HADSOC PART 2 Flashcards
How is disease detected?
spontaneous presentation
opportunistic case finding
screening
Define screening
a sytematic attempt to identify an unrecognised condition via applying tests or asking questions, which can be done rapidly and cheaply, to distinguish between apparently well people who probably have the disease, or its precursor, and those who probably do not have it, and so identify people who are more likely to be helped than harmed by further tests or tment to reduce risk of disease or its complications
what is lead time bias?
example of an evaluation difficulty for screening programmes.
Refers to an early diagnosis falsely appearing to prolong patient survival, with screened patients seemingly surviving longer, when actually they live for same length of time, but spend longer knowing they have the disease, and so only appear to live longer as diagnosed earlier.
why does lead time bias occur?
once screening has detected a disease before the disease is clinically obvious, the finding out of the patient that they have a disease is brought forward and so the length of time told that they have left to live will be longer, than if the disease was only picked up when symptomatic as that would occur years later, and so there would be less time between detection and dying, althought they will still die at the same time, they just spend more time knowing they have the disease.
examples of evaluation of screening programmes difficulties?
lead time bias
length time bias
selection bias
why is finding a disease earlier NOT the primary objective of screening?
giving tment earlier may not improve disease outcome
tment earlier may produce harmful SEs
uneccessary anxiety and depression if find out they have the disease earlier in life and there is nothing that can be done to help them
screening purpose?
give better outcome when compared with finding something in the usual way
risks and benefits of AAA screening?
+ve: reduce risk of death from rupture by 1/2
-ve: coping with anxiety of having small AAA
QOL impaired when tment
tment can be complicated by death
criteria for screening programmes?
disease/condition
test
tment
programme
factors assoc with disease in order to have a screening programme?
important health problem- QOL, early mortality
epidemiology and nat history understood to know what category of people screening would be relevant to, and identify when it should be implemented
must have an early detectable stage
cost-effective primary prevention interventions must have been considered, and where possible implemented to reduce risk of disease develop e.g. quitting smoking to reduce LC risk before LC screening
characteristics of test for use in screening?
simple and safe
precise and valid, validity= sensitivity, specificity, PPV, NPV
acceptable to pop.
distribution of test values in pop. known
agreed cut-off level for when person will class as testing +ve
must be agreed policy on whom to investigate further
which screening programmes lack test acceptability?
colorectal cancer- having to use special toilet paper which is then sent off in the post for assessment
cervical cancer- smear, invasive procedure
characteristics of treatment in order to have a screening programme?
effective evidence based tment available
early tment must be advantageous- so not just bringing fward date of diagnosis, must be something beneficial to outcome by finding disease earlier
agreed policy on whom to treat
clinical management of the condition and patient outcomes should be optimised in H care providers before participation in screening programme
characteristics of the screening programme itself in order for screening to be implemented?
proven effectiveness e.g. RCT data
quality assurance for whole programme and not just test
facilities for counselling
facilities for diagnosis and tment
consider other options e.g. improving tment
opportunity costs- should money spent on screening be used on tment
decisions about parameters should be scientifically justifiable to the public
benefit should oweigh phys and psych harm
issues for patient if +ve screening test, but they don’t have the disease?
uneccessary stress, anxiety, inconvenience- SEs of tment
direct costs
opportunity costs- resources consumed that could be used to treat people who actually have the illness
may be lower uptake of screening in future and greater risk of interval cancer= cancer which appears in interval between screening
issues for patient if -ve screening test, but they do have the disease?
false reassurance
possibly delay presentation with symptoms as patient been convinced by screening that they are at low risk of the disease and so symptoms which they may have associated with the disease and so caused them to present if they hadn’t had screening, they may now choose to ignore as they don’t believe they have the disease
advantages of screening?
produce a better outcome for the patient if the disease is detected early
provide reassurance to those patients who are true -ves
disadvantages of screening?
false +ves: uneccessary anxiety, exposure to tment SEs and invasive diagnostic techniques e.g. CAC- colonoscopy, divert money away from treating those people who actually have the illness
false -ves: inappropriate reassurance, present later with symptoms of disease, not given the diagnostic testing they may benefit from
why is length time bias an evaluation difficulty of screening programmes?
screening better at picking up slow-growing, unthreatening cases than aggressives, fast-growing ones, so disease detectable more likely to have a favourable prognosis, and may have never caused a problem had they not been detected by screeening anyway, and so may be curing those that don’t need curing with false conclusion that screening is beneficial in lengthening lives of those found +ve, when in fact, the disease wouldn’t have shortened their life anyway
why is selection bias an evaluation difficulty of screening programmes?
‘healthy volunteer’ effect- those people who have regular screening are likely to be healthier than the general pop anyway as likely to do other things that protect them from disease.
how could selection bias affected screening programmes be dealed with?
RCT as random allocation to screening programme rather than choice of individual to do something beneficial to their health which is more likely done by healthier people anyway
structural critiques of screening?
victim blaming- people must take responsibility for their own health, are all equally able to do this?
individualising pathology- not addressing underlying material causes of disease e.g. primary interventions, so focused on prevention at an individual level, more we could do at a societal (or structural) level to address some of the material causes
surveillance critiques of screening?
individ and pop increasingly subject to sureveillence
prevention part of wider apparatus of social control?- people requested to present themselves for surveillence
5 Ds of rationing in the NHS?
denial- range of services denied to patients e.g. reversal of sterilisation, infertility tment
deterrent- demands for hcare obstructed e.g. paying for a prescription or dental charges- people deterred from using a resource if they have to pay for it
delay- waiting lists
deflection- GPs deflect demand from secondary care
dilution- e.g. fewer diagnostic tests used or cheaper drugs-generic brand, just doing what you absolutely need
why we need priorities in NHS in terms of resources?
scarcity of resources, so demand outstrips the supply, and resources could be used in other ways
it must be clear and explicit who benefits from public expenditure- ethical reasons
need to be clear about whether spending is worth it
why is demand for NHS resources increasing?
pop demographics- ageing pop
costs of new technology
technological advances
what is implicit rationing?
allocation of resources through individual clinical decisions without the criteria for those decisions being explicit, and hence not based on defined rules of entitlement
what might be the benefit of implicit rationing?
more sensitive to complexity of medical decisions and the needs and personal and cultural preferences of patients
disadvantages of implicit rationing?
open to abuse e.g. not giving a patient tment if you don’t like them
decisions based on perceptions of social deservingness e.g. 2 patients require chemotherapy for their lung cancer, but 1 is smoker and the other a non-smoker, so you give it to the non-smoker
can lead to inequities and discrimination
drs unwilling to engage
define explicit rationing
use of institutional procedures for the systematic allocation of resources within the healthcare system, so use of particular guidelines which have an evidence base behind them which is known
advantages of explicit rationing?
transparent, accoutable
opportunity for debate
use of evidence-based practice
more opportunities for equity in decision making
disadvantages of explicit rationing?
heterogeneity of patients and illnesses very complex patient and professional hostility threat to clinical freedom evidence of patient distress- it's made clear to the patient that a particular drug would likely be very effective for them but you're not going to prescribe it because it is unaffordable