Public Heath Flashcards
Causes of associations
Bias Chance Confounding Reverse causality True association
Define bias?
Selection bias?
Types of information bias? (4)
Publication bias?
Definition: A systematic error that results in a deviation from the true effect of an exposure on an outcome
Selection bias- Selection of study population eg. Non response of certain groups, loss to follow up of certain groups
Allocation bias e.g. different participants in the groups
Information bias (MORR) -
Measurement bias (different equipment measures things differently)
Observer bias- Observer’s expectations influence reporting
Recall bias- Past events not remembered or recalled correctly
Reporting bias- Respondent doesn’t report the truth because they feel ashamed/judged
Publication bias- Trials with negative results less likely to be published
Drug trials more likely to be published if sponsored by drug company
What are the brad ford hill criteria for causation ?
STD R Crap
Strength - very high relative risk (Relative Risk of 21)
Temporality - most important - exposure occurs before outcome (people smoke before developing lung cancer
Dose-response - more risk of outcome with more exposure (the more you smoke the higher the risk of lung cancer)
Reversibility - 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 or so)
Consistency - the association is seen in different geographical areas, using different study designs, in different subjects (smoking is associated with lung cancer in dogs, mice and people, all over the world)
2 pros and 2 cons of RCT ? What is it/>
😍 Low risk of bias and confounding
😍 Can infer causality
😒 Time consuming and expensive
😒 Unrepresentative study population
Similar participant are randomly assigned to an intervention or control group
Case control basics? 2 pros 2 cons?
Observational study looking at cause of a disease. Compares similar participants with disease and controls without.
Looks retrospectively for exposure/cause
😍 Quick (as outcome has already happened)
😍 Good for rare outcomes (e.g. cancer)
😒 Difficult finding appropriately matched controls
😒 Prone to selection and information bias
Cross sectional basics? 2 pros / cons?
Observational study collecting data from a population and a specific point in time.
A snapshot of a group e.g. census or patient survey
😍 Large sample size
😍 Provides data on prevalence
😒 Risk of reverse causality- which came first?
What is reverse causality?
Outcome may have caused the exposure
Eg survey on whether depressed people are obese -which caused which
Cohort basics? Pros? Cons?
Longitudinal study in similar groups but with different risk factors/treatments. Follows them up over time
E.g. Framingham Heart Study or smoking doctors vs non-smoking doctors
😍 Can follow up rare exposure e.g. natural disaster
😍 Allow identification of risk factors (exposure causing outcome)
😒 Takes a long time, people drop out
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Over a ten year period, there were 50 cases of lung cancer in Crookes (a population of 1,000 people).
What is the incidence (risk) of lung cancer per year?
(50/1000)/10 = 0.5%/ year
In Crookes (a population of 1000 people), 300 of them smoke. Of those who do smoke, 45 of them developed lung cancer. 5 of the non-smokers developed lung cancer. What is the relative risk of lung cancer in smokers?
Risk in exposed = 45/300 = 15%
Risk in unexposed = 5/700 = 0.7%
Relative risk (risk ratio) = 15/0.7 = 21.4 times more likely to develop lung cancer if you smoke compared to non smokers
In Crookes (a population of 1000 people), 300 of them smoke. Of those who do smoke, 45 of them developed lung cancer. 5 of the non-smokers developed lung cancer. What is the risk of lung cancer that is attributable to smoking?
Risk of lung ca in exposed = 45/300 = 15%
Risk of lung ca in unexposed = 5/700 = 0.7%
Attributable risk = (15/100)- (0.7/100) = 14.3
Attributable risk is the number of cases that are due to smoking so you take away the naturally occurring cases (“that would happen anyway”)
In Crookes (a population of 1000 people), 300 of them smoke. Of those who do smoke, 45 of them developed lung cancer. 5 of the non-smokers developed lung cancer. How many people would have to give up smoking to prevent one death from lung cancer?
Attributable risk = (15/100)-(0.7/100) = 0.143
NNT = 1/AR
= 1/0.143 = 6.99
So if 7 people stopped smoking you would prevent 1 death due to lung cancer in this population
Define sensitivity? Specificity ? PPV? NPV? And how to work out?
