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Table 3 Sensitivity and specificity of the tuberculin skin test for diagnosing a tuberculosis infection

From: Skin thickness affects the result of tuberculin skin test in systemic sclerosis

Cut-off indurated reaction size by TST

 ≥ 5 mm

 ≥ 10 mm

 ≥ 15 mm

 ≥ 20 mm

Sensitivity

17.6%

5.9%

5.9%

5.9%

Specificity

87.4%

94.7%

97.4%

99.3%

ROC area

0.53

0.50

0.52

0.53

Positive likelihood ratio

1.40

1.11

2.22

8.88

Negative likelihood ratio

0.94

0.99

0.97

0.95

Positive predictive value

13.6%

11.1%

20.0%

50.0%

Negative predictive value

90.4%

89.9%

90.2%

90.4%

  1. TST tuberculin skin test, mm millimeters, ROC Receiver operating characteristic