SocPop and VLE Flashcards
What factors can shape people’s health beliefs?
Structural location
Cultural context
Personal biography
Social identify
What are lay health beliefs?
Perspectives of ordinary people, distinguishable from theoretical or professional perspectives
How non-expert people understand and experience health
People draw on a range of knowledge and experience
People hold complex and sophisticated beliefs about causation of disease and health maintenance
Why are lay beliefs important to you as doctors?
Insights into needs of patients: information and support
Influence health seeking behaviour:
How people respond to symptoms, Decisions about consulting, Expectations about treatment, Concordance with treatment plans
What is a symptom iceberg?
Proportion above water represents those symptoms that are actually presented to a health care proportion 1/3
Portion below water are 2/3 people who do nothing about their symptoms, self medicate, or seek alternative help
What are the 3 parts to help seeking behaviour that determines patients decision to consult?
Perception of symptoms - severity, frequency, familiarity, duration
Explanation of symptoms - how they make sense of them in context of their lives – linked to beliefs, knowledge and experience
Evaluation of symptoms - costs and benefits of seeking help
What are social triggers to seeking medical help?
Interference with social and personal relationships
Interference with vocational or physical activity
Sanctioning by others – influence of lay referral system
Temporalising of symptoms - set deadlines when go on for long time
Interpersonal crisis - other things going on simultaneously
What are 3 types of health behaviour?
Good health behaviours: Sleeping 7-8 hours, regular exercise, healthy eating, eating breakfast every day
Health protective behaviours: Wearing a seatbelt, attending regular check-ups, health screening
Health impairing habits: Smoking, eating a high fat diet, alcohol abuse
What is the dual pathway model?
Two broad ways in which psychological processes may influence physical health
Direct pathway - eg stress has direct impact on health
Indirect - psychology affects behaviour which in turn can affect health
Eg when stressed, may smoke more or eat more chocolate
What is the biopsychosocial model of health?
Integrates 3 core areas which interact to influence health
Biology - microbes, genetics
Psychology - Behaviour, Emotions, Beliefs, Coping, Stress
Social - class, employment, ethnicity
What are determinants of health behaviour?
Background factors: Characteristics that define how people live their lives
Stable factors: Individual differences (personality) in psychological activity that are stable over time and context
Social factors: Social connections in the immediate environment
Situational factors: Appraisal of personal relevance that shape responses in a specific situation
How do stable factors affect health behaviour?
Individual differences and personality
Sensitivity towards types of event
Understanding and evaluating the event, e.g. as threat or challenge
Suggest, potential responses, i.e. initial response options
What are the 3 broad types of individual differences that affect health behaviour?
Emotional dispositions: Experience and expression, present
Generalised expectancies: Psychological processes involved in formulating expectations in relation to future outcomes
Explanatory styles: Psychological processes involved in explaining the causes of negative events, past
What are the emotional dispositions-five personality traits?
OCEAN
Openness to new experiences - Intellect and interest in culture; artistic,
curious, imaginative, wide range of interest
Conscientiousness - The will to achieve; self disciplined, efficient, organised, reliable, thorough
Extroversion - Outgoing; talkative, enthusiastic, seeking excitement, assertive and active
Agreeableness - Loving, friendly and compliant; sympathetic, appreciative, trusting, kind, forgiving, generous
Neuroticism - Experience more negative emotions; anxious, tense, worried, hostile, self-pitying, vulnerable
Which personality trait might make a person more likely to engage in positive health behaviours?
Conscientiousness
Which personality trait might make a person less likely to engage in negative health behaviours?
Neuroticism
What is a locus of control?
Expectations that future outcomes will be determined by factors that are either internal (self) or external (powerful others, and chance)
Which locus of control is associated with positive health outcomes?
Internal LOC associated with more favourable outcomes and performance of health behaviours, but dependent on situational factors
People with an internal locus of control believe they are responsible for their own health, Illness can be avoided by taking care of themselves, ill health results from not eating correctly or not getting enough exercise
What are 2 types of generalised expectancies?
Locus of control
Self efficacy
What is self efficacy?
