Screenings in Medicine

Question 1

True Positive

Answer 1

Test correctly reports a positive result in a patient that acutes DOES have the disease

Question 2

True Negative

Answer 2

Test correctly reports negative result in a patient DOES NOT have the disease

Question 3

False Positive

Answer 3

Test incorrectly reports a positive result in a patient that actually DOES NOT have the disease

Question 4

False Negative

Answer 4

Test incorrectly reports a negative result in a patient that actually DOES have the disease

Question 5

Sensitivity

Answer 5

How well a test can detect presence of disease when in fact disease is PRESENT… Positivity of test in the Diseased

Question 6

A sensitive test has a low false negative rate

Answer 6

Proportion of time that a Test is positive in a patient that DOES have the disease

Question 7

Sensitivity calculation

Answer 7

Sensitivity= TP/(TP+FN)x100%

Question 8

Specificity

Answer 8

How well a test can detect absence of disease when in fact the disease is absent ….. negativity of test in the healthy

Question 9

A specific test has a low false positive rate

Answer 9

Proportion of time that a test is NEGATIVE in a paitent that does not have the diesease

Question 10

Specificty calculation=

Answer 10

Specificity=TN/(TN+FP)x100%

Question 11

Positive Predictive Value(PPV)

Answer 11

How accurately a positive test predicts the presence of diesee. Percentage of TP’s in patients with a positive test (correct predition)

Question 12

PPV=

Answer 12

TP/(TP+FP)x100%

Question 13

Negative Predicitive Value

Answer 13

How accurately a negative test predicts the absence of diease.. Percentage of TN’s in patinents with a negative test ( Correct predition)

Question 14

NPV=

Answer 14

NPV=TN/(TN+FN)x100%

Question 15

Daignostic Accurace(DA) or Diagnositc Precision(DP)

Answer 15

Proportion of time that a patient is correctly identified as either having a diesase or not having a diesase with a positive or negative test

Question 16

DA/DP=

Answer 16

=(TP+TN)/(TP+FP+FN+TN) x 100%

Question 17

Likelihood Ratios

Answer 17

Probablity of a given test result for a person with the disease / probabiltiy of the same test reslut for a person without the diesase…. can be done for positive or negative

Question 18

LR+….. should be >10 to demonstrate the test is most beneficial

Answer 18

Probabilty of a positive test in the presence of diesease/ probabilty of a positive test in the absence of diesase…. sensitivity/(1-specificity(C BOX))

Question 19

LR-… should be <0,1 to demonstrate that the test is most beneficial

Answer 19

Probabilty of anegative test in the presnence of diesase /probabilty of a negative test in the absence of disease
= (1-sensitivity)/specificity

Question 20

a useless test

Answer 20

a test that gives you equal probablity of having a negative or positive test

Question 21

Validity

Answer 21

ability to accurately discern btw those that DO have the disease and those that DONOT have the disease “telling the truth”

Question 22

Internal validity

Answer 22

extent to which results accurately reflect the true situation of the study population (sample)

Question 23

external validity

Answer 23

extent to which results are applicaple to other populations not included in the original study (how similar were study participants to your patients?)… generalizability

Question 24

Reliability

Answer 24

ability of a test to give the SAME results on repeated uses… reproducability/ consistency…. A valid test is always reliable, yet a reliable test is not always valid