public health Flashcards
what are the 3 domains of public health
health improvement (social interventions to promote health & reduce inequalities)
health protection ( disease control measures & environmental hazards)
health care ( health service delivery & quality)
what are the social determinants of health (x8)
PROGRESS
P- place of residence ( rural, urban etc)
R - race/ethnicity
O-occupation
G-gender
R- religion
E- education
S- socioeconomic status
S - social capital or resources
give an example of horizontal equity
every pneumonia pt deserves equal treatment
horizontal equity - equal treatment for equal need
give an example of vertical equity
areas with poorer health care need higher expenditure on health service /// those with pneumonia deserve different treatment to those with a common cold
vertical equity = unequal treatment for unequal need
what are the 9 sections for the Bradford hill criteria for causation
DR B.C. STACS
D- dose -response
R- reversibility
B- biological plausibility
C - consistency
S - strength of association
T - temporality most important
A- analogy (analogous to other similar research)
C- coherence ( coherent to other information)
S- specificity
associations found in research may be due to a variety of reasons, what re the 5 causes of association
bias
confounding fctors
chance
reverse causality
true association
give an example of information bias
information bias - systematic error in measurement / classification of exposure/outcome
e.g. observer - knows controls/cases
participant - recall bis, reporting bias etc
instrument/ measurement - wrongly calibrated/ diff instruments used etc
define lead time bias
early identification appears to increase survival but doesn’t actually alter outcomes they have a lead on the condition
e.g. pt diagnosed earlier, so “lives longer”
define length time bias
slowly progressing diseases are more likely to be picked up by screening, so screening appears to prolong life
Screening tends to detect disease that is less aggressive (slow growing cancers) because they may remain asymptomatic for longer
More aggressive disease becomes symptomatic more quickly, so breast cancer detected because the patient found a lump is more likely to be a more aggressive type of cancer, which is likely to have a poorer outcome.
so length time bias may falsely suggest that those who have been screened have a better prognosis (rather than because they have a less aggressive form of the disease)
give 2 examples of prospective studies
randomised control trial
cohort studies
give 4 types of retrospective studies
case- control
cross-sectional
case series (multiple cases)
case report / anecdote (1 case)
cross-sectional study
advantages (*3)
disadvantages (x3)
cross-sectional - snap shot
adv
- larger sample size
- rapid
- repeated studies = show change over time
disadv
- risk reverse causality
- disease length bias ( excludes people who recover quickly/ conditions with short recovery
- sample size too small for rarer outcomes
case-control studies
advantages (x2)
disadvantages (x2)
adv
- good for rare outcomes
- rapid
disadv
- selection & information bias
- finding well-matched controls is resource consuming
cohort study
advantages (x3)
disadvantages (x4
prospective longitudinal study ( looks at population w/o a disease, splits group into exposed /not-exposed, observes disease/no disease outcome in both groups)
adv
- can establish causal factors ( reverse causality eliminated as disease not happened yet)
- can follow rare exposures
- data on confounders can be collected prospectively
disadv
- difficult in rare outcomes ( conditions may not develop)
- drop outs
- large sample size required (Expensive & time consuming)
RCT disadvantages (x3)
- ethical - is the exposure/ non-exposure ethical?
- drop outs
- expensive & time consuming
how do cross-sectional and ecological studies differ
cross-sectional - prevalence in one area
ecological - compares areas/ time periods / levels of exposure
health needs assessment. when is it needed?