Sens - % correctly identified with disease (associated with increased false positives) a/(a+c)
Spec - %correctly excluded as not having the disease (low causes unnecessary follow ups) d/(b+d)
Positive predictive value= % of those with a positive test that actually have the disease a/(a+b)
Negative predictive value= % of those with a negative test who are actually disease free d/(c+d)
What is the Wilson screening criteria
INASEP
Important disease
Natural history of the disease must be understood e.g. detectable risk factors, disease marker
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
Disadvantages of screening
Over detection of sub clinical disease
Needless worry if the screening result comes back positive and/or exposure to harmful diagnostic tests e.g. colonoscopy after faecal occult blood.
Is this higher in low sensitivity of low specificity? Answer= low specificity!
Over-identification and treatment of sub-clinical and harmless disease.
Harm from the screening test or subsequent treatment e.g. antibiotic resistance in GBS pregnant women
lead time vs length time bias ?
Lead time bias= Early identification doesn’t alter outcome but appears to increase survival
e.g. patient knows they have the disease for longer
Length time bias= Disease that progress more slowly is more likely to be picked up by screening (i.e. symptom free and around for longer), which makes it appear that screening prolongs life.
Mnemonic for health inequality ?
PROGRESS Place of Residence (rural, urban, etc.) Race or ethnicity Occupation Gender Religion Education Socioeconomic status Social capital or resources
Definition of health
Key articles of human rights act of 1998
Definition of health: a state of complete physical, mental and social wellbeing. No merely the absence of disease or infirmity
Article 2 – right to life
Article 3- right to freedom from inhuman and degrading treatment
Article 8- right to respect for privacy and family life
Article 12- right to marry and found a family
Article 14- right to freedom from discrimination
Causes of errors
Sloth error – being lazy, not bothering to check results/ information for accuracy. There is incomplete evaluation.- improved by paying attention to detail, and checking information
Lack of skill – lack of appropirate skills teaching or practice- improved by being properly trained in your role and PPD!
Communication breakdown – unclear instructions or plans and not listening to others- improved by being approachable and listening. System failure Human factors Judgement failure Neglect Poor performance Misconduct
4 parts of negligence ? What is bolam ? Bolitho?
Was there a duty of care?
Was there a breach in that duty?
Was the patient harmed?
Was the harm due to the breach in care?
Bolam - Would a group of reasonable doctors do the same?
Bolitho - Would that be reasonable?
What are the 3 domains of public health?
Health improvement
Social interventions and preventing disease, promoting health and reducing inequalities
Health protection
Measures to control infectious disease risk and environmental hazards
Improving services
Organization and delivery of safe high quality services
What is the health needs assessment?
Is a way of systematically reviewing health issues to find a list of agreed priorities and resource allocations that will improve health and reduce inequalities
Needs assessment -> planning -> implementation -> evaluation -> repeat
What is the Bradshaw taxonomy of need? (4 types of need)
Felt need- individual perceptions
Feeling back pain
Expressed need- individual seeks help (demand)
Going to the Dr with back pain
Normative need- professional defines intervention
GP decides you need a physio
Comparative need- comparison
Compare all the referrals from GP X to physio to GP Y
What are the 3 approaches to HNA?
Epidemiological
Defines the problem and looks at the size of it using routine and primary data
Comparative
Looks at services received and compares with a similar area – may compare health outcomes
Corporate
Asks the local population and health profs what the needs are using focus groups etc
Pros / cons of epidemiological approach to HNA
pros
Uses existing data
Provides incidence mortality and morbidity data
Can evaluate services by trends over time
Cons
Quality of data is vsriable
Data collected might not be the data required
Doesn’t consider the felt needs or opinions of those its looking at
Pros / cons of comparative approach to HNA
Comparative
Pros
Quick and cheap if data available
Indicates whether services are better or worse in comparable areas
Cons
Difficult to find a comparable
Pros / cons of corporate approach to HNA
Corporate
Pros
Based on felt and expressed needs
Recognises the knowledge and experiances of those working in the population
Takes into account a wide range of views
Cons
Difficult to establish need from demand
Groups may have vested interests
May be influences by political agendas
3 types of health behaviour
Health behaviour
Prevent disease
E.g go for a run, wear sun screen etc
Illness behaviour
Going to the DR
Sick role behaviour
Taking medications
3 types of behaviour change
Transtheorectical model- Pre contemplation- not ready yet Contemplation Preparation Action Maintenance / relapse
Nudge – nudge the environment for positive change – fruit near the checkouts
Theory of planned behaviours – best predictor of change is intention
Persons attitude to the behaviour (smoking is bad)
Subjective norms- percieved social pressures/norms (GP wants me to give up)
Perceived behaviours – how well the person thinks they can do it (I can do it!!)
