Public Health + PPS Flashcards
differentiate between a suspected, probable and confirmed case of an infectious disease (e.g. a measles outbreak)
this will be defined by the case definition.
suspected - clinical features (e.g. fever and rash)
probable - clinical features + contact with confirmed case
confirmed case - clinical features and positive microbiology, serology etc.
what is a case definition?
set of standard criteria for deciding whether or not a person has a particular disease or health related event
define prevalence
a measure of the proportion of the population that has a given disease, condition or characteristic at a given time (or time period)
define point prevalence
no. cases at a point in time, compared with the total population
define period prevalence
no. cases identified over a period of time, compared with no. people in the population over this time period.
NB - not NEW cases (that’s incidence!), just existing cases
define incidence
frequency of NEW cases in a defined population in a specified time period
define cumulative incidence (risk)
no. NEW cases occurring over a given period of time in the population at risk at the BEGINNING of the time period
what 4 different relative measures come under the term “relative risk”?
prevalence ratio
risk ratio
rate ratio
odds ratio
what does relative risk measure?
measures the strength of association between exposure and disease
what are the 4 different measures of impact of a risk factor?
- attributable risk (aka excess risk)
- attributable risk fraction (or %)
- population attributable risk
- population attributable risk fraction (or %)
what is attributable risk?
the excess incidence of our outcome that can be attributed to the exposure
what does using an attributable risk fraction adjust for?
the fact that the exposed group would have had some disease anyway - AR fails to take into account the underlying, background rate.
i.e. - not all illness, even in the exposed group, will be due to the exposure
what does the attributable risk fraction tell us?
what proportion of disease IN THE EXPOSED GROUP is attributable to the exposure
what does population attributable fraction tell us?
what proportion of disease in the POPULATION that is attributable to the exposure
e.g. interpret PAF of 0.96 as “96% of (outcome) in the population are attributable to (exposure)
what is a cross-sectional study?
a study in which data are collected on each study participant at a single point in time
a SNAPSHOT
aka prevalence study
what are the two types of cross-sectional study?
descriptive and analytical
what do descriptive cross-sectional studies do?
what do they measure?
collect info on frequency and distribution of health-related exposures or outcomes, in a defined population.
measure point or period prevalence of the outcome OR exposure
how are data typically collected for a cross-sectional study?
surveys
what do analytical cross sectional studies do?
investigate the association between exposure to risk factors and the outcome of interest
(NB - the info is collected simultaneously on each individual - no temporality)
what are the differences between an analytical and a descriptive cross-sectional study?
descriptive cross-sectional studies basically just find the prevalence of an exposure or outcome, whereas analytical cross-sectional studies look at both exposures and outcomes to investigate the association between the two
what types of bias are cross-sectional studies particularly susceptible to?
recall bias - if asked about exposures that occurred a long time ago
non-response bias - always an issue with surveys - look at what the response rate is in the study
what measures are used in analysis of a cross-sectional study?
prevalence (of disease OR exposure)
prevalence ratio and prevalence odds ratios - for outcomes or exposures
list some advantages of a cross-sectional study
- quick, cheap and easy (ish!)
- provides prevalence of risk factors and disease in a defined population
- useful for health service planning
- repeated studies can monitor changes over time
list some disadvantages of a cross-sectional study
- exposure and disease info collected simultaneously = problems with temporal sequence - disease may modify exposure etc
- studying prevalent cases = can miss out cases with quick recovery, or short survival
- bias - recall, non-response
- not useful for rare conditions
what is an ecological study?
a study carried out at the population (or group) level rather than at the individual level
what is a multi-group ecological study?
aka ecological correlation study.
compares different groups (or areas) at a point in time
what is a time-trend study?
a type of ecological study, aka a time series study.
examines data in a population over time.
investigates if changes in incidence correlate with changes in exposures over time.
can be long (e.g. seasonal variation) or short (e.g. daily variation)
give examples of information that might be available at a population level, but not an individual level?
to study these, we do an ecological study
pollution income GDP and other national statistics per-capita consumption climate diet etc. etc.
give some reasons to study groups/populations
ecological studies
- to investigate differences between populations
- to study group-level effects (e.g. seat belt law only works at a group level!)
- convenience and availability of group level data (e.g. air pollution data is only available at a group level)
- quick and cheap study design!
give 4 reasons why ecological studies must be interpreted with caution
- confounders - often, you can’t adjust for these due to lack of data
- bias - data may be collected using different methods or definitions over time or in different places
- ecological fallacy
- migration of populations between groups can dilute differences
what is the “ecological fallacy”?
cannot assume that group level associations between exposure and outcome will also apply at the individual level
e.g. increased meat consumption and breast cancer rates - is it the meat-eaters who get the cancer?
what is a cohort study?
a “follow up” or “observational” study.
a cohort = a group of individuals sharing a common characteristic.
cohort studies take exposed and unexposed cohorts and follow them up over time, measuring incidence.
may be prospective or retrospective.
exposure is decided before outcome is observed.
what does a cohort study do?
compares INCIDENCE of an outcome in individuals with different exposure to a risk.
useful for investigating rare exposures, and/or several outcomes.
what measures does a cohort study provide?
risk ratio, odds ratio or rate ratio.
derived from incidence that is measured over the course of the study.
can use these to calculate AR and PAR
what are the two main types of cohort study?
prospective and retrospective.
prospectives start now and follow-up into future.
retrospective use existing data on exposures and outcomes.
how do retrospective cohort studies work?
all the events have already taken place, and records of them must exist.
a ‘start date’ for the study is in the past, and then records are checked to see what outcome(s) developed after the start date.
does NOT look back from an outcome to find the exposures!!
explain some factors that must be considered in selecting a study population for a cohort study
if it’s a common exposure, select your population before classifying by exposure - if it’s a rare outcome, you may need to recruit on the basis of exposure.
in selecting an unexposed group, you may choose either an internal or external comparison group, or compare with general population - but beware healthy worker effect
what are some important considerations to do with collection of outcome data in cohort studies?
might need a long follow-up period - loss to follow up (aka attrition) may be a serious problem!
data should be collected without knowledge of exposure status
how do you decide whether a risk or rate (ratio) is most appropriate for a cohort study?
if follow up times for all participants are similar, use risk.
if they vary, use rate so that person-time at risk is taken into account.
