Public Health Peer Teaching Flashcards
What are the 3 domains of Public Health?
- Health improvement
- Health protection
- Improving services
Give examples of ‘Health improvement’ as applied to Public Health
- Inequalities
- Education
- Housing
- Employment
- Lifestyles
- Family / community
Give examples of ‘Health Protection’ as applied to Public Health
- Infectious disease
- Chemicals and poisons
- Radiation
- Emergency response
- Environmental health hazards
Give examples of ‘Improving services’ as applied to Public Health
- Clinical effectiveness
- Efficiency
- Service planning
- Audit + evaluation
- Clinical governance
- Equity
What influences health inequalities?
‘PROGRESS’
- Place of residence (rural, urban)
- Race (or ethnicity
- Occupation
- Gender
- Religion
- Education
- Socioeconomic status
- Social capital or resources
What is the difference between equality and equity?
Equity: giving everyone what they need to be successful
Equality: treating everyone the same
What is ‘Horizontal Equity’?
Give an example.
‘equal treatment for equal need’
-> all people with pneumonia deserve equal treatment, all else being equal
What is ‘Vertical Equity’?
Give an example.
‘unequal treatment for unequal need’
- > individuals with pneumonia deserve different treatment from those with common cold.
- > areas with poorer health may need higher expenditure on health services
What is a cohort study?
- Longitudinal study in similar groups but with different risk factors / treatments
- > follows up over time
List 3 advantages of a cohort study.
- can follow up rare exposure
- allows identification of risk factors
- data on confounders is collected prospectively.
List 4 disadvantages of a cohort study.
- Large sample size required
- Impractical for rare diseases
- Expensive
- People drop out
What is a case control study?
- Observational study looking at cause of a disease
- compares similar participants with disease and controls without
- Looks retrospectively for exposure / cause
List 2 advantages of a case control study.
- Quick
- Good for rare outcomes
List 2 disadvantages of a case control study.
- Difficult finding appropriately matched controls
- Prone to selection and information bias
What is a cross sectional study?
- Observational study collecting data from a population at a specific point in time
- A snapshot of a group
List 4 advantages of a cross sectional study.
- Large sample size
- Provides data on prevalence of risk factors and disease
- Quick to carry out
- Repeated studies show changes over time
List 3 disadvantages of a cross sectional study.
- Risk of reverse causality -> which came first?!
- Less likely to include those who recover quickly or short recovery.
- Not useful for rare outcomes.
What is a randomised control trial?
Similar participants are randomly assigned to an intervention or control group to study the effect of the intervention.
List 2 advantages of an RCT.
- Low risk of bias and confounding
- Comparative
List 3 disadvantages of an RCT.
- Hight soup out rate, little incentive to stay in control group arm
- Ethical issues
- Time consuming and expensive
- Prior knowledge required
Define ‘incidence’.
Number of new cases in a population during a specific time period.
Define ‘prevalence’.
Number of existing cases at a specific point in time.
Over a 10 year period, there were 50 new cases of lung cancer in Crookes (a population of 1,000 people). What is the incidence of lung cancer over those 10 years?
50/1000 = 5%
In Crookes (population of 1000 people), 300 people smoke. Of those who smoke, 45 developed lung cancer. 5 of the non-smokers developed lung cancer. What is the relative risk of lung cancer in smokers?
Risk of lung cancer in smokers = 45 / 300 = 15%
Risk of lung cancer in non-smokers = 5/700 = 0.7%
Relative risk (ratio) = 15/0.7 = 21.4
So: 21.4 times more likely to develop lung cancer if a smoker.
Explain ‘attributable risk’ as applied to smoking + lung cancer.
Attributable risk = amount of lung cancer that is specifically due to smoking.
Subtract the ‘naturally occurring’ cases that ‘would have happened anyway’ from the number of cases in the exposed.
Risk of lung cancer in smokers = 15%
Risk of lung cancer in non-smokers = 0.7%
Calculate the attributable risk (risk difference).
15% - 0.7% = 14.3%
Attributable risk = 14.3%
In Crookes (population of 1000 people), 300 people smoke. Of those who smoke, 45 developed lung cancer. 5 of the non-smokers developed lung cancer.
The attributable risk is 0.143.
Calculate the number of people who would have to give up smoking to prevent one death from lung cancer.
Attributable risk = 0.143
NNT = 1/Attributable risk
= 1 / 0.143 = 6.99
=> If 7 people gave up smoking in this population, you would prevent one death from lung cancer.
*always round up a ‘number needed to treat’, as you can’t treat a fraction of a person.
Define ‘sensitivity’.
The percentage of people correctly identified with the disease
Define ‘specificity’.
The percentage of people correctly excluded as ‘disease free’.