Belief in one’s own ability to organise and execute a course of action, and the expectation that the action will result in a desired outcome
What are 2 types of explanatory styles?
Optimism/ Pessimism - Expectation of positive future outcome despite current negative event, Low levels of physiological reactivity in mild and moderate stress, promotes active coping responses
Optimism associated with better physical health, illness recovery, and health behaviour performance
Attributional style - Causal explanations of negative events as internal (self), permanent (time), and global (situation)
Generally better if attributions are specific, rather than internal (guilt),
permanent and global. Causal attributions influence expectations about future outcomes, i.e. the relevance of health behaviours
What are the social cognition theories?
Health belief model - susceptibility, severity (threat) barriers, benefits (efficacy)
Theory of planned behaviour - Behavioural beliefs, Outcome evaluation, (attitude) Normative beliefs, Motivation to comply (subjective norm) Control beliefs, Self-efficacy (perceived behavioural control)
Stages of change/transtheorectical model - pre contemplation, contemplation, planning, action, maintenance, relapse, stages improve with self efficacy and decrease with temptation
What is epidemiology?
Study of disease in populations
What is a mortality rate?
Number of people dying in a defined population in a defined period of time
What are 2 concepts of causality?
Deterministic Approach - inevitability, Validation of hypothesis by systematic observations to predict with certainty future events. A causes B eg Tubercle bacillus is the cause of tuberculosis. Mechanistic, can take apart to study, Objective, quantifiable, certain, Whole is the sum of the parts, single cause for a single disease
Stochastic Approach - probability, Assessment of hypothesis by systematic observations to give risk of future events. If you have A, probability of getting B is… Eg Tuberculosis is more
common in overcrowded accommodation. Whole greater than sum of
parts, Whole not predictable from knowledge of parts, Probabilities, Systems theory; complexity theory, The observer influences the observed, Emergent phenomena, useful for studying processes of ageing, chronic disease
What is a confounding variable?
Something that is associated with both the exposure and the outcome
Eg smoking would be a confounding factor in a study of obesity and heart disease
An exposure is independently associated with the outcome after taking confounding factors into account
What is a mediating variable?
A mediator is variable through which an exposure wholly or partially exerts its effect
Eg sugar excess leads to obesity which in turn leads to heart disease
Obesity is a mediating variable
What is reverse causality?
Unemployment can lead to mental illness
Mental illness can lead to unemployment
Describe Bradford Hill’s Criteria for Inferring Causality
Association factors - Strength of association, Specificity, Consistency
Exposure/outcome - Temporal sequence, Dose response, Reversibility
Other evidence - coherence of theory, biological plausibility, analogy
Describe strength of association
A causal link is more likely with strong associations (measured by rate ratio or odds ratio)
e.g. Heavy smokers have 20 times risk of mortality from laryngeal cancer than non-smokers
But weak associations can still be causal, e.g. environmental tobacco smoke and ischaemic heart disease
Strong associations are unlikely to be explained by undetected confounding or bias however, this is not always true, e.g. Popper’s and Kaposis’ sarcoma (OR=8.5) thought causal prior to discovery of HIV
Describe specificity of association
A causal link is more likely when a disease is associated with one specific factor and vice-versa
Eg Asbestos causing Mesothelioma
However, lack of specificity does not necessarily weaken the case, e.g. tobacco smoking causing many cancers and diseases
current models of disease causation are multi-factorial
Describe consistency of association
A causal link is more likely if the association is observed in different studies and different sub-groups
Consistency of association between studies or groups is unlikely to be due to the same confounding or bias
Lack of consistency can be due to features of study design
Eg: Many different studies demonstrated the association between smoking and ischaemic heart disease
Describe temporal sequence in terms of causality
A causal link is more likely if exposure to the putative cause has been shown to precede the outcome
The corollary is that a causal link cannot exist if the outcome preceded exposure to the putative factor
Optimal study designs - RCTs, cohort study
Weak study designs - cross-sectional (prevalence), case-control study
Describe dose response in terms of causality
A causal link is more likely if different levels of exposure to the putative factor lead to different risk of acquiring the outcome
Dose response (biological gradient) is unlikely to be due to unknown confounding or bias
lack of a biological gradient does not rule out a causal link, e.g.