list 5 things that could explain an observed association between exposure and outcome in a cohort study
- true association
- bias
- confounding
- chance
- reverse causality
list the 9 Bradford Hill criteria for causality
- strength
- consistency
- dose-response
- temporality
- plausibility
- reversibility
- coherence
- analogy
- specificity
which of the 9 Bradford Hill criteria for causality do cohort studies do a good job of meeting?
temporality!
one of the few study designs that definitely meet this criteria
define bias
any error that results in a systematic deviation from the true estimation of the association between exposure and outcome
(a systematic error which leads to a distortion of the truth)
list some of the important biases affecting cohort studies
loss to follow up (selection bias)
non-participation (selection bias)
classification of outcome and exposure (observer bias)
define confounding
situation where a factor is associated with the exposure of interest, and independetly influences the outcome, but does NOT lie on the causal pathway
e.g. grey hair and back pain are associated - is this a causal relationship?
no! age is a CONFOUNDER here.
list some strengths of cohort studies
- useful for rare exposures
- can study effect of exposure on a range of outcomes
- if accurate and detailed exposure assessment is carried out, can assess for a dose-response relationship
- data on potential confounders can also be collected (if prospective)
- meets temporality!!
list some limitations of cohort studies
- large sample size may be required
- can’t use for rare outcomes
- costs (with propsective)
- time required for follow-up (with prospetive)
- retrospectives don’t usually have as accurate and consistent exposure assessment, or data on confounders
what study design is useful for rare exposures?
cohort study
what study designs should be avoided for studying a rare outcome?
cross-sectional
cohort
describe the study design of a case-control study
individuals with the outcome of interest (cases), and individuals without the outcome (controls) that match the cases on some demographic factors, are identified from a population.
then look back to identify how many individuals in each group were exposed/unexposed.
what things must be considered when deciding how to carry out case selection for a case-control study?
need a precise case definition, with clear inclusion and exclusion criteria set BEFORE selection begins.
will you be using prevalent or incident cases?
should you use incident or prevalent cases for a case-control study?
generally, incident cases preferred.
prevalent cases may be abnormally more or less severe (e.g. if less severe ones have recovered, or if more severe ones have died)
the disease influences how many cases picked up by prevalent or incident cases.
if you use prevalent cases, you can’t distinguish between factors associated with the rates of the disease, and factors associated with the disease PERSISTING
what considerations must be made when selecting controls for a case-control study?
controls should represent exposure distribution of the population from which the cases were drawn.
need inclusion and exclusion criteria that are similar to that for cases (but obvs no disease!).
need to be careful where you source controls from e.g. if cases are hospital based, should controls also be hospital based? won’t represent general population but would be more similar to cases…
Matching can be done at individual or group level (e.g. match individual controls to a case, or e.g. if case group is 70% male, ensure control group is also 70% male)
Beware overmatching - when matching variable is closely related to exposure variable
what is a nested case-control study and why do one?
a case-control study carried out within a full cohort study.
e.g. cohort study of outcome A following exposure A, could also carry out a nested case-control looking at exposures B, C and D in relation to outcome A. (i think??)
avoids selection bias, as cases and controls arose from same population.
also avoid info bias as all the same data collection is carried out on all participants.
avoids reverse causality
what measure is used in analysis of a case-control study?
odds ratio of exposure
list some biases affecting case-control studies
observer bias - ideally, researcher collecting exposure should not know case-control status
reporting (response/recall) bias - cases may remember exposures better than controls e.g. cases of asbestosis more likely to remember that an old work place has asbestos than controls!
list some strengths of case-control studies
- relatively cheap and quick
- useful for rare outcomes
- can study effect of multiple exposures on disease risk for a single disease
list some limitations of case-control studies
- potential for selection/information bias
- problems with temporality - possible reverse causality
- no good for rare exposures
- no good for multiple outcomes for a single exposure
- can’t estimate incidence or prevalence of a population
what type of study design is useful for studying rare outcomes/diseases?
case-control
what is an intervention study?
a study in which participants are actively allocated an intervention by the investigators
i.e. an experiment
what is a randomised controlled trial?
Randomised allocaation to intervention or control.
Controlled - use of a contemporary comparison arm, with participants given nothing/placebo/usual treatment.
Trial - an experimental study
why do an intervention study?
observation studies are more subject to bias and confounding.
RCTs provide GOLD STANDARD for causality
give some different types of randomisation that might be used in an RCT
stratified randomisation
blocked randomisation
systematic randomisation
simple randomisation
what are the benefits of blinding in an RCT, and who should be “blind”?
avoids measurement/reporting/analytical bias.
investigator, participant and statistical analyst should all ideally be blind.
explain the difference between an efficacy and an effectiveness trial?
in an efficacy trial, you are testing the maximum effect of an intervention if used in a closely monitored setting (e.g. the effect of a drug when patients are supervised taking it each day, or given lots of reminders etc).
in an effectiveness trial, you are looking at what the effect of an intervention is in routine clinical practice - this is more generalisable.
i.e. in an efficacy trial a drug might have X effect, with patients receiving daily reminders to take the drug at correct dose, time etc.
but in an effectiveness trial, the drug will then have Y effect (lower than X), because some patients will take it at the wrong time of day, or miss doses etc
what is a cluster randomised trial and when might it be used?
allocation of groups rather than individuals e.g. entire schools, or GPs.
needed when the intervention is at group level e.g. free milk in schools.
also useful if contamination between intervention and control groups is likely.
BUT - need larger sample size
explain the difference between intention-to-treat analysis and per protocol analysis, as used in an RCT
ITT should always be the primary analysis of an RCT - outcome is compared between study groups according to their initial allocation, regardless of any loss to follow up, or switching between groups.
this ensures comparability and avoids potential selection biases that might arise.
a per-protocol analysis can tell you the true potential effect of an intervention, if e.g. compliance was improved.
only participants who received intervention according to protocol are included in analysis.
what measures might be used in analysis of an RCT?
risk ratio, rate ratio, relative risk reduction.
absolute risk reduction
numbers needed to treat (NNT)
briefly list some ethical issues associated with RCTs
control group actively denied the intervention
use of placebo - generally, give the current “usual” treatment, rather than replacing that with a placebo
informed consent
what are “stopping rules” in relation to RCTs?
to meet ethical requirements, RCTs will usually have predefined stopping rules to ensure that if a trial is showing clear harm or benefit early on, it is not continued.