What problem might arise if a test is 100% sensitive?
Correctly identifies everyone with the disease as having the disease, but may cause false positives.
What problem might arise if a test is 100% specific?
Correctly excludes everyone without the disease, but may miss people who do have the disease.
What is the ‘Positive predictive value’?
%age of those with a positive test who actually have the disease
What is the ‘Negative Predictive Value’?
%age of those with a negative test who are actually disease free
What is the criteria for a screening test?
- Important disease
- Natural history of the disease must be understood (detectable risk factors, disease markers)
- Simple, safe, precise and validated test
- Acceptable to the population
- Effective treatment from early detection with better outcomes than late detection
- Policy of who should receive treatment.
What can association be due to?
- Bias
- Chance
- Confounding
- Reverse causality
- True association
Analytical methods may confirm an association between an exposure and an outcome. How can causality be confirmed following this?
Causality can only be confirmed if alternative explanations are accounted for.
What is ‘bias’?
A systematic error that results in a deviation from the true effect of an exposure of an outcome.
What is ‘chance’?
The possibility that there is a random error
What is ‘reverse causality’?
Outcome results in exposure.
What are the 3 types of bias?
- Selection bias
- Information bias
- Publication bias
Explain ‘selection bias’.
- Non-response of certain groups
- Allocation bias -> different participants in different groups
Explain ‘information bias’.
- Measurement bias
- Observation bias
- Recall bias (doesn’t remember or recall correctly)
- Reporting bias (don’t report truth because they feel judged)
Explain ‘publication bias’.
Trials with negative results less likely to be published.
What is ‘lead time bias’?
Early identification doesn’t alter outcome but appears to increase survival
-> patient knows they have the disease for longer
What is ‘length time bias’?
A disease that progresses more slowly is more likely to be picked up by screening (i.e. symptom free + around for longer), which makes it appear that screening prolongs life.
What is ‘confounding’?
When an apparent association between an exposure and an outcome is actually the result of another factor.
Example: Study looking at association between occupation and lung cancer could be the result of the occupational cohort more likely to smoke and therefore at increased risk.
What is the Bradford Hill criteria for causation?
- Temporality
- Dose-response
- Strength
- Reversibility
- Consistency
- Plausibility
- Coherence
- Analogy
- Specificity
What is the thinking behind the Bradford Hill criteria for causation?
Bradford Hill listed 9 considerations that are used in epidemiology to build up evidence for a causal relationship.
Describe ‘Strength’ as applied to the Bradford Hill criteria.
The stronger the association between the exposure and outcome, the less likely that the relationship is due to some other factor
Describe ‘dose-response’ as applied to the Bradford Hill criteria.
There is a higher risk of outcome [x] with more exposure to [y].
-> higher exposure leads to higher risk
Describe ‘temporality’ as applied to the Bradford Hill criteria.
Exposure occurs before outcome. eg. people smoke before developing lung cancer
Describe ‘reversibility’ as applied to the Bradford Hill criteria.
If you take away the exposure, then the risk of disease decreases or is eliminated -> stop smoking and you have a decreased risk of lung cancer after 10 years.
Describe ‘consistency’ as applied to the Bradford Hill criteria.
The association is seen in different geographical areas, using different study designs, in different subjects (eg. smoking is associated with lung cancer in dogs, mice and people, all over the world.
-> Repeatability of the result.
What are the stages of the ‘planning cycle’ for Health Services?
- Needs assessment
- Planning
- Implementation
- Evaluation
What are ‘Health Needs Assessments’?
HNA provides a systematic approach to assessing health needs to reduce inequalities in health and inform decision making and action planning to improve health.
How do we define ‘Health’?
- Biomedical: absence of disease
- Psychosocial: stress + function
- Lay views: felt + expressed needs
- > Who defines ‘health’ is the first step in carrying out a Health Needs Assessment.
What are ‘Bradshaw’s Needs’?
- Felt need
- Expressed need
- Normative need
- Comparative need
Define ‘felt need’.
Individual perceptions of variation from normal health.
Define ‘Expressed need’.
Individual seeks help to overcome variation in normal health (demand).
Define ‘Normative need’.
Professional defines intervention appropriate for the expressed need.
Define ‘comparative need’.
Comparison between severity, range of interventions, and cost.
What are the 3 core different ‘approaches’ to a Health Needs Assessment?
- Epidemiological
- Comparative
- Corporate
Explain the ‘Epidemiological’ approach to a Health Needs Assessment.
- Define your issue, assess incidence / prevalence, assess services available, is the effective / cost effective?, assess the care, assess for any unmet need / any unneeded services
What problems might one encounter when using an Epidemiological approach to a Health Needs Assessment?
