Screenings in Medicine Flashcards
What are two questions that patients should ask physician when a medical screening test is recommended?
- how accurate is the screening test you are about to recommend for me?
- When the test results are announced, how confident will you be in prediction of whether I do or don’t have the disease
What is a true positive positive?
test correctly reports to positive result in a patient that actually does have the disease
What is a true negative?
test correctly reports a negative result in a patient that actually does not have a disease
What is a false positive?
test incorrectly reports a positive result in a patient that actually does not have the disease
What is a false negative?
test incorrectly reports a negative result in a patient that actually does have the disease
What is sensitivity?
how well a test can detect presence of disease when in fact disease is present
What is the sensitivity proportion?
true positive / all diseased x 100
What is specificity?
how well a test can detect absence of disease when in fact the disease is absent
What is the specificity proportion?
true negative / all not disease x 100
What describes the accuracy of prediction of disease based on known test results?
positive predictive values
negative predictive values
What is positive predictive values (PPV)?
how accurately a positive test predicts the presence of disease
What is the PPV proportion?
True positive / all positive tests x 100
What is the negative predictive value (NPV)?
how accurately a negative test predicts the absence of disease
What is the NPV proportion?
True negative / all negative tests x 100
What is diagnostic accuracy/ diagnostic precision (DA/DP)?
proportion of total screenings that a patient is correct identified as either having a disease or not having a disease with either a positive or negative test, respectfully
What is the DA/DP equation?
(true negative + true positive) / (all patients) x 100%
What is likelihood ratios (LR)?
ratio of the probability of a give test result for a person with disease / probability of the same rest result for a person without disease
What is the likelihood ratio positive (LR+)?
probability of a positive test in the presence of disease / probability of a positive test in the absence of disease
What is the LR+ equation?
sensitivity / (1- specificity)
What is likelihood ratio negative (LR-)?
probability of a negative test in the presence of disease / probability of negative test in absence of disease
What is the LR- equation?
(1-sensitivity) / specificity
LR+ should be ____ to demonstrate the test is most beneficial
> 10
LR- should be ____ to demonstrate the rest is most beneficial
<0.1
What is validity?
ability to accurately discern between those that do and those that do not have the disease
