PUBLIC HEALTH Flashcards
What are the three domains of public health?
Health improvement
Health protection
health services
What is horizontal equity?
Equal treatment for equal need
What is vertical equity?
Unequal treatment for unequal need
What is a health need?
Ability to benefit from an intervention
What are Bradshaw’s needs?
Felt
Expressed
Normative
Comparative
FENC
What are the three ways to assess health needs?
Epidemiological
Comparative
Corporate
What are the advantages/disadvantages of using an epidemiological approach to health needs assessment?
‘Top-down’ approach.
Uses existing data.
Quality of data can be variable.
Doesn’t consider felt needs.
What are the advantages/disadvantages of using a comparative approach to health needs assessment?
Compare health provision of one population to another.
Can be spacial (town/city) or social (class).
Cheap, indicates where comparative need is greatest.
Doesn’t identify level of ‘good’ provision.
What is a corporate approach to health needs assessment?
Ask the local population what their health needs are.
Focus groups, public meetings and interviews.
Wide variety of stake-holders e.g. politicians, teachers, charities.
What are the two approaches to health needs evaluation?
Maxwell’s
Donabedian
What is Maxwell’s approach to health needs evaluation?
3 E’s:
Equity
Effectiveness
Efficiency
3 A’s:
Appropriateness
Accessibility
Acceptability
Describe the donabedian approach to health needs evaluation
Structure
Process
Outcome
What are the Wilson and Juggler criteria for a good screening test?
Is the condition important?
Is there an accepted treatment?
Facilities for diagnosis and treatment should be available.
There is should be a recognizable latent or early phase.
There should be a suitable test or examination.
The test should be acceptable to the population.
The natural history of the condition should be adequately understood.
What is sensitivity?
Sensitivity: percentage of those with the disease who have positive tests.
What is specificity?
Specificity: percentage of those without the disease who have negative tests.
What is the positive predicted value?
Positive predicted value (PPV): the percentage of correct positive results.
What is the negative predicted value?
Negative predicted value (NPV): the percentage of correct negative results.
Describe two types of bias that can be seen in screening
Lead time bias
Length time bias
What is lead time bias?
When screening identifies an outcome earlier than it would otherwise have been identified this results in an apparent increase in survival time, even if screening has no effect on outcome.
What is length time bias?
Type of bias resulting from differences in the length of time taken for a condition to progress to severe effects, that may affect the apparent efficacy of a screening method.
What is incidence?
Incidence: rate at which new cases appear (must give time frame).
What is the prevalence?
Prevalence: number of cases at any given time (%).
What is the absolute risk?
Percentage of people who get the disease, regardless of the risk factors
What is the relative risk?
People with the disease who have risk factors compared to people with the disease who do not have risk factors
e.g. percentage of smokers with lung cancer / percentage of non-smokers with lung cancer
What is attributable risk?
The difference in risk between those who are exposed to risk factors and those who are not
e.g. Percentage of smokers who develop lung cancer - percentage of non-smokers who develop lung cancer
What is the number needed to treat?
1/attributable risk
What are the advantages/disadvantages of case-control studies?
Advantages:
- Good for rare outcomes (e.g. cancer)
- Quicker than cohort or intervention studies (as the outcome has already happened)
- Can investigate multiple exposures
Disadvantages:
- Difficulties finding controls to match with cases
- Prone to selection and information bias
What are the advantages and disadvantages of cohort studies?
Advantages
- Can follow-up a group with a rare exposure (e.g. a natural disaster)
- Good for common and multiple outcomes
- Less risk of selection and recall bias
Disadvantages
- Takes a long time
- Loss to follow up (people drop out)
- Need a large sample size
What are the advantages and disadvantages of RCTs?
Advantages:
- Low risk of bias and confounding
- Can infer causality (gold standard)
Disadvantages:
- Time consuming
- Expensive
- Specific inclusion/exclusion criteria may mean the study population is different from typical patients (e.g. excluding very elderly people)
Name three types of association bias
Selection bias
Information bias
Publication bias
What is a confounding factor?
Both the exposure and the outcome are affected by another factor.
What is reverse causality?
Outcome causes the exposure e.g. depression and obesity
What is information bias?
source of information is bias e.g. observer, participant (recall bias) or measurement (faulty equipment)
What are the Bradford-Hill criteria for causation?
9 conditions that increase the likelihood of causation:
- Temporality – exposure occurs prior to outcome.
- Dose-response – increase exposure = increased outcome.
- Strength – strong association between exposure and outcome (high risk).
- Reversibility – intervention reducing exposure, reduces outcome.
- Consistency – same result from various settings.
- Biological plausibility – can be explained using existing biological knowledge.
- Coherence – coheres with other study findings.
- Analogy – similar effects found in other cause/effect relationships.
- Specificity –the exposure leads to the outcome more than other factors.
What is health behaviour?
Staying health e.g. exercise
What is illness behaviour?
Seeking help e.g. going to the GP
What is a sick–role?
Getting better e.g. taking abx
Name three ways in which health intervention can be delivered
Individual level
Community level
Population level
Name three models of behaviour change
health belief
theory of planned behaviour
transtheoretical model
What are the key components of the health belief model of behaviour change?
Believe you are susceptible to disease
Believe the disease is serious
Believe in taking action
Believe benefits outweigh the costs
What are the stages of the transtheoretical model of behaviour change?
Pre-contemplation
Contemplation
Preparation
Action
Maintenance
Relapse
How do you calculate the units of alcohol in a drink?
Units = ABV (%) x volume (mls) / 1000
Name two models of error
Three-bucket model
Swiss cheese model
Describe the three bucket model of error
Self, context, task
What is compliance?
Compliance is the extent to which a patient’s behaviour coincides with medical or health advice. It is professionally focused rather than patient focused and assumes doctors know best. It does not look at problems patients have in managing their health/illness.
What is adherence?
Adherence acknowledges the importance of patients’ belief. It regards the health professional as the expert conveying their knowledge which results in enhanced patient knowledge, satisfaction and adherence to the recommended medical regime.
What is concordance?
Concordance thinks of patients as equals in care. It is expected that they will take part in treatment decisions. The consultation is now a negotiation between equals.
What is the number needed to harm?
1/absolute risk difference
What is the odds of an event?
the ratio of the probability of an occurrence compared to the probability of a non-occurrence.
Odds = probability/(1-probability)
What is the odds ratio?
The odds ratio is the ratio of odds for exposed group to the odds for the not exposed groups.
OR = {Pexposed/ (1 – Pexposed)}
{Punexposed/ (1 – Punexposed)}
What is statistical analysis using per protocol?
• Only includes the participants that fully completed the intervention and the
full follow up
What is statistical analysis using intention to treat?
All participants that were initially enrolled, even those who were then lost to follow up
What is a null hypothesis?
No statistically significant difference between two groups or populations and
any observed difference is due to error
What is an alternative hypothesis?
• Statistically significant difference between two groups or populations
What is the p-value?
- Probability of outcome occurring by chance.
* If the p value is less than .05, the observed result is said to be statistically significant.
What is a confidence interval?
• Range within which the true size of the effect lies within a given assurance • If include 0 the effect is considered to be insignificant