What 3 principles is resource allocation based on?
Egalitarian
Based on the idea that the NHS was founded on the requirement to provide all care that is necessary and required to everyone
Equal for everyone
Maximising
Maximise public utlity/ profits? – an act is evaluated soley in terms of its consequences – will it be beneficial?
Give to those who it is most likely to benefit the most
Libertarian
Each is responsible for their own health
The german health incentive scheme – change health behaviours and get bonuses for partipating
What are never events? What do they lead to? Egs?
Serious, largely preventable patient safety incidents that should not occur if the available preventative measures have been implemented
Financial penalties, affect trust reputation, CQC visits
Surgical - wrong site / retained foreign object
Psych - escape of a transfer pt
Medical - wrong route of chemo administration / opioid overdose
A group of patients with lung cancer and a group of age matched controls are compared by looking at pack life history to assess the impact of smoking on lung cancer.
What type of study is this?
Give an example of a covariate?
What type of bias may interfere with results?
Retrospective case-control
E.g. work exposure, gender, type of tobacco, level of passive smoking
Selection bias e.g allocation bias (inappropriately matched controls) and information bias e.g. recall and reporting bias
3 benefits of cohort studies
Identify causation
Ethical assessment of RF (if exposure was thought to be dangerous would not be fair to do a RCT )
Allows assessment of multiple risk factors
A new diagnostic test is being developed: 100 people known to have the disease are tested as are 200 disease-free controls. Ninety of the cases yield positive tests, as do 30 of the controls.
What is the specificity of the test?
What is the positive predictive value?
What do these mean?
85%
75%
85% specific means 85% of people without the disease were correctly excluded. 75% PPV means of those who had a positive result, 75% actually had the disease.
Why do you notify public health
So HPA can take control measures
You may be the only one to tell them
Duty of registered medical practitioners
Role of the consultant in communicable disease control
Surveillance - Notification / lab data to monitor diseases
Prevention - Eg vaccination
Control
Basics of outbreak management
Clarify problem - make a diagnosis
Decide if its an outbreak - 2 or more related cases
Gain help - microbiologist, consultant in infectious disease, health visitors
Call an outbreak meeting
Identify cause
Control measures
4 causes of homelessness
Relationship breakdown
Domestic abuse
Dispute with parents
Bereavement
Health problems faced by homeless
Infectious disease Foot and teeth health Resp problems Violence / rape Sexual health Mental illness Nutrition Addiction
Barriers to healthcare for travellers
Reluctance of GPs to register them Illiteracy Communication difficulties Lack of permanent site Mistrust of professionals
Barriers to healthcare with homeless
Access
-Location / discrimination
Lack of integration between primary care and other agencies
-housing, social services, criminal justice
Other things on mind
-don’t prioritise health
May not know where to find help
What is an asylum seeker, refugee, humanitarian protection?
AS- someone who has made application for refugee status
R- granted asylum - usually lasts 5 years
HP - failed to get asylum but serious threat if returned - usually lasts 3 years
Asylum seekers get?
Vouchers to live off NASS support package Access to NHS Not allowed to work No choice where they go
Physical / mental health with asylum seekers ?
Common illnesses / those specific to country
Injuries from war / travelling
Lack of health screening / immunisations
Malnutrition
Abuse
Untreated chronic disease
Communicable disease
Mental -PTSD Depression Psychosis Self harm
Why is safety compromised in healthcare?
Complexity
Resource intense
Shared responsibility
Error classification based on Intention?
Action?
Outcome?
Context?
I - failure of planned action to achieve desired outcome
- skill based
- rule based - didn’t follow rules
- knowledge based
Action
- task specific - eg wrong vessel
- Generic factors - Eg wrong order / omission
Outcome
-Near miss / death
Context
-Interuptions, team factors
2 perspectives of error? And cons
Person approach
- error due to individual, focuses on the unsafe act
- Anticipation of blame -> cover up
System
-Errors are due to many factors
Strategies to reduce errors
Simplification and standardisation of clinical practice
Checklists
IT
Team training
Risk management programs
Tools of risk identification
Incident reporting Complaints and claims Audits External accreditation Active measurement
What is a never event
Preventable patient safety incident which should not occur
4 parts of negligence
Is there a duty of car?
