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Epidemiology 3 > Class 26-28: Screenings In medicine > Flashcards

Class 26-28: Screenings In medicine Flashcards

1
Q

What’re 2 questions pt.’s should always ask their md’s?

A

How accurate is the screening test you’re recommending?

Based on test results, how confident will you be in your prediction of whether I do or don’t have the Dz?

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2
Q

Sensitivity and specificity looks at which question?

A

How accurate is the screening test?

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3
Q

4 screening outcomes:

A

True positive
True negative

False positive
False negative

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4
Q

When someone w/ Dz is tested positive

Box A

A

True positive

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5
Q

When someone w/o Dz is tested negative

Box D

A

True negative

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6
Q

Rows on 2x2 table for medical screenings:

A

Positive
Negative

—instead of yes/no

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7
Q

True positive is in which box for 2x2?

A

Box A

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8
Q

True negative is in which box for 2x2?

A

Box D

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9
Q

When someone w/ Dz is tested negative

Box C

A

False negative

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10
Q

When someone w/o Dz tests positive

A

False positive

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11
Q

False positive falls in which box of 2x2?

A

Box B

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12
Q

False Negative is in which box for 2x2?

A

Box C

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13
Q

How well a test can detect presence of Dz:

A

Sensitivity

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14
Q

Positivity of test in the diseased

Rule out Dz

A

Sensitivity

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15
Q

Looks at the % of true positives

A

Sensitivity

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16
Q

Proportion of time that a test is POSITIVE in a patient that DOES have the Dz

A

Sensitivity

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17
Q

If a test is either highly-sensitive that test is said to have a low:

A

A low false-negative rate

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18
Q

How to calc sensitivity?

A

TP /
TP + FN

OR

TP /
All Dz

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19
Q

How well a test can detect absence of disease when Dz is absent :

A

Specificity

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20
Q

Negativity of test in the healthy

Rule out Dz

A

Specificity

21
Q

Proportion of time that a test is NEGATIVE in a pt. That does NOT have Dz

A

Specificity

22
Q

A highly specific test is said o have a low…

A

False positive rate

23
Q

Looks at % of time ppl w/o Dx get a negative test:

A

Specificity

24
Q

How to calc specificity:

A

TN /
TN + FP

OR

TN /
All not Dz

25
Q

Sensitivity is asso. W/ which box on 2x2?

A

Box A

26
Q

Specificity is asso. W/ which box on 2x2?

A

Box D

27
Q

Positive predictive value and negative predictive value answer which MD question?

A

How confident are you in test results?

28
Q

How accurately a positive test predicts the PRESENCE of Dz

A

PPV

29
Q

% of TP’s in pt.’s w/ a positive test (correct prediction)

A

PPV

Also called PVP-Predictive value-positive

30
Q

How to calc PPV?

A

TP /
TP + FP

OR

TP /
All positive tests

31
Q

PPV is asso. W/ which box on 2x2?

A

Box A

32
Q

NPV is asso. W/ which box on 2x2?

A

Box D

33
Q

How accurately a negative test predicts the ABSENCE of Dz

A

Negative predictive value

-NPV

34
Q

% of TN’s in pt.’s w/ a negative test (correct prediction)

A

NPV

Also, called PVN predictive value-negative

35
Q

How to calc NPV?

A

TN /
TN + FN

OR

TN /
All negative tests

36
Q

Proportion of time that a pt. Is correctly identified as either having a Dz or not having a Dz w/ a positive or negative test

A

Diagnostic accuracy (DA) or diagnostic precision (DP)

37
Q

How to calc DA?

A

TP (box A) + TN (box D) / all pt’s

38
Q

Ratio of the probability of a given test result for a person w/ the Dz / probability of the same test result for a person w/o Dz

Can be calc for both + and - results

A

Likelihood ratio (LR)

39
Q

Probability of a + test w/o Dz

A

LR+

40
Q

Probability of a - test w/ Dz / probability of a - test w/o Dz

A

LR-

41
Q

What should LR+ be if beneficial?

A

> 10

42
Q

What should LR- be if beneficial ?

A

<0.1

43
Q

Ability to accurately discern btw those that DO and those that DONT have Dz

A

Validity

44
Q

Extent to which results accurately reflect what was being assessed

A

Internal validity

45
Q

Extent to which results are applicable to other populations

Generalizability

A

External validity

46
Q

Ability of a test to give the same results on repeated uses

Reproducibility

A

Reliability

47
Q

A valid test is always ______, yet a ______ test is not always ________

A

Reliable, reliable, valid

48
Q

Many diagnoses typically have 2 dichotomous outcomes (+,-)

A

Multiple cutoff values

49
Q

For screening test w. Numerical values, we use what for more efficient way to show a relationship btw sensitivity and specificity for tests w/ numerical outcomes?

A

ROCs

Receiver operator curves

Epidemiology 3 (3 decks)

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