screening Flashcards
what is the purpose of screening
spot the individuals who are more likely to have a disease.
what is sensitivity
Sensitivity of a test is the probability of a person with the disease obtaining a positive test result
total number of people with the disease screened
A measure of how well a test picks up those with a disease.
what is specificity
Specificity of a test is the probability of a person without the disease testing negative
true negative results
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total number of people screened
It is a measure of how well a test recognises those without the disease.
what factors make a screening programme
The condition should be an important problem
There should be an acceptable treatment
Facilities for diagnosis and treatment should be available
There should be a recognised latent or early stage
The natural history of the disease should be known
There should be a suitable test
The test should be acceptable to the population
There should be an agreed policy on whom to treat as patients
The cost of case finding should be economically balanced in relation to the possible expenditure as a whole
Case findings should be a continuous process- not once and for all
whats a positive predictive value
The proportion of people with a positive test result who actually have the disease
what is a negative predictive value
The proportion of people without the disease who are correctly excluded by the screening test
how does prevalence affect false results in a screening programme
state how it would affects positive predictive and negative predictive values
If the prevalence of a disease is high, the incidence of false positives will fall. The positive predictive value therefore increases and the negative predictive value falls.
what are the pros of screening
Prevent suffering
Early identification being beneficial
Early treatment is cheaper
Patient satisfaction tends to be high
