Screening Flashcards
What are the WILSON and JUNGER criteria for screening programmes?
CLEAN, FIT AND PC
COST EFFECTIVE - case finding must be cost effective
LATENT- disease must have a latent stage
EXAM/TEST- available for disease
ACCEPTABLE - Test for disease must be acceptable to the population
NATURAL HISTORY- known for disease
FACILITIES- available for diagnosis and treatment
IMPORTANT - disease
TREATMENT - available
POLICY- for who to treat
CONTINUOUS - case finding must be continuous
What are the two broad divisions of screening
Whole population screening
At risk screening
Give some examples of screening programmes and benefits/risks
Cervical screening, mammography - only affect the person being screened butsaves lives
TB, antenatal HIV - conditions that can be transmitted to others
Genetic conditions - may have ramifications for other family members
Neonatal screening - people unable to give consent for screening
How can we ethically assess screening programmes
BENEFICENCE
NON MALEFICENCE
AUTONOMY
JUSTICE
INFORMED CONSENT- big issue in screening - how much info to give? Also affects other family members
What is overdiagnosis?
Correct diagnosis of a disease but disease will never cause symptoms within a persons lifetime
What is overtreatment?
Unnecessary treatment which does not improve health
Give some examples of UK screening programmes, antenatal and newborn ..
Down syndrome
Newborn hearing
Newborn blood spot
Infectious diseases in pregnancy
Give some examples of UK screening programmes ( young person and adult)
AAA
cervical ca
Bowel ca
Breast ca
Give some examples of bias in screening
Healthy screened effect - people who choose to attend screening tend to be more health conscious so healthier
Lead time bias- screening leads to early diagnosis when a disease is more responsive to treatment and so gives the false appearance that people are living longer because of earlier detection
Length time bias - screening is better at detecting diseases that develop slowly.
What is sensitivity
Measures the proportion of positives correctly identified- those who have the condition who are correctly identified as having the condition
True positives/(true positives+false negatives)
A sensitive test helps to rule out a disease when the test is negative
What is specificity?
Measures the proportion of negatives that are correctly identified - those who do not have the condition who are correctly identified as not having the condition
True negatives/(true negatives+false positives)
A specific test helps to rule a disease in when positive
What is PPV?
Positive predictive value
The proportion of those with positive screening results who have the disease
True positives/(true positives+false positives)
As prevalence decreases, the PPV decreases as there will be more false positives for every true positive
What is NPV?
Negative predictive value
Probability that negatives are truly negatives
True negatives/false negatives+true negatives
