B10 H+S Flashcards
What is sensitivity?
true positives, the proportion of positives that are correctly identified. “will it pick up everyone that has the disease”
sensitivity equation
sensitivity= true positives/ true positives and false negatives (how many are true based on all the people with)
what is specificity?
true negatives, measures the proportion of negatives that are correctly identified. “will it pick up only the people with the disease, thus leaving all the people without the disease”
specificity equation
specificity= true negatives/ true negatives+ false positives (how many are false based on all the people that are false)
what does true positive mean?
test indicates disease when there is a disease
what does true negative mean?
test indicates no disease when no disease
false positive?
says is disease when no disease
positive predictive value?
probability of subjects with positive screening having the disease
negative predictive value?
probability that subjects with a negative screening truly don’t have the disease
Sensitivity test useful when?
when the result is negative- sensitivity rule out or snout. (if sensitivity is high and you are negative, youre likely to be negative)
specificity test useful when?
if the test is positive you can be quite sure that they have the disease- sensitivity rule in or spin.
+ve predictive value calculation?
true positive/ true positive+ false positive
how many people of the positives actually have the disease.
what is likelihood ratio?
likelihood that given test resultwould be expected in a patient with target disorder, compared to likelihood that same reusult would be in patient without target disorder (if +ve result, how likely to have disease?)
things commonly screened for?
Cancers PPD- TB prenatal tests ultrasound- AAA diabetic checks
limitations of screening?
cost and use of medical resources
adverse screening effects
stress and anxiety caused by false positive
