Intro, health needs assessment, screening: Flashcards
What is epigenetics?
Expression of genome depends on the environment
What is allostasis?
Stability through change. Out physiological systems have adapted to react rapidly to environmental stressors.
What is allostatic load?
Long term overtaxation of our physiological systems leads to impaired health (stress)
What is Salutogenesis?
Favourable physiological changes secondary to experiences which promote healthing and health (e.g. exercise)
What is emotional intelligence?
The ability to identify and manage ones own emotions, as well as those of others.
What Abx should be given in those with one of: otitis media, sinusitis, LRTI?
Amoxicillin
What Abx should be given in a UTI?
Trimethoprim or nitrofurantoin
What Abx should be given in tonsillitis?
Penicillin
Outline 5 things primary care is useful for:
- Managing illness and clinical relations over time
- Preventing illness
- Promoting health
- Working in a primary health care team
- Managing clinical uncertainty
What is public health?
The science and art of preventing disease, prolonging life and promoting health through organised efforts of society
What are the 3 domains of public health?
- Health improvement (societal interventions)
- Health protection (measures to control infectious disease risks and environmental hazards)
- Improving services (organisation and delivery of safe, high quality service)
Give 3 examples of health improvements:
- Reducing inequalities
- Education
- Housing
Give 3 examples of health protection:
- Infectious diseases
- Chemicals and poisons
- Radiation
Give 3 examples of improving services:
- Clinical effectiveness
- Efficiency
- Audit and evaluation
What needs to be done before performing public health intervention?
Health needs assessment
What is a health needs assessment?
‘A systematic method for reviewing the health issue facing a population’, leading to agreed priorities and resource allocation that will improve health and reduce inequalities.
What is a health need?
Need for health e.g. measured using mortality, morbidity and socio-demographic measures
What is a health care need?
Need for health care, ability to benefit from health care. Depends on the potential of prevention, treatment and care services to remedy health problems.
What is a need, demand and supply?
Need - ability to benefit from an intervention
Demand - what people ask for
Supply - what is provided
What is felt, expressed, normative and comparative need?
Felt need - individual perceptions of variation from normal health
Expressed need - individual seeks help to overcome variation in normal health (demand)
Normative need - Professional defines intervention appropriate fro the expressed need
Comparative need - comparison between severity, range of interventions and cost
What are the 3 methods/approaches to health need assessment?
1) Epidemiological
2) Comparative - compares the services received by a population with others
3) Corporate - asks populations what their health needs are
Give 2 advantages and 2 disadvantage for each health needs assessment approach:
1) Epidemiological:
(+ves):
- Uses existing data
- Can evaluate services by trends over time
(-ves):
- Quality of data variable
- Does not consider felt need/peoples opinions
2) Comparative: (+ves): - Quick and cheap if data available - Gives relative performance (-ves): - May be hard to find comparative population - Data may not be high quality
3) Corporate:
(+ves):
- Based on felt or expressed needs of the population
- Takes into account experience of those working in the population
(-ves):
- Difficult to distinguish ‘need’ from ‘demand’
- Groups may have vested interests
What is primary prevention? give an examples
Preventing the disease before it has happened (eating healthily)
What is secondary prevention?
Catching disease in the pre-clinical or early phase (mammograms)
What is tertiary prevention?
Preventing complications of disease (cardiac rehab programmes after MI)
List 2 approaches to prevention:
- Population approach - preventative measure e.g. dietary salt reduction
- High risk approach - identify individuals above a chosen cut off and treat e.g. screening high bp
What is the prevention paradox?
A preventative measure which brings much benefit to the population but often offers little to each participating individual
What is screening?
A process which sorts out apparently well people who probably have a disease (or precursors or susceptibility to a disease) from those who do not. (NOT DIAGNOSTIC)
What type of screening programmes exist?
- Population based
- Opportunistic screening
- Screening for communicable diseases
List 2 disadvantages of screening:
- Exposure of well individuals to distressing or harmful diagnostic test
- Preventative interventions that cause harm to the individual
What criteria is used to assess whether screening is appropriate?
Wilson and Junger criteria
What are the 4 factors in the Wilson and Junger criteria?
1) The condition:
- Important health problem
- Latent/preclinical phase
- Natural history known
2) Screening test:
- Suitable (sensitive, specific, inexpensive)
3) Treatment:
- Effective
- Agreed policy on what to treat
4) Organisation and cost:
- Facilities
- Cost of screening should be economically balanced in relation to healthcare spending as a whole
In relation to screening, what is sensitivity?
