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Table 1 Diagnostic performance of the scent detection dogs

From: Scent dog identification of SARS-CoV-2 infections in different body fluids

Session

Dog

Detection

SARS-CoV-2 infection status

Total number of sample presentations

Diagnostic specificity

(Sp)

Diagnostic sensitivity

(Se)

Confidence interval (95% CI) Sp

Confidence interval (95% CI) Se

Positive predictive value (PPV)

Negative predictive value (NPV)

Confidence interval (95% CI) PPV

Confidence interval (95% CI) NPV

Accuracy

Fisher’s exact test

positive

negative

Non-inactivated saliva samples (after 1 week of training with inactivated saliva samples)

Dog 1

Yes

15

5

132

0.9537

0.625

0.89618–0.98007

0.4271–0.78841

0.75

0.91964

0.5313–0.88814

0.8543–0.95715

0.89394

< 0.0001

No

9

103

Dog 2

Yes

14

5

95

0.9375

0.93333

0.8619–0.97301

0.70183–0.99658

0.73684

0.98684

0.51208–0.88194

0.92916–0.99933

0.93684

< 0.0001

No

1

75

Dog 3

Yes

16

5

136

0.95614

0.72727

0.90142–0.98112

0.51848–0.86849

0.7619

0.94783

0.54909–0.89372

0.89083–0.97587

0.91912

< 0.0001

No

6

109

Dog 4

Yes

9

12

79

0.8209

0.75

0.71253–0.89446

0.46769–0.91106

0.42857

0.94828

0.2447–0.63453

0.85861–0.9859

0.81013

0.0002

No

3

55

Dog 5

Yes

16

3

81

0.95161

0.84211

0.86712–0.98681

0.62435–0.9448

0.84211

0.95161

0.62435–0.9448

0.86712–0.98681

0.92593

< 0.0001

No

3

59

Dog 6

Yes

16

5

107

0.94318

0.84211

0.8738–0.97549

0.62435–0.9448

0.7619

0.96512

0.54909–0.89372

0.90239–0.99049

0.92523

< 0.0001

No

3

83

Dog 7

Yes

20

0

114

1

0.83333

0.95906–1

0.64147–0.93321

1

0.95745

0.83887–1

0.89564–0.98333

0.96491

< 0.0001

No

4

90

Dog 8

Yes

17

3

92

0.96

1

0.88887–0.9891

0.81568–1

0.85

1

0.63958–0.94763

0.94935–1

0.96739

< 0.0001

No

0

72

Dog 9

Yes

17

4

102

0.95238

0.94444

0.88387–0.98133

0.74243–0.99715

0.80952

0.98765

0.59999–0.92332

0.93333–0.99937

0.95098

< 0.0001

No

1

80

Dog 10

Yes

14

7

129

0.93396

0.6087

0.86992–0.96765

0.40786–0.77842

0.66667

0.91667

0.45373–0.82805

0.84917–0.95554

0.87597

< 0.0001

No

9

99

      

Median Sp

Median Se

95% CI of median

Sp

95% CI of median

Se

Median PPV

Median NPV

95% CI of median

PPV

95% CI of median NPV

Median

accuracy

95% CI of median accuracy

      

0.952

0.83772

0.93396–0.96

0.625–0.94444

0.7619

0.95453

0.66667–0.85

0.91964–0.98765

0.92558

0.87597–0.96491

Non-inactivated sweat samples

Dog 1

Yes

10

0

67

1

0.55556

0.9273–1

0.33716–0.7544

1

0.85965

0.72247–1

0.74676–0.92713

0.8806

< 0.0001

No

8

49

Dog 2

Yes

10

4

57

0.91489

1

0.80068–0.96641

0.72247–1

0.71429

1

0.45351–0.88279

0.91799–1

0.92982

< 0.0001

No

0

43

Dog 3

Yes

10

5

69

0.90909

0.71429

0.80423–0.96054

0.45351–0.88279

0.66667

0.92593

0.41714–0.84824

0.82446–0.97082

0.86957

< 0.0001

No

4

50

Dog 4

Yes

10

3

62

0.94231

1

0.84357–0.98428

0.72247–1

0.76923

1

0.49744–0.9182

0.9273–1

0.95161

< 0.0001

No

0

49

Dog 5

Yes

10

7

71

0.87719

0.71429

0.76754–0.93922

0.45351–0.88279

0.58824

0.92593

0.36005–0.78389

0.82446–0.97082

0.84507

< 0.0001

No

4

50

Dog 6

Yes

10

4

65

0.92157

0.71429

0.815–0.96908

0.45351–0.88279

0.71429

0.92157

0.45351–0.88279

0.815–0.96908

0.87692

< 0.0001

No

4

47

Dog 7

Yes

10

1

44

0.9697

0.90909

0.84681–0.99845

0.62264–0.99534

0.90909

0.9697

0.62264–0.99534

0.84681–0.99845

0.95455

< 0.0001

No

1

32

Dog 8

Yes

10

1

56

0.97778

0.90909

0.88433–0.99886

0.62264–0.99534

0.90909

0.97778

0.62264–0.99534

0.88433–0.99886

0.96429

< 0.0001

No

1

44

Dog 9

Yes

10

1

40

0.96552

0.90909

0.82824–0.99823

0.62264–0.99534

0.90909

0.96552

0.62264–0.99534

0.82824–0.99823

0.95

< 0.0001

No

1

28

      

Median Sp

Median Se

95% CI of median

Sp

95% CI of median

Se

Median PPV

Median NPV

95% CI of median

PPV

95% CI of median NPV

Median

accuracy

95% CI of median accuracy

      

