increasing
intervention designs in population health are…
trying to improve well being of individuals of populations or identify early stages of disease, reduce number of patient load in order to let those who need the intensive treatment to benefit.
What are the three population health actions?
- health promotion
- disease prevention
- health prevention
Population based (mass) strategy focus
focuses on the whole population in order to reduce the risk factors/ improve the outcome of all individuals in the population.
Why is population based strategy useful?
-useful for a common disease or widespread cause
Examples of population based strategy
immunisation, water fluoridation, legislation of seat belts
Define high risk strategy
Stratergies that deal with individuals that are at high risks and try to shift those with high risk towards the rest of the population.
Examples of high risk stratergies
Intervention targeting obese adults, intravenous drug users (reduce HIV amongst drug users).
The type of intervention for high risk strategies
the intervention is well defined to the persons needs.
High risk individual strategy: NZ needle exchange programme
Target: to reduce the amount of HIV within the population of injecting drug users.
Involved exchanging a used needle for a new one.
advantages and disadvantages of population mass stratergy
advantages: 1. addresses underlying causes
2. large potential benefit for whole population (Vaccine of TB)
3. Behaviourally appropriate (smokers on airplanes)
disadvantages: 1. small benefit to individuals
2. poor motivation of individuals (as may not apply to them)
3. whole population is exposed to downside of strategy (less favourable benefit to risk ratio)
Advantages and disadvantages to high-risk individual statergy
advantages: 1. appropriate to individuals
2. individual motivation
3. cost effective use of resources (time and money to group who need it)
4. favourable benefit-to-risk ratio (targeted strategy benefits outrules down sides).
disadvantage: 1. cost of screening, need to identify individuals.
2. Temporary effect (screening is an ongoing process)
3. Limited potential (screenings on women over 40 for down syndrome babies but more is seen in women under 40 who do not receive screening)
4. Behaviourally inappropriate- hard to move away from cultural norms.
Health promotion, Acts, focus, enables, involves who?
- Acts on determinants of wellbeing
- health/well being focus
- Enables/empowers people to increase control over, and improve, their health.
- Involves whole population in everyday context.
Examples of health promotion
E.g 5 plus a day and push play
Types of care and what they are defined as…
Primary care- Patients regular source of health care e.g GP, pharmacist
Secondary care- Referred to by primary care service e.g neurologist
tertiary care- institutional care services e.g hospitals
Prerequisite of health according to Alma Ata 1978- the ottawa charter
peace and safety from violence, shelter, education, food, income and economic support, stable ecosystem and sustainable resources, social justice
Alma Ata 1978 job
- protect and promote health of all
2. advocated a health promotion approach to primary health.