This avoids undue risk to participants, depriving control group of an effective intervention, or continuing an ineffective intervention
give some strengths of RCTs
- minimise risk of bias and confounding (especially if properly randomised and blinded)
- can study multiple outcomes
- can measure “incidence” of outcome
- provides strong evidence of causal relationship
give some limitations of RCTs
- EXPENSIVE
- may need long follow up
- risk of high drop out rates
- ethical concerns
- RCTs may end up with conflicting results anyway
what is the aim of primary prevention?
to prevent a disease from occurring.
carried out when no disease is present, done by reducing exposure or risk factor levels.
give some examples of primary prevention
lifestyle changes to reduce CVD risk.
fluoridation of drinking water to prevent tooth decay.
childhood imms to prevent communicable diseases.
what is the aim of secondary prevention?
detect early disease in order to alter the course of the disease.
also, prevention aimed at preventing a disease from recurring.
give examples of secondary prevention
SCREENING!
e.g. screening for breast cancer allows earlier treatment, altering course of disease.
also, treatment with aspirin to prevent recurrence of a heart attack.
what is the aim of tertiary prevention?
to minimise disability and prevent complications
give some examples of tertiary prevention
rehabilitation after a stroke.
treatment to prevent death after a heart attack.
explain the prevention paradox
a preventative measure which brings a big benefit to the population, often offers little to each individual.
e.g. seat belt law - for every 1 life saved, 400 people have to wear their seatbelt everyday for 40 years.
so there’s 399 people who have received no benefit to their survival from wearing a seatbelt daily for 40 years!
healthcare e.g. is statins for CVD
explain the population vs high risk approaches to prevention?
population approach means targeting an entire population with a preventative measure, offering each individual little benefit in exchange for a reduction in overall population risk.
high risk approaches target only those at high risk of an outcome.
NB - pop. approach isn’t always EVERYONE, might be e.g. all infants
give some advantages of a population approach to prevention
- potential to benefit the whole population
- “behaviourally appropriate”
? not sure what this means - maybe that it’s seen as good to spend public money on strategies that can benefit everyone?
give some disadvantages of a population approach to prevention
- small benefit to individuals
- poor motivation of subjects
- poor motivation of physicians
- benefit-to-risk ratio may be low
give some advantages of a high-risk approach to prevention
- intervention is appropriate to the individuals targeted
- subjects and physicians are more motivated
- benefit-to-risk ratio is good
give some disadvantages to the high-risk approach to prevention
- screening costs (have to identify who is at high-risk, and this costs money/resources!)
- temporary effect
- limited effect
- “behaviourally inappropriate” ??
define screening
a process which sorts out apparently well people (i.e. those without symptoms) who PROBABLY have a disease (/precursors/susceptibility to a disease) from those who PROBABLY do not.
NB - not intended to be diagnostic
what are the main purposes of screening?
primary or secondary prevention.
secondary - e.g. screening by mammogram for breast Ca to treat it early
primary - screening to identify people with risk factors and reduce risk factor levels (e.g. NHS health checks, well man/woman checks)
give some aims of screening
- reduce risk of developing disease
- provide treatment
- provide information (e.g. pre-natal screening for genetic disorders)
define sensitivity
proportion of people with the disease who are correctly identified by the screening test
define specificity
the proportion of people without the disease who are correctly excluded by the screening test
define positive predictive value
the proportion of people with a positive test result who actually have the disease
define negative predictive value
the proportion of people with a negative test result who do not have the disease
which 2 of the 4 measures of effectiveness of screening are affected by underlying prevalence?
PPV and NPV.
sensitivity and specificity are specifically about the screening TEST - they will not change unless the test is altered.
if prevalence of a disease decreases, what happens to PPV and NPV?
PPV will decrease, NPV will increase
what three criteria for screening must the CONDITION meet?
- condition should be an important health problem
- natural history of the condition should be understood
- there should be a detectable early stage
what three criteria for screening must the TREATMENT meet?
- there should be an accepted treatment for the disease
- facilities for diagnosis and treatment must be available
- adequate health service provision should be made for extra clinical workload resulting from screening (e.g. need to be able to do the extra breast surgeries before you start screening people for breast Ca!)
what three criteria for screening must the TEST meet?
- a suitable test should be devised for the early stage of a condition
- the test should be acceptable
- intervals for repeating the test should be determined (e.g. cervical screening every 3-5 years)
what two criteria for screening must the RISKS AND BENEFITS meet?
- there should be an agreed policy on whom to treat
- costs must be balanced against benefits
also - risks (physical and psychological) should be less than benefits!
who came up with the 10 (ish) criteria for screening?
Wilson and Jungner
only important in case they say ‘list the Wilson screening criteria’
what are the main biases that can affect studies evaluating screening?
selection bias
lead-time bias
length-time bias
what is the best study design to use to evaluate a screening programme?
RCT - individual or cluster
how does selection bias affect evaluation of screening programmes?
people who choose to participate in screening programmes may be different from those that don’t bother
e. g. may be at higher risk - family hx of breast Ca = more likely to attend breast screening
e. g. may be at lower risk - women in higher SE groups are more likely to attend cervical screening, but are at lower risk
explain lead time bias
can occur when survival time is used as outcome to assess screening.
patients in screening group appear to have a longer survival time, as disease is being diagnosed earlier (at point of screening, rather than when symptoms develop) - however, survival time is actually the same.
explain length-time bias
a bias in which individuals with slower growing/progressing, less aggressive disease are more likely to be detected by screening, making screening appear to have better outcomes (as these individuals would have had a better outcome than those with a rapidly progressing, aggressive disease anyway)
give some examples of different types of screening
- population- based (“mass”) screening programmes
- opportunistic screening e.g. GPs doing BPs when patients come in for any health issue
- Screening for communicable diseases
- Pre-employment and occupational medicals e.g. vision tests for commercial drivers
define bias
systematic deviation from a true estimate of the association between exposure and outcome
what are the two main categories of bias?
selection bias
information (aka measurement) bias
define selection bias
a systematic error in selection of study participants, or in their allocation to different study groups
what type of selection bias affects cross-sectional studies?
non-response
what types of selection bias affects cohort studies?
healthy worker effect
loss to follow-up
how can selection bias affect case-control studies?
selection of cases
selection of controls
how can selection bias affect intervention studies?
systematic selection for intervention/control groups (rather than true randomisation)
define the validity of a measurement
the degree to which a measurement measures what it is meant to measure
define the reliability of a measure
the degree to which the results obtained by a measurement procedure can be replicated
give some examples of different types of information (measurement) bias
inaccurate measurement/classification of either exposure or outcome.
misclassification can be differential or non-differential
give some examples of sources of information bias
observer/researcher - observer bias
participant - recall bias
instrument - e.g. wrongly calibrated instrument
what does differential misclassification result in?
bias - in either direction.
e.g. measurement of BP in two samples by two nurses using two BPs
what does non-differential misclassification result in?
underestimation of any true association
(i.e. moves RR closer to 1)
this is a random misclassification, that’s completely independent of exposure/outcome status
what steps can be taken to avoid information biases?
