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Table 3 Model projections with Xpert as the diagnostic tool for each triage option when no X-ray available for triage (Fig. 1a). (Base Case – Microscopy diagnostic tool and no triage)

From: Modelling the impact of chest X-ray and alternative triage approaches prior to seeking a tuberculosis diagnosis

Diagnostic & triage options

Presumptive TB cases receiving diagnostic test per yr.

True TB cases b starting treatment per year and case detection % c

False TB cases d starting TB treatment per year

Time between starting triage and receiving diagnosis (days)

Additional true TB cases starting treatment over base case per year a

Additional cost compared to base case per year a (US$ 000 s)

Cost per additional true TB patient diagnosed and treated n(US$) a

Microscopy No Triage (base case)

10,281

1238      75%

543

6.0

0

0

0

Xpert No Triage

10,284

1375      83%

419

5.0

137 (57, 217)

581 (555, 607)

4242 (1372, 7111)

Xpert T2 Cough 1wk

8411

1197      72%

340

4.0

−41 (−118, 36)

233 (223, 244)

No benefit over base

Xpert T3 Cough>3wks

5183

878      53%

193

2.4

−360 (− 439, −281)

− 393 (− 410, − 375)

No benefit over base

Xpert T4 Clinical score

5470

1148      70%

191

2.5

−90 (−166, −14)

−51 (−53, −49)

No benefit over base

Xpert T5 ANN

7469

1369      82%

285

3.5

131 (39, 223)

367 (351, 384)

2805 (907, 4703)

Xpert T6 TPP optimal

3290

1320      80%

75

1.5

82 (2, 162)

−49 (−52, −47)

− 604 (−1012, − 195)

Xpert T7 TPP minimal

4046

1245      76%

121

1.8

7 (−74, 88)

−54 (−56, −52)

Minimal benefit over base case

  1. aNumbers in brackets represent 95% confidence limits
  2. bTrue TB cases include both bacteriologically confirmed and clinically diagnosed cases that have TB
  3. cCase detection rate calculated as the number of true TB cases identified through the complete triage and diagnostic algorithm, divided by the number of TB cases in the presumptive-TB case population calculated from the assumed TB prevalence (Table 2)
  4. dFalse TB cases are individuals diagnosed with TB and placed on TB treatment, but do not have TB (false positives)