assessment should be conducted before health intervention is done - systematic method to review health issues facing population
what are the 3 sections of a health needs assessment
Need - ability to benefit from an intervention
demand
supply
give the 4 Bradshaw’s needs
FENC
Felt need (individual perceptions of variation from normal health e.g. can’t walk as far)
Expressed need ( individual seeks help to overcome variation form normal health)
Normative need ( professional defines appropriate intervention for expressed need)
Comparative need (comparison between severity, range of interventions & cost (e.g. pt with worse sx are prioritised for oversubscribed service)
what are the 4 stages of the planning cycle of health needs assessments
needs assessment ( assessing pt)
planning( make plan to improve)
implementation (implement new service )
evaluation (evaluate effect on wellbeing)
health needs assessment - advantages ( x3) and disadvantages (x4) to the epidemiological approach
epidemiological approach = top down
adv
- uses existing data
- provides data (incidence, mortality, morbidity etc)
- can evaluate services by trends over time
disadv
- data quality variable
- data collected may not be that required
- does not consider felt needs/ opinions/experiences of those affected
- reinforces purely biomedical approach
health needs assessment - advantages ( x2) and disadvantages (x4) to the comparative approach
(compares services between sub-groups) - e.g. spacial ( MS pts in north vs south yorkshire) vs social ( MS pts >30 vs <30)
adv
- quick & cheap ( if data available)
- gives measure of relative performance
disadv
- may be difficult to find comparable population
- data may not be available/ high quality
- may not yield what the most appropriate level (e.g. of provision/ utilisation) should be
- may be comparing 2 poor quality services
health needs assessment - advantages ( x3) and disadvantages (x4) to the corporate approach
incorporates views from pts, politicians, press, professionals, commissioners etc (e.g. service may be requested but politicians lower its priority due to costs)
adv
- based on felt & expressed needs of population
- recognises detailed knowledge & experience of those working with the popultion
- wide range of views considered
disadv
- difficult to distinguish need from demand
- groups considered may have vested interests
- may be influenced by political agendas
what are the 3 categories in Donabedian approach to evaluating clinical services
structure (What there is)
process ( what is done)
outcome - the 5 Ds ( death, disease, disability, discomfort, dissatisfaction)
what are the 6 categories to Maxwell’s Dimensions for evaluating clinical services
3Es and 3As
Effectiveness
Efficiency
Equity
Acceptability (e.g. OPs happen@ accetable time of day)
Accessibility
Appropriateness ( given to those who need it )
what is Wrights matrix
the combination of Donabedian’s approach and Maxwell’s dimensions for evaluating clinical services
define incidence
number of new cases during a specific time period divided by the size of the population
(Number of new cases during time period/ Population size) x 100%
define prevalence
number of existing cases in a population at a specific point in time
(Number of existing cases/Population size x 100% )
define relative risk
- Risk in one category relative to another
define relative risk
risk in one category relative to another
relative risk = absolute risk in exposed group/ absolute risk in unexposed group
define absolute risk
proportion of a disease which is specifically due to the exposure
In Crookes (population of 1000), 300 people smoke. 45 of the smokers developed lung cancer. 5 of the non-smokers developed lung cancer
* What is the absolute risk of lung cancer in smokers?
* 45 in 300 = 0.15 = 15% = 15 per 100
define absolute risk difference
aka attributable risk
to find the risk specifically attributable to an outcome: difference between the “naturally occurring” cases and cases in exposed group.
- Risk of lung cancer in smokers = 45/300 = 15%
- Risk of lung cancer in non-smokers = 5/700 = 0.7%
- Attributable risk (risk difference) = (15/100) – (0.7/100) = 14.3/100 = 14.3%
how to calculate NTT
1/attributable risk
- always round up NNT, as a fraction of a person cant be treated
300 people smoke. 45 of the smokers developed lung cancer. 5 of the non-smokers developed lung cancer
* Attributable risk = 14.3%
* NNT = 1/attributable risk = 1/0.143 = 6.99
* So, if 7 people gave up smoking in this population, you would prevent one person getting lung cancer
define point prevalence
no. cases @one time/ total population @same time
period prevalence = no. cases in a period / total no. people in population @same time
cumulative incidence calculation
no. new events or cases of disease/ total no. individuals in the population at risk for a specific time interval.
e.g. proportion of patients who develop postoperative complications within one month of surgery
define cumulative incidence
aka incidence proportion
estimate of the risk that an individual will experience an event or develop a disease during a specified period of time.
calculation for Rate ratio
incidence rate in exposed group/ incidence rate in unexposed group
odds ratio
odds of disease in exposed group/ odds disease in unexposed group
with odds being: probability of getting disease / probability of not getting disease
give 3 disadvantages of screening
- distress/ harm in well individuals
- Detection and treatment of sub-clinical disease
- Preventative interventions that may cause harm to the individual or population
- e.g Increased antibiotic resistance if all moms screened for GBS during pregnancy
define tertiary prevention
trying to slow down the progression of the disease
define the prevention paradox
seatbelts
preventative measure which brings much benefit to the population but offers little to the individual
define sensitivity
proportion of people with the disease who are correctly identified
(true positive)/(true positive +false negative)
aka true positive/ total diseased
sensitivity - correct selection (inclusion)
define specificity
proportion without the disease who are correctly excluded
(true negative)/ (true negative/false positive)
aka true negative / total disease free
specificity - correct exclusion
positive predictive value
proportion of +ve results who actually have disease
(true positive)/ (true positive +false positive)
aka (those who actually have disease)/ (all who received positive result)
negative predictive value
proportion with -ve result who don’t have the disease
(true negative)/(true negative +false negative)
(people w/o disease)/ (people told they don’t have disease)
what are the 4 components of Wilson and Junger’s criteria for a screening programme
the condition (serious, well understood, detectable at early stage)
the treatment (accepted tx, facilities for dx &tx vailable, w/ extreme extra workload)
the test ( suitable, acceptable for pts, establish intervals to repeat it)
the benefits ( policy on who to tx, benefit > cost)