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Epidemiology Exam 2 > Screenings in Medicine > Flashcards

Flashcards in Screenings in Medicine Deck (38)
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1

What are the two questions that a patient should ask the physician when a medical screening is recommended?

1. how accurate the screening test is
2/ How confident the doc is about the prediction of the disease

2

What are the 4 outcomes to a screening?

true positive
false positive
true negative
false negative

3

Define true positive

the test correctly reports a positive test result in a patient that actually has the disease

4

Define True negative

the test correctly reports a negative test result in a patient that does not have the disease

5

Which portion of the 2X2 table does a true positive fall under?

A

6

What portion of the 2X2 table does a true negative fall under?

D

7

Define False positive

A test incorrectly reports a positive result in a patient that does not have the disease

8

Define a False Negative

A test incorrectly reports a negative test result in a patient that does have the disease

9

Which portion of the 2X2 table does the false positive fall under?

B

10

Which portion of the 2X2 table does the false negative fall under?

C

11

What are the two aspects that describes the accuracy of the screening test?

Sensitivity and Specificity

12

Define sensitivity

How well a test can detect the presence of disease wen the disease is present

13

What is the equation for sensitivity?

TP/(TP+FN) X 100% LOOK AT ALL DISEASED

14

Define Specificity

How well a test can detect the absence of disease when in fact the disease is absent

15

What is the equation for specificity?

TN/TN+FP X 100% (ALL NOT DISEASED)

16

What are the two elements that represent the doctors confidence?

Positive predictive value and negative predictive value

17

Define positive predictive value

How accurately a positive test predicts the presence of disease

18

What is the equation of positive predictive value?

PVV= TP/ (TP+FP) x 100% (ALL POSITIVE TESTS)

19

Define negative predictive value

How accurately a negative test predicts the absence of disease

20

What is the equation for the negative predictive value

NPV=TN/(TN+FN) x 100%

21

What happens to the PPV as the prevalence gets closer to 100%?

It sky rockets to 100% as well

WHY? because tests will increase with more disease

22

Will sensitivity and specificity change as the prevalence gets closer to 100%?

No they will not because the TEST DOES NOT CHANGE

23

Define diagnostic accuracy

the proportion of total screenings that a patient is correctly identified as either having a disease (TP) or not having a disease (TN) with either a positive or a negative test, respectively

24

What is the equation for diagnostic accuracy?

(TP+TN)/ (TP+FN+FP+TN)

25

Define the likelihood ratio.

the ratio of the probability of a given test result for a person with disease OVER the probability of the same test result for a person WITHOUT the disease

26

What is in the numerator for the likelihood ratio?

the people with disease

27

Define the likelihood ratio positive

The probability of a positive test in the presence of disease over the probability of a positive test in the absence of disease

28

Using the letters from the 2X2 table, what is the equation for the likelihood ratio positive?

(A/A+C)/(B/B+D)

29

Define the likelihood ratio negative

The probability of a negative test in the presence of disease over the probability of a negative test in the absence of disease

30

Using the letters from the 2X2 table, what is the equation for the likelihood ratio negative?

(C/A+C)/(D/B+D)