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Table 4 Model projections with Xpert as the diagnostic tool for each triage option with X-ray available for triage (Fig. 1b). (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 (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 9204 1370      83% 401 4.4 132 (54, 210) 536 (512, 559) 4057 (1313, 6802)
Xpert T3 Cough>3wks 7340 1290      80% 289 3.5 52 (−15, 119) 278 (266, 290) 5345 (1729, 8960)
Xpert T4 Clinical score 7365 1353      82% 296 3.5 114 (38, 190) 380 (363, 397) 3331 (1078, 5584)
Xpert T5 ANN 8477 1352      82% 341 4.0 114 (43, 187) 451 (431, 470) 3952 (1278, 6625)
Xpert T6 TPP optimal 5823 1354      82% 218 2.8 116 (45, 187) 172 (164, 179) 1481 (479, 2483)
Xpert T7 TPP minimal 6367 1366      83% 231 3.1 128 (56, 200) 301 (287, 314) 2349 (760, 3938)
  1. aNumbers in brackets represent 95% confidence limits
  2. bTB cases include both bacteriologically confirmed and clinically diagnosed cases that have TB
  3. cCase detection rate was 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)