- blinding
- use of objective measures
- use of records rather than recall
- use of automated instruments rather than observers
what is confounding?
the situation where a factor is associated with the exposure of interest, and independently influences the outcome, but does NOT lie on the causal pathway
how can confounding be controlled for at the study design stage?
- restriction
- randomisation
- matching
how can confounding be controlled for in the analysis of a study?
- stratification
- statistical modelling
equation for prevalence
no. cases of the disease at specific time point/period ////////////// total no. people in the population at same time point/period
equation for risk
all NEW cases of disease in population over specific time period ///////// total population at start of time period
equation to calculate odds of getting disease
no. new cases of disease //// no. people still disease free
(all in a specified time period)
equation for incidence rate
no. NEW cases of disease in a specified time period //// person-time at risk in that time period
equation for risk ratio
risk in the exposed group
//
risk in the unexposed group
equation for odds ratio of outcome
odds of outcome in exposed group
///
odds of outcome in unexposed group
equation for incidence rate ratio
incidence rate in the exposed group
///
incidence rate in unexposed group
equation for attributable risk (AR)
incidence (rate) in exposed - incidence (rate) in unexposed
equation for attributable risk fraction
AR
/////
incidence in exposed group
express as decimal or %
equation for population attributable risk (PAR)
incidence in whole population - incidence in unexposed group
equation for population attributable fraction (PAF)
PAR
///
incidence in whole population
equation for odds ratio of exposure
odds of exposure among cases // odds of exposure among controls
equation for absolute risk reduction/difference (ARR/ARD)
incidence in control group - incidence in treatment group
equation for number needed to treat
1 / ARR
equation for sensitivity
true positives / no. people with the disease
a / a+c
equation for specificity
true negatives / no. people with no disease
b / b+d
equation for PPV
true positives / no. positive results
TP / TP+FP
a / a+b
equation for NPV
true negatives / no. negative results
TN / TN+FN
d / c+d
give some examples of population approach prevention efforts
sugar tax
folic acid in flour
legislation for dietary salt reduction
give an example of a high-risk approach to prevention efforts
enhanced screening for other CVD risk factors for people with high blood pressure.
only giving BCG vaccine to babies with certain risk factors.
list some factors that contribute to promoting ‘excessive energy intake” i.e. overeating, consuming too many calories
genetics employment type (shift work) early developmental factors TV viewing/advertisements characteristics of food eaten (e.g. energy density, portion size might mean more calories consumed in one sitting) reduced physical activity (less energy needed) sleep environmental cues psychological factors
define malnutrition
deficiencies, excesses or imbalances in a person’s intake of energy and/or nutrients - includes undernutrition (stunting, wasting, underweight, micronutrient deficiencies) and overweight (obesity, diet-related NCDs)
list some chronic medical conditions requiring nutrition support
this is why Drs should have understanding of food behaviours!
cancer CF coeliac IBD/IBS T1DM T2DM failure to thrive EDs overweight/obesity
Drs should be able to understand and respond to/advise patients
list some early influences on feeding behaviour
- maternal diet and taste preference development
- breastfeeding - has role for taste preference and bodyweight regulation
- parenting practices/styles
- age of introduction of solid food
- types of food exposed to during weaning and beyond
what are some parent feeding practices that can influence infant/child feeding behaviours?
- modelling ‘healthful’ eating behaviours
- responsive feeding (recognising hunger and fullness cues)
- providing a variety of foods
- avoiding pressure to eat
- restriction
- authoritative parenting
- not using food as a reward
- indulgent/neglectful feeding practices
what are non-organic feeding disorders (NOFEDs)?
feeding aversion, food refusal, food selectivity, fussy eaters, failure to advance to age-appropriate foods, negative mealtime interactions.
high prevalence in <6 yo
parents with NOFEDs shown as often using maladaptive parental feeding practices.
what are the different eating disorders, as classified in the DSM?
anorexia nervosa
bulimia nervosa
binge eating disorder
OSFED - other specified feeding or eating disorder
what are the three basic forms of dieting associated with restriction of food intake?
- restricting total amount of food eaten
- not eating certain types of food
- avoid eating for long periods of time
list some problems with ‘dieting’
1) RF for developing eating disorders
2) often loss of lean body mass, not just fat
3) slows metabolic rate and energy expenditure
4) chronic dieting can disrupt ‘normal’ appetite responses and increase subjective sensations of hunger
5) weight cycling (repeated diet - relapse) often leads to ‘overshoot’ - accelerates overall weight gain
explain the externality theory of obesity
idea that normal weight people are responsive to internal homeostatic cues, while overweight people eat according to:
- external cues
- no compensation after preload
- time of day
- offer lurid descriptions of desserts
- sensory food cues
but this theory is a bit too broad/general
briefly explain the restraint/boundary model of dietary restraint and disinhibition
idea that ‘normal’ eaters have a min level of food intake (hunger boundary) and a max level (satiety) - eat intuitively within that.
restrained eaters have a ‘cognitive dietary boundary’ - how much they think they should eat, that’s lower than satiety.
if they break that boundary (as still hungry) - ‘what the hell’ effect, become disinhibited, and eat to satiety or beyond (often their satiety point is higher than normal as well).
leads to overall weight gain.
give some factors that might trigger disinhibition in restrained eaters
(restraint theory)
high energy preloads/belief of high energy preload (e.g. went on a run today therefore I can eat alllll the cake)
large portion size
alcohol
stress/cognitive load
strong emotion - positive or sad (celebratory vs comfort)
what are the stages in the healthcare services planning cycle?
needs assessment –> planning –> implementation –> evaluation –> needs assessment (repeat)
what three things do health needs assessments consider?
need - ability to benefit from an intervention
demand - what people ask for
supply - what is provided
what is NICE’s definition of “need” (for HNAs)?
ability to benefit from an intervention
what is a health needs assessment? NICE definition
a systematic method for reviewing the health issues facing a population, leading to agreed priorities and resource allocation that will improve health and reduce inequalities
explain the difference between health needs and health care needs
health need = need for health, concerning need in more general terms (e.g. measured through mortality, morbidity etc)
health care need = more specific, ability to benefit from health CARE - depends on potential of prevention/treatment/care services to remedy health problems.
