Screening Flashcards
Giving a example, why is screening not always a good thing?
Neuroblastoma (childhood cancer of nerve) has a better prognosis if caught early so Japan started screening detecting lots of cases with a good survival rate HOWEVER, death rate remain unchanged as no. presenting above 1 year didn’t change so incidence increased so there was no benefit of screening and 3 deaths as a result of treatment complications for unnecessary treatment in cases that probably would have resolved themselves
What is overdiagnosis and overtreatment?
Overdiagnosis = correct diagnosis of a disease (TP) but the diagnosis is irrelevant because disease will never cause symptoms within the patients life time (found across Medicine but an ethical issue in screening) associated with…
Overtreatment = unnecessary treatment which does not improve health
What is the problem with breast cancer screening?
Unnecessary and potentially harmful cancer treatment i.e. surgery/radiotherapy in some cases
What is the problem with prostate cancer screening?
Most men get it at some point not causing any problems and they will most likely die from other causes so we wouldn’t want to know in screening if this was the case as it would provide unnecessary worry meaning over-treatment would occur and result can also be unclear causing worry (disease reservoir) -> SO its not screened for but they can ask for PSA test if doctor warns of risks/benefits
What is the popularity paradox?
If people get screened, a disease is detected, they are treated and are healthy after they will be happy and promote the screening which will increase over-diagnosis and over-treatment which is why you should be cautious before beginning screening
What is a disease reservoir?
When a person has detectable levels of a disease e.g. prostate, thyroid or breast cancer but it is likely to not cause them any problems in their life so they are at high risk of overdiagnosis/overtreatment if screening occurs
What indicates overdiagnosis and overtreatment is occurring?
If diagnosis has increased of a disease BUT deaths have not changed
What are incidental findings?
Pathologies that are found when carrying out other tests e.g. chest CT that may or may not cause a problem
What does the Wilson and Jungner criteria state for screening to be introduced?
- Condition should be an important health problem (severity rather than commonality)
- Accurate and acceptable test/examination to diagnose condition
- Treatment should be available
- There should be a latent stage of disease and early treatment should be clearly more beneficial than later treatment
- Natural history of disease should be adequately understand
- Agreed policy on who to treat
- Total cost of finding a case should be economically balanced in relation to medical expenditure as a whole
- Case-finding should be a continuous process, not just a “once and for all” project
What screening tests are borderline acceptable to the population?
Cervical: intra-vaginal exam
Colorectal: faeces collection and if a +ve result is found a colonoscopy
What considerations must be taking into account when applying the Wilson and Jungner criteria to screening decisions as stated by UK National Screening Committee (part of PHE)?
How do we define population? How frequently to test? Which test to use? Which results to use? How to gain informed uptake? External pressures
What conditions does the UK screen for in antenatal and newborns?
Downs syndrome Fetal anomaly US Infectious disease in pregnancy Antenatal sickle cell and thalassaemia Newborn and infant physical exam Newborn blood spot Newborn hearing screen
What conditions does the UK screen for in young persons and adults?
AAA Diabetic retinopathy Breast cancer Cervical cancer Bowel cancer
What are the different types of test results that can come back?
TP
FP
TN
FN
What is sensitivity?
Proportion of people who have the disease that the test correctly detects i.e. it doesn’t miss many (FNs)
TP/TP + FN