Is there a breech of this duty
Did the patient come to harm
Did the breach cause the harm
Negligence, why do things go wrong?
System failure
Human factors
-Personal
Teamwork
Environment
Judgement failure
- Analytical / intuitive
- defective decision making
Neglect
Poor performance
Repeated small mistake
Misconduct
Benefits of teaching diversity
Better outcomes for patients
- doctors identify their problems more accurately
- better patient adherence
More satisfying patient encounters
- more Effcient time spending
- patients more satisfied
Benefits and risks of social media
Benefits
- Esablish good networks
- enagange in debates
- improve patient access to services
Risks
- Loss of personal privacy
- potential breaches of confidentiality
- risk of posts being reported
GMC duties of a doctor
Make the care f your patient your first concern
protect and promote the health of the public
Provide a good standard of practice and care
Treat patients as individuals and respect their dignity
Work in partnership with patients
Be honest and open and act with integrity
Relative risk reduction?
Risk unexposed - risk exposed
All over unexposed
Name 3 things you can offer a newly presenting drug user
Health check Screening for BBVs Contraception Smear Immunisation Information on drug services Eg needle exchange status
Principles of addiction treatment
Harm reduction -Advice on risky behaviour -BBV advice -Testing 0contraception
Brief intervention
- Explain risks / effects
- advice on controlled use
- setting limits
- cognitive based approaches
Team working
- referral to sexual health
- referral for specialist advice
Aims of treatment for drug use
Reduce harm to user, family and society
Improve health
Stablise lifestyle
Reduce crime
What is domestic abuse
Any pattern of controlling, threatening, or violence / abuse between those aged 16 and over who may have been family members or intimate partners
Domestic abuse impact on health
Trauma
Somatic problems - Headche, GI, chronic launch , LBW / premature
Psychological / psychosexual
- PTSD, suicide,
- depression, anxiety, eating disorder
- Substance misuse
Role of doctor in Domestic abuse
Healthcare records important in court
Display helpline and give contact cards
Focus on patients safety
Ask direct questions
Be non judgemental
Risk levels and what should you do for DA ?
Standard - evidence does not suggest likelihood of causing serious harm
Medium - Identifiable indicators of risk of serious harm
- Unlikely to happen without change in circumstance
- > Give DA abuse contact details
High - Risk of imminent harm
- > Refer to
- MARAC (multi-agency risk assessment conference) - Identifies risk and provides appropriate services
- IDVAS - supports women (a voice for MARAC)
- DHR - Domestic homicide review - if death of a persons aged over 16 and related to violence
What tool can be used to assess risk in DA
DASH
Domestic, abuse, stalking, harassment
How do you assess health equity ?
Inequality is assessed and must be explained to decide if its inequitable
Equality may not always be equitable
Need, demand and supply in terms of HNA
Need - Ability to benefit from an intervention
Demand - What people ask for
Supply - What is provided
What is positive and negative conditioning in relation to addiction
Positive - increased intensity of desire to use
Negative - do not quit as poor experiences Eg nausea
What are the comps of drug use
Physical Injection complications Overdose BBV Side effects Eg constipation
Social
Criminal acts
Social exclusion
Poverty
Psychological
Guit
Cravings
Legal level of alcohol to work in NHS / drive
80mg%
3 features of Alcohol dependent syndrome
Need 3 features
Tolerance Withdrawal Neglect of other activities Spending more time Continued use despite negative effects Failure to control use
CANT STOP
Triad of wernickes
Ataxia
Opthamoplegia
Acute mental confusion
Drugs for alcohol stopping abuse
Disurfiram
Acamprosate - GABA Blocker
Naltrexone
What 3 parts of evaluations of health servicws
Structure
Process
Outcome
Issues with health outcomes
Time lag
Large sample sizes needed
Data quality issues
Quality of care - maxwell’s dimensions
Effectiveness Efficiency Equity Accessibility Appropriateness Acceptability
General framework of evaluation of heath services
Define the service What are the AIMS of the service Framework - structure, process outcome Methodology - Qual / quantitative Results - recommendations
Emotional needs in elderly
[PISAA]
Security Attention Autonomy Intimacy Part of wider community
Theory of planned behaviour factors?
intention - best predictor of change
Persons attitude to the behaviour (smoking is bad)
Subjective norms- perceived social pressures/norms (GP wants me to give up)
Perceived behaviours – how well the person thinks they can do it (I can do it!!)
