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What Happens to the Performance of a Diagnostic Test when the Disease Prevalence and the Cut-Point Change? PowerPoint PPT Presentation


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What Happens to the Performance of a Diagnostic Test when the Disease Prevalence and the Cut-Point Change?. +. Click on the + or – to alter the prevalence. Click on the + or – to shift the cut-point. Prevalence. Healthy population. Sick population. -. Healthy scores. Pathological scores.

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What Happens to the Performance of a Diagnostic Test when the Disease Prevalence and the Cut-Point Change?

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Slide1 l.jpg

What Happens to the Performance of a Diagnostic Test when the Disease Prevalence and the Cut-Point Change?

+

Click on the + or –to alter the prevalence

Click on the + or –to shift the cut-point

Prevalence

Healthy population

Sick population

-

Healthyscores

Pathologicalscores

Cut-point

-

+

Remember:

PPV = predictive value of a positive test result

NPV = predictive value of a negative test


Slide2 l.jpg

PPV 80/107 74.8%

NPV 275/295 93.2%

Sensitivity 82/100 82%

Specificity 275/300 91.7%

+

Disease + −

+

Test

82

18

25

275

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide3 l.jpg

PPV 73/93 78.5%

NPV 280/307 91.2%

Sensitivity 73/100 73%

Specificity 280/300 93.3%

+

Disease + −

+

Test

73

27

20

280

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


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PPV 70/85 82.4%

NPV 285/315 90.5%

Sensitivity 70/100 70%

Specificity 285/300 95%

+

Disease + −

+

Test

70

30

15

285

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide5 l.jpg

PPV 63/70 86.3%

NPV 290/327 88.7%

Sensitivity 63/100 63%

Specificity 290/300 96.7%

+

Disease + −

+

Test

63

37

10

290

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide6 l.jpg

PPV 52/52 100%

NPV 300/348 86.2%

Sensitivity 52/100 52%

Specificity 300/300 100%

+

Disease + −

+

Test

52

48

0

300

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point


Slide7 l.jpg

PPV 90/135 66.7%

NPV 255/265 96.2%

Sensitivity 90/100 90%

Specificity 255/300 85%

+

Disease + −

+

Test

90

10

45

255

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide8 l.jpg

PPV 95/161 59%

NPV 234/239 97.9%

Sensitivity 95/100 95%

Specificity 234/300 78%

+

Disease + −

+

Test

95

5

66

234

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide9 l.jpg

PPV 100/205 48.8%

NPV 195/195 100%

Sensitivity 100/100 100%

Specificity 195/300 65%

+

Disease + −

+

Test

100

0

105

195

25%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide10 l.jpg

PPV 49/91 53.8%

NPV 458/469 97.7%

Sensitivity 49/60 82%

Specificity 458/500 91.6%

+

Disease + −

+

Test

49

11

42

458

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide11 l.jpg

PPV 44/77 57.1%

NPV 467/483 96.9%

Sensitivity 44/60 73.3%

Specificity 467/500 93.4%

+

Disease + −

+

Test

44

16

33

467

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide12 l.jpg

PPV 42/67 62.7%

NPV 475/493 96.4%

Sensitivity 42/60 70%

Specificity 475/500 95%

+

Disease + −

+

Test

42

18

25

475

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide13 l.jpg

PPV 38/53 71.7%

NPV 485/506 95.8%

Sensitivity 38/60 63.3%

Specificity 485/500 97%

+

Disease + −

+

Test

38

22

15

485

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide14 l.jpg

PPV 31/31 100%

NPV 500/529 94.5%

Sensitivity 31/60 51.7%

Specificity 500/500 100%

+

Disease + −

+

Test

31

29

0

500

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point


Slide15 l.jpg

PPV 54/129 41.9%

NPV 425/431 98.6%

Sensitivity 54/60 90%

Specificity 425/500 85%

+

Disease + −

+

Test

54

6

75

425

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide16 l.jpg

PPV 57/167 34.1%

NPV 390/393 99.2%

Sensitivity 57/60 95%

Specificity 390/500 78%

+

Disease + −

+

Test

57

3

110

390

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide17 l.jpg

PPV 60/235 25.5%

NPV 325/325 100%

Sensitivity 60/60 100%

Specificity 325/500 65%

+

Disease + −

+

Test

60

0

175

325

Prevalence

Healthy population

10%

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide18 l.jpg

PPV 82/90 91%

NPV 92/110 83.6%

Sensitivity 82/100 82%

Specificity 92/100 92%

Disease + −

+

Test

82

18

8

92

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide19 l.jpg

PPV 73/80 91.3%

NPV 93/120 77.5%

Sensitivity 73/100 73%

Specificity 93/100 93%

Disease + −

+

Test

73

27

7

93

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide20 l.jpg

PPV 70/75 93.3%

NPV 95/125 76%

Sensitivity 70/100 70%

Specificity 95/100 95%

Disease + −

+

Test

70

30

5

95

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide21 l.jpg

PPV 63/66 95.5%

NPV 97/134 72.4%

Sensitivity 63/100 63%

Specificity 97/100 97%

Disease + −

+

Test

63

37

3

97

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide22 l.jpg

PPV 52/52 100%

NPV 100/148 67.6%

Sensitivity 52/100 52%

Specificity 100/100 100%

Disease + −

+

Test

52

48

0

100

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point


Slide23 l.jpg

PPV 90/105 85.7%

NPV 85/95 89.5%

Sensitivity 90/100 90%

Specificity 85/100 85%

Disease + −

+

Test

90

10

15

85

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide24 l.jpg

PPV 95/117 81.2%

NPV 78/83 94%

Sensitivity 95/100 95%

Specificity 78/100 78%

Disease + −

+

Test

95

5

22

78

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


Slide25 l.jpg

PPV 100/135 74%

NPV 65/65 100%

Sensitivity 100/100 100%

Specificity 65/100 65%

Disease + −

+

Test

100

0

35

65

50%

Prevalence

Healthy population

Sick population

Healthyscores

Pathologicalscores

Cut-point

+


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