0.94231

0.90909

0.90909–0.97778

0.71429–1

0.76923

0.96552

0.66667–0.90909

0.92157–1

0.92982

0.86957–0.95455

Non-inactivated urine samples

Dog 1

Yes

10

1

91

0.98592

0.5

0.92444–0.99928

0.2993–0.7007

0.90909

0.875

0.62264–0.99534

0.78497–0.93066

0.87912

< 0.0001

No

10

70

Dog 2

Yes

10

2

50

0.94872

0.90909

0.83114–0.99089

0.62264–0.99534

0.83333

0.97368

0.55197–0.97039

0.86505–0.99865

0.94

< 0.0001

No

1

37

Dog 3

Yes

10

1

63

0.98

0.76923

0.89505–0.99897

0.49744–0.9182

0.90909

0.94231

0.62264–0.99534

0.84357–0.98428

0.93651

< 0.0001

No

3

49

Dog 4

Yes

8

1

72

0.98333

0.66667

0.91145–0.99915

0.39062–0.86188

0.88889

0.93651

0.565–0.9943

0.84781–0.97503

0.93056

< 0.0001

No

4

59

Dog 5

Yes

10

2

49

0.94872

1

0.83114–0.99089

0.72247–1

0.83333

1

0.55197–0.97039

0.90594–1

0.95918

< 0.0001

No

0

37

Dog 6

Yes

10

2

66

0.96429

1

0.87881–0.99365

0.72247–1

0.83333

1

0.55197–0.97039

0.93359–1

0.9697

< 0.0001

No

0

54

Dog 7

Yes

10

0

41

1

0.90909

0.88649–1

0.62264–0.99534

1

0.96774

0.72247–1

0.83806–0.99835

0.97561

< 0.0001

No

1

30

Dog 8

Yes

10

0

47

1

1

0.90594–1

0.72247–1

1

1

0.72247–1

0.90594–1

1

< 0.0001

No

0

37

Dog 9

Yes

10

0

49

1

1

0.91033–1

0.72247–1

1

1

0.72247–1

0.91033–1

1

< 0.0001

No

0

39

Dog 10

Yes

10

4

66

0.92857

1

0.83025–0.97187

0.72247–1

0.71429

1

0.45351–0.88279

0.93121–1

0.93939

< 0.0001

No

0

52

      

Median Sp

Median Se

95% CI of median

Sp

95% CI of median

Se

Median PPV

Median NPV

95% CI of median

PPV

95% CI of median NPV

Median

accuracy

95% CI of median accuracy

      

0.98167

0.95455

0.94872–1

0.66667–1

0.89899

0.98684

0.83333–1

0.93651–1

0.94959

0.93056–1

Non-inactivated saliva samples

Dog 1

Yes

19

1

147

0.992

0.86364

0.95608–0.99959

0.66665–0.95251

0.95

0.97638

0.76387–0.99744

0.93285–0.99356

0.97279

< 0.0001

No

3

124

Dog 2

Yes

20

5

128

0.95098

0.76923

0.89034–0.97888

0.57948–0.88966

0.8

0.94175

0.60869–0.91139

0.8787–0.97303

0.91406

< 0.0001

No

6

97

Dog 3

Yes

20

7

173

0.95205

0.74074

0.90435–0.97658

0.55321–0.86830

0.74074

0.95205

0.55321–0.8683

0.90435–0.97658

0.91908

< 0.0001

No

7

139

Dog 4

Yes

20

4

137

0.96522

0.90909

0.91397–0.98639

0.72185–0.98385

0.83333

0.9823

0.64147–0.93321

0.93776–0.99686

0.9562

< 0.0001

No

2

111

Dog 5

Yes

20

5

120

0.94949

0.95238

0.88717–0.97824

0.77331–0.99756

0.8

0.98947

0.60869–0.91139

0.94276–0.99946

0.95

< 0.0001

No

1

94

Dog 6

Yes

20

4

111

0.95506

0.90909

0.89007–0.98239

0.72185–0.98385

0.83333

0.97701

0.64147–0.93321

0.92001–0.99592

0.94595

< 0.0001

No

2

85

Dog 7

Yes

18

8

163

0.94074

0.64286

0.88742–0.96967

0.45830–0.79294

0.69231

0.92701

0.50012–0.83499

0.87085–0.95987

0.88957

< 0.0001

No

10

127

Dog 8

Yes

20

6

164

0.95556

0.68966

0.90643–0.97947

0.50770–0.82724

0.76923

0.93478

0.57948–0.88966

0.8807–0.96531

0.90854

< 0.0001

No

9

129

Dog 9

Yes

20

1

112

0.98901

0.95238

0.94035–0.99944

0.77331–0.99756

0.95238

0.98901

0.77331–0.99756

0.94035–0.99944

0.98214

< 0.0001

No

1

90

Dog 10

Yes

19

5

191

0.96875

0.6129

0.92894–0.98658

0.43824–0.76267

0.79167

0.92814

0.5953–0.90755

0.87861–0.95842

0.91099

< 0.0001

No

12

155

      

Median Sp

Median Se

95% CI of median

Sp

95% CI of median

Se

Median PPV

Median NPV

95% CI of median

PPV

95% CI of median NPV

Median

accuracy

95% CI of median accuracy

      

0.95531

0.81644

0.94949–0.98901

0.64286–0.95238

0.8

0.96422

0.74074–0.9

0.92814–0.98901

0.93252

0.90854–0.97279

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BMC Infectious Diseases

ISSN: 1471-2334

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