threshold effect, J-shaped or U-shaped relationship
Describe reversibility in terms of causality
A causal link is very likely if removal or prevention of the putative factor leads to a reduced or non-existent risk of acquiring the outcome
Probably strongest evidence for causal link but difficult to demonstrate
many disease have long time lags, e.g. mesothelioma takes 20-40 years to develop following exposure to asbestos
ethical issues for a RCT of a prevention programme, e.g. smoking cessation. public health programme to remove or prevent an exposure
often requires action by society
Describe coherence of theory in terms of causality
A causal link is more likely if the observed association conforms with current knowledge
Coherence with current paradigms/constructs/theories strengthens case for a causal link
however, this leads to inappropriate rejection of ‘unfavoured’
associations, i.e. ‘publication bias’ towards studies that support
favoured theories or demonstrate that drug / interventions work
lack of coherence does not rule out a causal link, e.g. Helicobacter
pylori and peptic ulcers
Example of coherence of theory: The link between socio-economic deprivation and lower life expectancy is now well established
Describe biological plausibility in terms of causality
A causal link is more likely if a biologically plausible mechanism is likely or demonstrated
Describe analogy in terms of causality
A causal link is more likely if an analogy exists with other diseases, species or settings
An analogy is easier to infer than a biologically plausible mechanism
Eg - The epidemiology of Hepatitis B virus was successfully used to predict how HIV virus would spread
What is a cross sectional survey?
Observational study
Investigate distribution of a specific disease in population
Monitoring health over time
Medium cost
Usually max 50% response rate
Information is collected from each subject in the study population at one point in time
To determine the prevalence of something (descriptive)
To investigate possible associations between exposures and a particular outcome (analytic)
What is a case control study?
Observation study
Investigate suspected determinants eg Outbreak investigation and determinants of rare conditions
Quick and Cheap
Recall and selection bias an issue
Case control studies involve comparing subjects with a condition (the cases) to subjects without the condition (the controls)
The level of exposure to a factor or factors is determined for both groups and compared. If the prevalence of exposure is higher in cases than in controls then the exposure might be a risk factor
What is a cohort study?
May be set up for a specific purpose, more often multipurpose Eg effects of smoking, asbestos
Determinants of common conditions
Relative importance of different factors
(Very) slow and (very) expensive
Issues due to confounding with unknown risk factors
What are uncontrolled studies?
Easy to do
Selection bias a problem
Don’t know what happens without intervention
What is the hierarchy of evidence?
Systematic reviews
Experimental studies - Randomised Controlled Trials, Controlled trials
Observational studies - Cohort studies, Case control studies
Descriptive studies - Cross sectional
(Qualitative studies)
What is bias?
Any trend in the collection, analysis, interpretation, publication of review of data that can lead to conclusions, that are systematically different from the truth
What types of bias can be present in epidemiological studies?
Selection - Admission, prevalence/incidence, detection, volunteer, loss to follow up
Information - Interviewer, questionnaire, recall, diagnostic suspicion and exposer
Confounding
What are issues with epidemiological studies?
Epidemiological studies provide information on average effects
These averages hide individual level variation
For some patients it will be better not to do what is best on average
If patients have strong preferences for treatments it is likely to be best to support these preferences
When are epidemiological studies best?
Single agent causes single disease or single treatment reverses disease
are very good when: Primary factor causes specific disease with
several secondary influences
are more limited when: Many different factors interact with each other in complex pathways to create the conditions in which multiple diseases are likely to arise
What are objectives of epidemiological studies?
Investigate disease aetiology - exposure → outcome relationship interested in causal understanding
Identify risk factors or protective effects - quantified in some way, absolute / relative risk (or protective effect)
Evaluate health needs / disease / treatment and prevention strategies
What are analytical studies?
