Flashcards in Segars: Screenings in Medicine Deck (17)
What does a patient want to be told when they get screened for a disease?
What 2 questions should patients ask their physician when a medical screening test is recommended?
-how accurate is it?
-When the test results are announced, how confident will you be in your prediction of whether I do or don't have the disease?
What is true positive?
-test is positive and the patient does have the disease
What is False positive?
-test is positive but the patient does not have the disease
-pt doesn't have the disease
-but the pt does have the disease
What will the numerator be?
-either box A or D
What is sensitivity and specificity related to?
-the test itself
What does positive or negative predicitive values do?
-predicts the accuracy of diagnosis (based on known test result)
-remember, boxes A and D are the numerators
What is sensitivity
-how well a test can detect preence of disease when in fact it is truly present
-proportion of time that a test is positive in a pt that is known to have the disease
-TP/(everybody that has disease)*100%
What is specificity?
-how well a test can detect absence of disease when in fact it is truly absent
-proportion of time that a test is negative in pt that is known to not have the disease
-TN/(all non-diseased... like TN and FP)*100%
What is a positive predictive value (PPV)?
-how accurately a positive test predicts the presence of disease in a pt with a positive test result
-proportion of true positives in a pt that tests positive (correct prediction)
-PPV=TP/(all positive tests)
What is negative predictive value (NPV)?
-how accurately a negative test predicts the absence of disease ina pr with a negative test result
-proportion of true negatives in a pt that tests negatvie (correct prediction)
-NPV= (TN/(All negative tests))
What is Diagnositc accuracy/diagnostic precision?
-Proportion of patients that are correctly identified as either having truly having disease (TP) or truly not having disease (TN) out of all pts screened
How do we figure out if it is a column total or row total that we will be dealing with?
-with sensitivity or specificty, there will be something about absolute truth... column totals
What is validity?
-getting it right.... telling the truth
-getting it in boxes A and D