HNAs usually cover both.
what are Bradshaw’s 4 different types of need?
felt need
expressed need
normative need
comparative need
what is ‘felt need’ as defined by Bradshaw?
individual perceptions of a variation from normal health
i.e. they feel they’re lacking in a certain aspect of health
limited by individual perceptions and knowledge of services.
what is ‘expressed need’ as defined by Bradshaw?
individual seeks help to overcome variation in normal health (demand)
i.e. they seek treatment/support to address an aspect of their health
what is ‘normative need’ as defined by Bradshaw?
where a professional defines an intervention appropriate for the expressed need
i.e. doctor says the patient needs to improve diet and exercise to reduce weight
what is ‘comparative need’ as defined by Bradshaw?
comparison between severity, range of interventions and cost - compare one group of people to another, what is the difference in what they have? does that mean one group needs something?
e.g. a rural village may identify a need for a well or a school if the neighbouring village has one
what are the 3 different approaches to HNA?
epidemiological
comparative
corporate
describe an epidemiological approach to HNA
very top-down approach,
basically uses surveys and secondary data sources (census, mortality and morbidity records, GP data etc) to evaluate burden of disease etc affecting a population
takes into account:
Person - who are the affected people - age, gender etc
Place - where and why, do prevalence and incidence vary geographically
Time - when do people get diseases? does it vary by season, cycles?
Statement of the problem - case definition
Prevalence and incidence
Services available and their costs
Effectiveness and cost-effectiveness of services
Quantified models of care and recommendations
Information and research requirements
what are some limitations/problems with the epidemiological approach to HNA?
very top down! required data may not be available variable data quality does not consider felt needs of people affected reinforces biomedical model of health
what types of measures for supply and demand might be used in an epidemiological HNA?
supply - staffing, budget, equipment, hospital beds, GP practices
demand - admissions, local population, waiting times
describe the comparative approach to HNAs?
compares services received by a population/subgroup with others e.g. geographically, by social class, by age etc.
looks at - health status, service provision, service utilisation, health outcomes.
measures variation in cost and service use.
fairly quick and inexpensive to achieve
what are some limitations/problems of a comparative approach to HNAs?
- may not identify the ideal/most appropriate level of provision/utilisation should be (you don’t know whether your point of reference is getting it right!)
- data might not be available/may be of variable quality
- hard to find appropriate comparative population
- links between usage rates and health outcomes can be hard to demonstrate
describe the corporate approach to HNA
structured collection of knowledge and views of stakeholders - focus group, interviews used
based on the demands, wishes and perspectives of interested parties - professional, political and user/public views
recognises importance of knowledge available from those who have been involved in local service
what are some limitations/problems of a corporate approach to HNAs?
- can be difficult to distinguish between need and demand e.g. do they NEED experimental drugs, like the Charlie Gard case
- groups may have vested interests!
- may be influenced by political agendas
- dominant personalities might have undue influence
what groups of people should a corporate approach HNA ideally talk to?
patients, trust managers, doctors, nurses, public health practitioners, commissioning managers, voluntary organisations, community health councils
what are the components of Donabedian’s framework for health service evaluation?
Structure
Process
[Output]
Outcome
NB - outputs usually classified under process but was originally separate
explain the three different components of the framework for health service evaluation?
structure - what is there i.e. buildings, staff, equipment e.g. number of ICU beds per 1000 population
process - what is done e.g. number of patients seen in A&E, what the process they go through is (e.g. where and when seen, who triaged, how is priority assessed), no. ops performed (might be classed as outputs)
Outcome - classification of health outcomes by mortality, morbidity, QoL/PROMs, patient satisfaction
what are some issues associated with using health outcomes in evaluation of healthcare services?
- link between health service provided and health outcome may be difficult to establish - lots of other factors in play
- time lag between service provided and outcome may be long e.g. childhood health eating and T2DM as older adult
- large sample sizes needed for statistically significant effects
- might not have the data
- issues with data quality
what are Maxwell’s Dimensions of Quality used to assess health care quality?
Effectiveness
Efficiency
Equity
Acceptability
Accessibility
Appropriateness (relevance)
briefly explain each of Maxwell’s Dimensions of Quality
Effectiveness - does the intervention produce desired effect?
Efficiency - is the output maximised for given input?
Equity - are patients being treated fairly?
Acceptability - how acceptable is the service offered to the people needing it?
Accessibility - is the service provided? geographical access, costs for patients, waiting times
Appropriateness - is the right treatment being given to the right people at the right time?
give some examples of how quantitative and qualitative methods can be used in health service evaluations
qual - consulting stakeholder (e.g. staff, patients, carers, commissioners) - observation, interviews, focus groups
quant - routine data (e.g. hospital admissions, mortality), review of records, surveys
explain the general framework for how a health service evaluation is laid out
- define what the service is
- what are the aims/objectives of service?
- framework - structure, process, outcome ± dimensions of quality
- methodology used/to be used (quant/qual/mixed methods)
- results, conclusions and recommendations
what is health psychology?
emphasises role of psychological factors in the cause, progression and consequences of health and illness.
- aims to put theory into practice by promoting healthy behaviours and preventing illness
what are the 3 main categories of health behaviour?
health behaviour - behaviour aimed to prevent disease e.g. healthy eating
illness behaviour - a behaviour aimed to seek remedy e.g. going to the doctor
sick role behaviour - any activity aimed at getting well e.g. taking prescribed medications
what are health damaging/impairing behaviours vs health promoting?
damaging e.g. smoking, alcohol use, sun exposure, unprotected sex
promoting - exercise, health eating, vaccinations
what is health promotion?
the process of enabling people to exert control over the determinants of health, thereby improving health
give some examples of health promotion interventions
health promotion/awareness campaigns - Change 4 Life, 4 a days, Stoptober, Sober October
campaigns promoting screening and immunisations - cervical smear, MMR vaccine
what are the different levels a health promotion intervention can impact? e.g. of brief primary care intervention aimed at reducing alcohol consumption among individuals
1) individual behaviour - level of consumption, individual health outcomes, incidence domestic violence
2) local community - local alcohol sales, alcohol-related crime, A&E attendances
3) population level - national sales/consumption, national alcohol-related crime/A&E etc
what factors can influence an individuals perception of risk?
