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Table 3 Analysis of effectiveness of each screening strategy

From: Different screening strategies (single or dual) for the diagnosis of suspected latent tuberculosis: a cost effectiveness analysis

Effectiveness Measures

TST

T-SPOT.TB

QFT-GIT

TST/T-SPOT.TB

TST/QFT-GIT

Numbers of post-primary TB cases in 2 year period

4.52

3.80

4.03

4.67

4.85

Number of TB cases prevented by screening strategy

2.98

3.70

3.47

2.83

2.65

Numbers of people treated for LTBI

284

228

242

174

168

Numbers of true positives treated

184

228

214

174

163

Numbers of false positives treated

101

0

28

0

5

Numbers of people treated for LTBI per case of active TB prevented (NNT)

95.5

61.7

69.7

61.7

63.6

  1. Effectiveness measures relate to outcomes and costs for entire cohort of 1,000 contacts over the 2 year examination period. No screening results in 7.5 cases of post-primary TB in the 2 year period. (TST - Tuberculin Skin Test, QFT-GIT - Quantiferon-TB Gold-In-Tube, NNT- number needed to treat)