[perceived behaviours are Subjective to Attitudes and Intention]
Define Epigenetics – Allostasis – Allostatic load – Salutogenesis – Emotional intelligence
Epigenetics – expression of genome depends on he environment
Allostasis – stability through change, our physiological systems have adapted to react rapidly to environmental stressors.
Allostatic load – long term overtaxation of our physiological systems leads to impaired health (stress)
Salutogenesis – favourable physiological changes secondary to experiences which promote healing and health.
Emotional intelligence – the ability to identify and manage one’s own emotions, as well as those of others
Name 3 things primary care is for
Preventing illness
promoting health
working in a primary health team
Shared decision making with pts
Managing illness over time
Name 3 parts of health improvement
o Inequalities o Education o Housing o Employment o Lifestyles o Family/community o Surveillance and monitoring of specific diseases and risk factors
Name 2 parts of health protection
o Infectious diseases o Chemicals and poisons o Radiation o Emergency response o Environmental health hazards
Name 3 parts of improving services
o Clinical effectiveness o Efficiency o Service planning o Audit and evaluation o Clinical governance Equity
Name 3 types of screening
- Population-based screening programmes
- Opportunistic screening
- Screening for communicable diseases
- Pre-employment and occupational medicals
- Commercially provided screening
Define screening
A process which sorts out apparently well people who probably have a disease (or precursors or susceptibility to a disease) from those who probably do not.
What is the prevention paradox
A preventive measure which brings much benefit to the population often offers little to each participating individual
2 approaches to prevention
- Population approach – preventative measure eg. dietary salt reduction through legislation to reduce bp
- High risk approach – identify individuals above a chosen cut off and treat – eg. screening for high bp
Name 4 criteria for screening
• The condition
o Important health problem
o Latent / preclinical phase
o Natural history known
• The screening test
o Suitable (sensitive, specific, inexpensive)
o Acceptable
• The treatment
o Effective
o Agreed policy on whom to treat
• The organisation and costs
o Facilities
o Costs of screening should be economically balanced in relation to healthcare spending as a whole
o Should be an ongoing process
Name 2 bias in screening
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.
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 do you use to describe epidemiology of a disease
- Time
- Place
- Person [Age Gender Class Ethnicity]
Calc for incidence rate
(No.of persons who have become cases in a given time period)
/
(Total person-time at risk during that period)
What is attributable risk
The rate of disease in the exposed that may be attributed to the exposure
Incidence in exposed - Unexposed
What is relative risk
Ratio of risk of disease in the exposed to the risk in the unexposed
Risk in exposed / unexposed
[Shows strength of association]
what is Relative risk reducion
reduction in rate of the outcome in the intervention group relative to the control group
1-Relative risk
What is absolute risk reduction
Risk in unexposed – Risk in exposed
What is number needed to treat
number of pts need to treat to prevent 1 outcome
1/ARR
Name 2 criticisms of theory of planned behaviour
no temporal element
lack of direction / causality
What is opportunity cost
to spend resources on ONE activity – means a sacrifice in terms of lost opportunity cost elsewhere
What is economic efficiency
achieved when resources are allocated between activities in such a way as to maximize benefit (may not be equal/fair distribution)
- May save more lives by trading efficiency with equity (i.e. save more lives, but may not be fair)
What is an economic evaluation
comparative study of the costs and benefits of health care interventions.
2 ways to measure benefit of interventions
QALY
Monetary value – how much someone is going to pay in tax/earn
natural units” (BP/pain scoref/number of cases detected)
Cost benefit vs cost utility analysis
- Cost-utility analysis: outcomes measured in QALYs
* Cost-benefit analysis: outcomes measured in monetary units
What do we look at with QALYs
Cost of new treatment
Effectiveness of new treatment
Dominated = cost is positive, but incremental QALYs negative,
Dominant = cost negative but incremental QALY positive