1) lack of personal experience with the problem
2) belief that it’s preventable by personal action
3) belief that if it’s not happened now, it’s not likely to
4) belief that the problem is infrequent
individuals continue to practice health damaging behaviour due to inaccurate perceptions of risk and susceptibility
e.g. “my dad smoked 40 a day from the age of 14 and lived to 102 - why should I bother quitting?”
why might an individual continue to practice health damaging behaviours?
- inaccurate perceptions of risk/susceptibility
- health beliefs
- situational rationality
- culture variability
- socioeconomic factors
- stress
- age
what are the 8 components of the NICE guidance on behaviour change?
1) planning interventions
2) assessing the social context
3) education and training
4) individual-level interventions
5) community-level interventions
6) population-level interventions
7) evaluating effectiveness
8) assessing cost-effectiveness
what does NICE recommend for doctors helping individuals to change their health behaviours?
- work with your patient’s priorities
- aim for easy changes over time
- set and record goals
- plan explicit coping strategies
- review progress regularly
- remember the public health impact of lots of doctors making small differences to individuals
list some models/theories of behaviour change
1) health belief model
2) theory of planned behaviour
3) stages of change/transtheoretical model
4) social normals theory
5) motivational interviewing
6) social marketing
7) nudging (choice architecture)
8) financial incentives
explain the health belief model of behaviour change
individuals will change if they:
- believe they’re susceptible to the condition in question
- believe that it has serious consequences
- believe that taking action reduces susceptibility
- believe that the benefits of taking action outweigh the costs
model says all of the above interact with health motivation (how much they care about being healthy) and cues to action to determine the likelihood of action
what are ‘cues to action’ in the context of the health belief model of behaviour change?
can be internal/external cues - just something which triggers action e.g. brief advice on smoking cessation from a GP
unique component of the HBM
not always necessary for behaviour change to occur though
give some limitations/critique of the health beliefs model of behaviour change
- alternative factors may predict health behaviour e.g. outcome expectant or self-efficacy (belief in ability to carry out the preventative behaviour)
- as a cognitive based model, doesn’t account for influences of emotions on behaviour
- does not differentiate between first time and repeat behaviour
which factor of the health beliefs model of behaviour change has been demonstrated to be most important?
perceived barriers
briefly explain the theory of planned behaviour model of behaviour change
- best predictor of behaviour is ‘intention’ e.g. I intend to quit smoking.
intention determined by: - person’s attitude to the behaviour
- perceived social pressure to undertake the behaviour, or subjective norms
- person’s appraisal of their ability to perform the behaviour, or their perceived behavioural control
what 3 things are most important in determining an individuals intention to change, as described in the theory of planned behaviour?
person’s attitude to the behaviour
the subjective norm (perceived social pressure to undertake the behaviour)
perceived behavioural control - whether they believe they’re able to change the behaviour
what 5 things can we attempt to influence when helping people to act on their intentions (theory of planned behaviour)?
- perceived control
- anticipated regret
- preparatory actions
- implementation intentions
- relevance to self
give some criticisms of the theory of planned behaviour
- lack of temporal element, lack of direction or causality
- rational choice model - ignores emotions which can disrupt our rational decision making
- doesn’t explain how attitudes, intentions and perceived behavioural control interact
what are the 5 stages in the transtheoretical (or stages of change) model of health behaviour?
pre-contemplation contemplation preparation action maintenance
(relapse)
give some advantages to the transtheoretical model of health behaviour change
- acknowledges individual stages of readiness - can tailor interventions
- accounts for relapse
- some temporal element (although arbitrary)
give some critiques of the transtheoretical model of health behaviour change
- not everyone goes through each stage in sequence, can skip some, can go back and forward
- change might be more of a continuum than discrete stages
- doesn’t take into account values, habits, culture, social and economic factors
what is motivational interviewing?
a counselling approach for initiating behaviour change by resolving ambivalence
what is nudge theory?
‘nudge’ the environment to make the best option the easiest e.g. opt-out pensions, placing fruit by check outs
give some different types of determinants of health
- genes
- environment - physical and socioeconomic
- lifestyle
- healthcare
explain equity vs equality
equity is about what is fair and just, equality is concerned with equal shares
equity = giving everyone what they need to succeed on the same level
equality = treating everyone the same
what are the three domains of public health and can you give examples of each?
1) health improvement - inequalities, education, housing etc
2) health protection - infectious diseases, chemicals, radiation, emergency response
3) improving services - clinical effectiveness, efficiency, service planning etc
what factors can influence health inequalities?
PROGRESS Place of residence (rural, urban etc) Race or ethnicity Occupation Gender Religion Education Socioeconomic status Social capital or resources
explain the difference between horizontal and vertical equity
horizontal = equal treatment for equal need vertical = unequal treatment for unequal need
e.g. horizontal - all else being equal, everyone with pneumonia should receive the same treatment.
vertical - individuals with pneumonia deserve different treatment from those with a common cold
vertical - areas with poorer health may need higher expenditure on health services
list some different forms of health equity
equal expenditure for equal need equal access for equal need equal utilisation for equal need equal health care outcomes for equal need equal health
listed top to bottom in order of what is more feasible to actually influence - can easily (ish) influence how much is spent on healthcare, but how easy is it to make sure everyone has completely equal health?
what areas might you assess when examining health equity?
- supply of health care
- access to health care
- utilisation of health care
- health care outcomes
- health status
- resource allocation
- wider determinants of health in the area being examined
typically you’d assess inequality, then decide if inequitable - inequalities need to be justified, but remember that equality may not be equitable (e.g. people of all SE classes using same no. GP appts per year - equal utilisation, but likely there’s unequal need!)