The proportion of people with the disease who are correctly identified by the screening test (a/a+c)
In relation to screening, what is specificity
The proportion of people without the disease who are correctly excluded by the screening test (d/b+d)
What is positive predictive value?
The proportion of people with a positive test result who actually have the disease (a/a+b). This is higher if the prevalence is higher.
What is negative predictive value?
The proportion of people with a negative test result who do not have the disease (d/ c+d)
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. e.g. someone with a slowly progressing disease is more likely to be pick up on screening than someone with severe disease due to the severe form being diagnosed through other means.
What are the types of observational studies?
- Case reports
- Ecological studies - routinely collected data to show trends
- Cross sectional study/survey - divides population into those without disease and those with the disease and collect data on them once at a defined time to find associations at that point in time.
- Case-control study - retrospective studies that take people with a disease and match them to people without the disease and study previous exposure to the agent in question.
- Cohort study - These studies start with a population without the disease and study them over time.
Give 2 advantage and 2 disadvantages of Cross sectional studies:
(+ves): - Relatively quick and cheap - Provide data on prevalence at a single point in time (-ves): - Risk of reverse causality - Risk recall bias and non-response
Give 2 advantage and 2 disadvantages of case-control studies:
(+ves):
- Good for rare outcomes
- Quick
(-ves):
- Difficulties finding controls to match with cases
- Prone to selection and information bias
Give 2 advantage and 2 disadvantages of cohort studies:
(+ves): - Less risk of bias - Risks can be determined (-ves): - Takes long time - Loss to follow up
What are the types of experimental/interventional studies?
- Randomised control trial
- Non-randomised control trial
List 2 advantages and 2 disadvantages in RCT:
(+ves): - Low risk of bias and confounding - Can infer causality (gold standard) (-ves): - Expensive - Time consuming - Ethical considerations
(disadvantage to NRCT is that it is very subjected to bias)
What is an independent variable?
A variable that can be altered in a study
What is a dependant variable?
A variable that is dependent on the independent variables or one that cannot be altered.
What is the odds of an event?
The ratio of of the probability of an occurrence compared to the probability of a non-occurence.
Odds= probability/ (1-probability)
What is odds ratio?
It is the ratio of odds fro exposed group to the odds for the not exposed group.
OR= (Pexposed/(1-Pexposed))/(Punexposed/(1-Punexposed))
When is odds ratio used?
It can be interpreted as relative risk when the event is rare. Used in case controlled studies.
What is epidemiology?
The study of the frequency, distribution and determinants of diseases and health related states in populations in order to prevent and control disease.
What is incidence, prevalence and person time?
Incidence = new cases/time
Prevalence = existing cases/ point in time
Person time = Measure of time at risk i.e. time from entry into a study to 1) disease onset 2) loss to follow-up 3) end of study. Used to calculate incidence rate which uses person time as denominator.
What is incidence rate?
= Number of persons who have become cases in a given time period/ total person-time risk during that period
What is attributable risk?
= Incidence in exposed - incidence in unexposed
What is relative risk?
= (Incidence in exposed)/(incidence in unexposed)
how many times more likely it is that an event will occur in the intervention group relevant to the control group
What is relative risk reduction?
Reduction in the rate of the outcome in the intervention group relative to the contol group
Absolute risk reduction?
Absolute difference in the rates of events between the two groups and gives an indication of the baseline risk and intervention effects
What is number needed to treat?
Number need to to treat is the number of patient you need to treat to prevent one bad outcome.
= 1/Absolute relative risk (ARR) [expressed as a decimal]
What are the 3 types of bias?
- Selection bias - systematic error in selecting participants, allocation of participants
- Information (measurement) bias - a systematic error in the measurement of classification of exposure or outcome (sources: observer, participant, instrument)
- Publication bias
What does confounding mean?
A situation in which the estimate between an exposure and an outcome is distorted because of the association of the exposure with another factor (confounder) that is also independently associated with the outcome.
What is reverse causality?
When the outcome causes the exposure.
Outline the criteria used for causality:
Bradford-Hill criteria:
- Strength of association
- Dose-response
- Consistency
- Temporality
- Reversibility
- Biological plausibility
- Coherence
- Analogy
- Specificity
Or simplified: (The Bad Dog Ate the Cat) T - temporality B - Biological Plausibility D - Dose-Response Relationship A - Association (strength of) C - Consistency
What is chance?
Random error for repeated samples/replicates/ Prevented by ensuring sufficient sample size.
How is chance detected?
Using CI and P-values