- Data may not be available / poor quality data
- Doesn’t consider felt needs
- Reinforces biomedical approach
Explain the ‘Comparative’ approach to a Health Needs Assessment.
- Compare the services received by 2 populations / areas
eg. services available, cost effectiveness, assess the care, assess for unmet need.
What problems might one encounter when using a Comparative approach to a Health Needs Assessment?
- Data not available / poor quality data
- Difficulties finding a comparable group
- It’s possible that neither group is using the ideal services
- No assessment against current evidence
What are the advantages of using a Comparative approach to the Health needs assessment?
- Quick
- Cheap
- Can measure variation
Explain the ‘Corporate’ approach to a Health Needs Assessment.
- Collect the views of the ‘stake holders’ eg. patients / service users / GPs
- Ask them what they think is needed.
What are the problems associated with a ‘Corporate’ approach to a Health needs assessment?
- Blurs the difference between need and demand
- Vulnerable to influence by political and personal view.s.
List 8 models of behaviour change.
- Health Belief Model
- Theory of Planned Behaviour
- Stages of Change / Transtheoretical Model
- Social Norms theory
- Motivational Interviewing
- Social marketing
- Nudging
- Financial incentives
Explain the concept of the ‘Health Belief Model’.
To increase the chance of an individual change a health behaviour, you need to influence how they perceive 4 factors:
- susceptibility to ill health
- severity of ill health
- benefits of behaviour change
- barriers to taking action
What are the 4 factors which are considered in the Health Belief model?
How does a patient perceive the following:
- susceptibility to ill health
- severity of ill health
- benefits of behaviour change
- barriers to taking action
Explain the Health Belief Model as applied to smoking cessation.
Pt perceives:
- that they could get lung cancer
- that lung cancer is bad for them
- that by stopping smoking they will reduce their risk of lung cancer / cough less
- that there are smoking cessation services to help them remove the barriers
What are the principles behind the ‘Stages of Change’ / ‘Transtheoretical Model’ of behaviour change?
- There are 5 core stages of behaviour change
- There’s fluid movement between these stages
- You work your way along the steps at your own pace, but at any point a relapse may send you back to the start.
What are the 5 core stages of the ‘Stages of Change’ / ‘Transtheoretical Model’ of behaviour change?
- Pre-contemplation
- Contemplation
- Preparation
- Action
- Maintenance
Apply the ‘Stages of Change’ / ‘Transtheoretical Model’ to smoking cessation.
- Pre-contemplation: not considered quitting
- Contemplation: thinking about quitting
- Preparation: buying NRT patches, setting quit date
- Action: Quitting
- Maintenance: Remaining a non-smoker
Explain the principles behind the theory of planned behaviour
Different factors come together to give a person the intention to change, and once they decide to change, they will
-> puts everything on the idea of ‘planned behaviour’ being the actually behaviour
What 3 things contribute to the intention for the theory of planned behaviour?
- Attitudes
- Subjective norm
- Perceived behavioural control
Explain ‘attitude’ as a component of the theory of planned behaviour model.
-> the belief that smoking is bad for you, therefore you will stop
Explain ‘subjective norm’ as a component of the theory of planned behaviour model.
The difference between thinking ‘everyone smokes’ to ‘actually, not many people smoke’.
Explain ‘Perceived behavioural control’ as a component of the theory of planned behaviour model.
-> pt thinks that they are in control of their smoking, and that if they want to quit, they will be able to.
What are the features of a Communicable Disease that would make it a Public Health concern?
- High mortality
- High morbidity
- Highly contagious
- Expensive to treat
- Effective interventions
Who should be notified of a Notifiable disease?
- Registered Medical Practitioners
- Labs
- PHE
When should a notifiable disease be notified?
- Any case of a notifiable disease -> on clinical suspicion (not lab confirmation)
- Any other infection / contamination that could risk human health
What details should you explain if you have a patient with a notifiable disease?
- Case details: NHS No., DOB, Contact details
- Details of the disease / contamination
How should you notify the presence of a Notifiable disease?
- Contact local health protection authority / PHE
- Written notification or telephone, if urgent
List the notifiable diseases beginning with ‘A’.
- Acute encephalitis
- Acute infectious hepatitis
- Acute meningitis
- Acute poliomyelitis
- Anthrax
List the notifiable diseases beginning with ‘B’, ‘C’, ‘D’, ‘E’ and ‘F’.
- Botulism
- Brucellosis
- Cholera
- Diphtheria
- Enteric fever (typhoid or paratyphoid fever)
- Food poisoning
List the notifiable diseases beginning with H, I, or L
- Haemolytic Uraemia Syndrome (HUS)
- Infectious blood diarrhoea
- Invasive Group A Streptococcal Disease
- Legionnaire’s disease
- Leprosy