NHS likes to view equity as equal access for equal need (as harder to control whether patients actually use the services available! e.g. STI testing) - equity assessments should measure utilisation as well.
what is health improvement?
domain of public health concerned with societal interventions aimed at preventing disease, promoting health, and reducing inequalities
not primarily health services - things like education, housing, employment
what is health protection?
domain of public health concerned with measures to control infectious disease risks and environmental hazards
what is ‘improving health care services’?
domain of public health concerned with organisation and delivery of safe, high quality services for prevention, treatment and cure
explain the difference between a cluster and an outbreak
cluster = aggregation of cases (may or may not be linked)
outbreak = more cases of disease than normally expected, within a specific place or group of people over a given period of time
needs 2 or more cases linked through common exposure/location
OR single case of rare/serious disease e.g. rabies, polio, diphtheria
confirmed outbreak is when the case has been confirmed through investigation
define food poisoning. what actions should be taken if there’s an outbreak?
‘any disease of an infectious or toxic nature caused by, or thought to be caused by, the consumption of food/water’
includes illness caused by toxic chemicals if transported in food.
actions:
- identify affected cohort
- identify source
- ?close restaurant
- people sampling, food sampling, questionnaires (to detect cause)
in what 4 different ways can something go wrong in terms of patient care?
- human error
- neglect
- poor performance
- misconduct
can be one or a combo of these
briefly explain the swiss cheese model of ‘error’ as it relates to patient care
basically there lots of levels of defence - the slices of cheese - systems put in place to prevent error e.g. separate appts, fridges etc for different chemo drugs
the holes in the cheese = latent conditions leading to error e.g. patient misses first appt so decide to give drugs together (poor management decision), also poor design or procedures
active errors = mistakes made that then means all the little holes line up and there’s an error in patient care
what is neglect?
care falling below accepted standard
results in frequent minor mistakes
develops from culture of not caring
can involve neglect of necessary/personal care, safeguarding neglected, medical care not given
Mid-Staffs!!!
what is “poor performance” - as one of the four things that can cause errors?
problem of attitude - laziness, lateness, not caring
failure to learn from mistakes or listen to advice of others
affects patient care
what is misconduct - as one of the four things that can cause errors?
deliberate harm - can be minor (e.g. rough handling)
lack of candour - hiding own/others mistakes, ignoring mistakes (hoping they’ll go away!), altering medical records, failure to report concerns
inappropriate relationships - patients, relatives, supervisors
fraud/theft - false expense claims, false ‘sick’ days, drug and alcohol problems
what is “medical negligence”?
legal entity - outcome of a court case
NOT a crime - civil claim for damages - you pay these, rather than go to prison
you can be found liable (but can’t be found guilty)
this is why we have MDU/MPS
what are the four qus that have to be asked to demonstrate medical negligence?
- did this dr have a duty of care to the patient?
- was their a breach in the duty of care?
- did the patient come to some harm? - on the patien
- did the breach in duty of care cause the harm?
how is ‘duty of care’ defined in medical negligence cases?
usually pretty clear
all patients - often also relatives when on the ward etc (fair of them to expect you to help if they arrested)
sometimes includes fellow passengers/passers-by
if you offer medical advice, you accept a duty of care - even if student!
how is a ‘breach in duty of care’ defined in medical negligence cases? name the two tests
Bolam test - would a group of reasonable drs do the same?
Bolitho test - would it be reasonable of them to do so?
best defence is NICE guidelines, local or college policies
how is it established in a medical negligence case whether a patient came to harm and if breach caused it?
onus is on patient
recognised complications not negligent e.g. wound infections
standard of proof is ‘on the balance of probabilities’ i.e. it is more likely than not that this breach in duty of care led to this harm (lower standard than criminal ‘beyond reasonable doubt’)
how does the court decide what damages to award if a patient wins a medical negligence case?
considers:
- loss of income
- costs of care required as a result
- pain and suffering
in USA they also award punitive damages i.e. to punish the doctor
what is intuitive decision making? advantages/disadvantages
‘ability to understand something instantly without cognitive reasoning’
advantages - fast and frugal
disadvantages - prone to biases, cognitively overpower (i.e. you struggle to override it once you’ve linked one answer/diagnosis)
what are ‘heuritics’?
cognitive short cuts - availability, anchoring and adjustment etc
e.g. people overestimate risk of death from plane crash after there’s been one in the news
what 4 different types of bias/error can result from intuitive decision making?
error of over-attachment - confirmation bias (running tests to get confirmation of the diagnosis you’ve decided it is, rather than running full investigations), premature closure, sunk costs
error due to inherited thinking - diagnosis momentum (e.g. handed over as ?something, stay focussed on that), framing effect
error due to failure to consider alternatives - search satisfaction, multiple alternatives bias
errors in prevalence perception or estimation - availability bias, base-rate neglect, Gambler’s fallacy
what is analytical decision making? advantages/disadvantages
using evidence based medicine to make decisions - based on known odds/values
adv. - accurate and reliable
dis - slow (patients waiting), resource intensive, cognitively demanding
how do we reduce risks associated with intuitive decision making?
1) decision environment/processes - reduce distractions, having to make multiple decisions at once, reduce interruptions etc
2) personal debiasing - acknowledging them, acknowledging our limitations (e.g. recognising when we’re distracted by personal issues or just being hungry), also consciously trying to slow cognition and think things through
3) structural debiasing - training in dual process theory, cognitive strategies to reduce bias, checklists, group decision making (MDT, ward rounds)
what is dual process theory?
combining intuitive cognition with analytical thinking - reduces labourious process of analytical thinking, but also reduces biases associated with intuitive decision making
list the 10 basic types of human error and give brief explanation of each
1) sloth - not bothering to check results/complete exam/document fully etc
2) fixation/loss of perspective - focussed on a specific diagnosis early, so miss later signs
3) communication breakdown - unclear instructions/plans, ignoring others opinions
4) poor team working - poor direction, independent working, some members of team out of depth
5) playing the odds - choosing common and dismissing rare event
6) bravado - working beyond confidence/without supervision
7) ignorance - lack of knowledge, don’t know what you don’t know
8) mis-triage - over/under estimating seriousness of situation
9) lack of skill - lack of appropriate skills/teaching/practice
10) system error - environmental, tech, equipment or organisation features
list some benefits of doctors using social media
- establishing wider and more diverse social and professional networks
- engaging with the public and colleagues in debates
- facilitating public access to accurate health info
- improving patient access to services
list some risks of doctors using social media
- loss of personal privacy
- potential breaches of confidentiality
- online behaviour that might be perceived as unprofessional, offensive or inappropriate by others
- risks of posts being reported by media or sent to employers
what are never events?
events that cause harm/death to patients
data on them published - shows gaps in provision of quality care, can affect reputation of Trust
have financial penalties
prompt visits by external agencies e.g. CQC, comissioners
give some examples of never events
surgery - wrong site/implant, retained foreign object
medications - wrong preparation, wrong route, OD etc
mental health - suicide
general health - falls from windows, entrapment in bed rails etc
maternity - PPH deaths
what is culture?
