Table 1.
List of Model Parameters by Country
| Parameter | Value (Range) | Source(s) | ||||
|---|---|---|---|---|---|---|
| India | Philippines | South Africa | Uganda | Vietnam | ||
| TB prevalence (based on Xpert-Ultra positive TB) per 100 000 screening participants | 872 (800, 944)a | 3199 (2,804, 3591)a | 2352 (1,874, 2832)a | 1107 (806, 1405)a | 889 (718, 1101)a | [23–27] |
| Sensitivity of Xpert Ultra | 100% (100%, 100%)b | [28] | ||||
| Specificity of Xpert Ultra | 98.8% (97.2%, 99.5%) | [5] | ||||
| Sensitivity of Hypothetical Screening test |
95.0% (93.4%, 96.0%)b,c | [13] | ||||
| Specificity of Hypothetical Screening test |
70.0% (63.6%, 74.5%)b,c | [13] | ||||
| Sensitivity of CRP | 64.6% (49.5%, 77.8%)b | STOMP-TBd | ||||
| Specificity of CRP | 84.2% (77.4%, 89.6%)b | STOMP-TBd | ||||
| Proportion of screen positive people unable to sufficiently produce sputum | 12.8% (0%, 26.3%) | [17] | ||||
| Pre-treatment loss to follow-up | 13.0% (0%, 22.1%) | 9.3% (0%, 18.7%) | 9.5% (0%, 20.0%) | 9.5% (0%, 19.6%) | 9.3% (0%, 18.7%) | [14–16, 18–20] |
| Cost of Hypothetical Screening test cartridge | $2.00 (fixed) | [13] | ||||
| Cost of Hypothetical Screening test, total | $10.92 (8.69, 13.15)e | $16.96 (13.22, 20.70)e,f | $26.87 (24.58, 29.15)e | $15.49 (12.49, 21.52)e | $16.96 (13.22, 20.70)e | [8–11] |
| Cost of CRP test assay | $3.50 (fixed) | Boditechg | ||||
| Cost of CRP test, total | $4.50 (4.00, 5.00) | Assumption | ||||
| Cost of Xpert Ultra cartridge | $9.98 (fixed) | [29] | ||||
| Cost of Xpert Ultra, total | $18.90 (16.67, 21.13) | $24.94 (21.20, 28.68)f | $34.85 (32.56, 37.13) | $23.47 (20.47, 29.50) | $24.94 (21.10, 28.68) | [8–11] |
| Cost of treatment for TB, per person | $327 (245, 409) | $392 (294, 490) | $999 (749, 1249) | $418 (314, 523) | $441 (331, 552) | [30] |
| WTP threshold (USD) | $560 (146, 974) | $1061 (324, 1798) | $3725 (1,486, 5963) | $192 (14, 371) | $712 (182, 1242) | [21] |
| DALYs averted per case detected | 1.92 (1.44, 2.40)h | [31, 32] | ||||
Abbreviations: CRP, C-reactive protein; DALY, disability adjusted life year; R2D2, Rapid Research in Diagnostics Development TB Network; TB, tuberculosis; USD, United States dollars; WTP, willingness to pay.
aAssuming 4 times the national prevalence Xpert Ultra confirmed TB among adults (>15 years old).
bSensitivity and specificity relative to Xpert Ultra positive samples.
cUsing the minimal requirement of triage test target product profile (TPP), and assuming a range of ± 25%.
dUnpublished data from a community-based screening context.
eAssuming equivalent non-cartridge costs as Xpert Ultra.
fNo cost values specific for the Philippines were available; therefore, costs equal to those in Vietnam were assumed.
gPersonal communication with a Boditech representative.
hAssuming a range of the number of DALYs averted per case detected of ± 25%.