Cohort studies
Case control studies
Cross sectional studies
Describe the types of epidemiological studies
Descriptive studies - Examine patterns of disease
Analytical studies - Studies of suspected causes of diseases
Experimental studies - Compare treatment modalities
What is an ecological study?
Compares an area or population with another
e.g. the amount of alcohol drunk in France and UK and rates of cirrhosis in each country; the amount of saturated fats and rates of CVD across countries (Seven Countries Study)
Easy to do as use available information
Work on whole population data - cannot necessarily apply to
individual person
What is ecological fallacy?
Ecological inference - a conclusion about individual behavior drawn from data about aggregate behavior
The “ecological fallacy” consists in thinking that relationships observed for populations hold for individuals: if countries with more Protestants tend to have higher suicide rates, then Protestants must be more likely to commit suicide
What are advantages and disadvantages of ecological studies?
Advantages: Relatively cheap and simple to do, May raise hypothesis
Disadvantages: Can’t establish causation - only association, Ecological fallacy, Many of the disadvantages of cross sectional studies – with
less reliable data collection! Confounding
What are advantages and disadvantages of cross sectional studies?
Advantages: Relatively cheap and simple to do, Good for examining exposures that do not change over time (e.g. sex), No exposure to harm or denial of beneficial therapy (“ethically safe”), May raise hypothesis
Disadvantages: Can’t establish causation - only association, Cannot measure incidence, Confounding, Recall bias, Response rates
Why do we need case-control studies?
Conventional cohort studies take a long time
Cohort studies are expensive – especially if you need detailed information
Cohort studies are not good for studying rare events (disease) because they need to be impossibly large
What is the odds ratio?
(Exposed cases / non exposed cases) /
exposed controls / non exposed controls
What is incidence rate ratio?
(Exposed cases / total exposed) /
(Unexposed cases / total unexposed)
Incidence in exposed / incidence in unexposed
When is Odds Ratio as a good approximation of theIncidence Rate Ratio in the population?
The disease is not common (“rare disease assumption”)
The cases are representative, with regard to the exposure, of all
people with the disease in the population
The controls are representative, with regard to the exposure, of all people without the disease in the population
What is the error factor?
Exp ( 1.96 x root of 1/exposed cases, 1/exposed controls, 1/non exposed cases, 1/non exposed controls)
What is the 95% confidence interval for the odds ratio?
(OR / error factor) to (OR x error factor)
How do you decide how many controls are required in the study?
Precision of an OR is affected by the number of controls
So, it is worth increasing the number of controls – up to a point, typically up to 4-6 times as many controls as there are cases
Describe the difference between Conventional vs. nested case-control studies
Conventional case-control study: retrospective collection of data (from recall)
Nested case-control study: nested within a cohort study, collection of data before disease has developed (from pre-existing records or biological samples)
Advantages over conventional case-control studies: incidence rates can be calculated (sampling fractions known) population for sampling of controls is already defined data obtained before disease has developed, thus recall bias is eliminated
Advantages over conventional cohort studies: can collect more detailed information for a minority of participants, costs dramatically reduced
it is a cost-effective alternative to a full cohort analysis
What are advantages and disadvantages of case control studies?
Advantages: relatively quick & cheap, no loss to follow up, Multiple exposures can be examined, Rare diseases and diseases with
long latency can be studied, Suitable when randomisation is unethical (alcohol and pregnancy outcome)
Disadvantages: prone to biases (e.g. recall), problems sorting out sequence of events, not suitable for rare exposures, cannot measure disease incidence, Multiple outcomes cannot be studied
What is a cohort study?
A cohort is a group of people who have something in common eg Worked in the same industry, Take the same drug
A cohort study is one in which a group of people are followed up over time
Two groups of people, one group exposed and another unexposed to a potential cause of disease, followed-up over time and the incidence of the disease in one group is compared with the incidence in the other
What can cohort studies be used to look at?
Disease Aetiology - What happens to people who have been exposed to an agent or problem? do they die or get ill earlier than other people?
if so, what from? by how much does exposure increase risk, how much exposure is needed
Disease Prognosis: What factors predict survival in people with a disease or health problem? risk and protective factors, benefits of treatment