“socially transmitted pattern of shared meanings by which people communicate, perpetuate and develop their knowledge and attitudes about life”
“the collective programming of mind which distinguishes members of one group/category of people from another”
it informs our internal worldview (way we interpret things and events)
what is medical ethnocentrism?
belief that health care providers, educated and socialised within a bio-med context have a superior value system and correct, accurate approach to healthcare (basically - drs etc know best)
bad for patients, particularly for communication - might mean patients refuse to communicate their beliefs/behaviours for fear of negative reaction, can mean significant info not obtained
what is individual culture based on?
- heritage e.g. language, country of origin, ethnicity, family etc
- individual circumstances e.g. gender, age, SE status
- personal choice e.g. religion, lifestyle
dynamic entity
more than what we can see (iceberg model of culture)
what are stereotypes?
generalisations about “typical” characteristics of members of a group - and we have a natural tendency to confirm stereotypes by looking for info consistent with it
what is prejudice?
holding a particular attitude towards another person based solely on their membership of a group.
there are cognitive and affective components - cognitive involves stereotypes, affective involves negative or positive feelings towards someone
what is discrimination?
actual positive or negative actions towards the objects of prejudice
(rather than just holding the attitude)
list some challenges of working across cultural distance
- effortful - energising/exhausting
- assumptions more likely to be wrong
- humour/rapport
- language
- different expectations of roles for dr and patient
- different explanatory model
the greater the cultural distance, the more likely it is that any assumptions you make will be wrong - so you have to ask more questions of both patient and of yourself
give some basic info on the human rights act
- forms part of decision making processes when making decisions about people’s rights - part of all policy making
- states that all people are entitled to certain rights, regardless of age, sex, religion etc etc
rights frequently involved in healthcare - right to life, right to be free from inhuman and degrading treatment, right to respect for privacy and family life, right to marry and found a family
how does the WHO constitution define health?
health is the state of complete physical, mental and social wellbeing and not merely the absence of disease or infirmity … the highest attainable level of health is the fundamental right of every human being
explain the difference between absolute rights and limited/qualified rights
absolute rights apply to everyone, always e.g. prohibition of slavery
limited/qualified rights - limited under explicit and finite circumstances e.g. right to liberty can be restricted to protect public safety
is there a right to medical treatment dictated by human rights?
there’s a right to life, but can’t always demand right to healthcare
article 2 states - positive obligation upon the state to take appropriate steps to safeguard life - but cannot impose an impossible or disproportionate burden on authorities
e.g. we have human right to family life, but doesn’t mean every patient has right to demand IVF
what does the NHS act 2006 section 3 say about obligation to fund healthcare?
no absolute duty on secretary of state to provide funds for NHS, only obliged/duty to provide services to such extent as he considers necessary to meet all reasonable requirements
god knows what that means
what is a judicial review?
opportunity for an individual to challenge the exercise of power by a public body - i.e. patient/groups of patients could challenge local decision makers as being ‘unjust’ for not providing certain healthcare
what are the exceptionality criteria?
where local authorities have policy regarding healthcare provision, but can also make exceptions at their discretion - in ‘exceptional circumstances’, and they’re able to leave those circumstances undefined
BUT this can’t breach human rights e.g. can’t refuse treatment cos of a patient’s age
give some reasons why there’s an increasing need to ration healthcare
- shift from acute illness to chronic long term diseases
- normal physiological events becoming medicalised
- increase in choice and increase in expensive drugs
also - real term NHS spending not increasing annually by as much - push for more productivity and efficiency
list some different principles used to determine allocation of healthcare resources, and give brief explanation of each
1) egalitarian principles - same principles that NHS founded on - emphasises providing all care necessary and appropriate to each person - not necessarily same treatment e.g. someone with T1DM costs a lot more than healthy person - equal access
2) maximising principle - same as utilitarianism - act to maximise public utility - but how do we decide what conditions achieve this really?
3) libertarian principles - state that each is responsible for their own health, wellbeing and fulfilment of their life plan - must be willing to invest in their health and pay cost of consequences e.g. German health incentive schemes - everyone contributes % of income, and there’s incentives for positive health behaviour change e.g. bonuses for participating in screening or weight reduction etc, co-payment increases when non-compliance
what are the four fundamental ethical principles?
1) respect to autonomy - respect people’s wishes
2) non maleficence - do no harm
3) beneficence - obliged to bring about good with all actions
4) justice - treat everyone equally
what is utilitarianism?
ethical principle which says best action is the one that maximises utility (utility defined various ways, just generally means best option for total overall best outcome)
what is deontology?
ethical theory that the morality of an action is determined based on whether that action itself is right or wrong - not on consequences of the action (that would be consequentialism)
what is virtue ethics?
states that morality of action is defined by how moral the person doing it is - an individual’s character is important rather than the act itself
give an example of healthcare that is needed but not demanded or supplied
intensive weight loss support
sexual education in conservative cultures
give an example of healthcare that is needed and demanded, but not supplied
local hospitals (e.g. cottage hospitals), local A&E departments being closed, OPD appts (long waiting lists = not enough supply)
give an example of healthcare that is demanded, but not needed or supplied
specialist services/treatments e.g. Charlie Gard, new cancer drugs.
antibiotics for viral illness - although sometimes supplied!
give an example of healthcare that is supplied, but not demanded or needed
repeat prescriptions e.g. for salbutamol inhalers, that are no longer used
paracetamol prescriptions
a lot of health promotion
give an example of healthcare that is needed, demanded and supplied
the holy grail!
free contraception - usually
give an example of healthcare that is demanded and supplied, but not needed
cosmetic surgery
abx for viral illness
give an example of healthcare that is needed and supplied but not demanded
smoking cessation/alcohol reduction services
