Diagnostic Tests Flashcards
what are diagnostic tests for
helping you rule in or out particular medical and physical problems in order to reach a diagnosis
what signals PTs when doing a special test
provocation of symptoms
pain in an area
abnormal signs or symptoms
why are diagnostic tests important
informing patient care and evaluating treatment benefit
how do diagnostic tests inform patient care
accurate diagnosis informs the selection of the most appropriate treatment
why are diagnostic tests for PTs
primary care providers that may be in a situation to make a diagnosis
what are three things that you want to know about a special test
are they reproducible/accurate
how often do they affect clinical decision making
do they have adverse effects
highly sensitive tests will
produce many true positives and false positives
highly specific tests will produce
less false positives and more true negatives
what is a true positive
diagnostic test is positive in those with the diagnosis
what is a true negative
diagnostic is negative in those without the diagnosis
what is a false positive
diagnostic test is positive in those without the diagnosis
what is a false negative
diagnostic is negative in those who have the diagnosis
diagnostic tests that have high sensitivity are good at
identifying true positives in a large sample
also will produce many false positives due to low trigger threshold
what are highly sensitive tests used for
ruling out a problem or rejecting possible diagnosis
highly specific tests identify ____
identifying true negatives due to high trigger threshold
also will produce many false negatives
what are highly specific tests good for
rule in a problem or confirm a diagnosis
when is a diagnostic test result clinically useful
test with high sensitivity having a negative result
test with high specificity having a positive result
what is a positive likelihood ratio
ratio of the likelihood of positive result in someone with the disease to the likelihood of that result in someone without the disease
what # of likelihood ratio means what
2-5 = small likelihood of positive
5-10 = moderate likelihood of positive
>10 = conclusive for confirming patho
what is a negative likelihood ratio
ratio of the likelihood of a negative result in someone with the disease to that of the result in someone without the disease
what negative likelihood ratio means what
0.2-0.5 = small likelihood of absence
0.1-0.2 = moderate likelihood of abs
<0.1 = conclusive in the absence of patho
what is the positive predictive value
probability that the patient truly has disease if there is a positive diagnostic test
how to calculate ppv
of true pos + # of false pos
number of true positives / (number of true positives + number of false positives)
what is negative predictive value
probability that the patient does not have the disease if they have a negative test
