Table 1.
Parameter Estimates
| Parameter | Base Case | Sensitivity range | References |
|---|---|---|---|
| TB Dynamics | |||
| Prevalence of TB Disease | 0.14a | 0.1-0.5 | (18) |
| MDR Prevalence among all TB in Uganda | 0.01 | 0.006-0.022 | (2) |
| Sensitivity in Children Under Five | |||
| Sensitivity of Current Clinical Practice for TB | 0.68 | 0.3-0.9 | (13) |
| Sensitivity of MODS for TB | 0.47 | 0.3-0.9 | (20) |
| Sensitivity of Xpert MTB/RIF (Xpert) for TB | 0.44 | 0.09-0.9 | (20) |
| Sensitivity of MODS for resistance to rifampin | 0.83 | 0.749-1.0 | (31) |
| Sensitivity of Xpert for resistance to rifampin | 0.83 | 0.66666-1.0 | (31) |
| Specificity for TB | |||
| Specificity of Current Clinical Diagnosis for TB | 0.80 | 0.22-0.93 | (13) |
| Specificity of MODS for TB | 0.97b | 0.86 - 0.997 | (20) |
| Specificity of Xpert for TB | 0.97b | 0.86 - 0.997 | (20) |
| Specificity of MODS for resistance to rifampin | 0.99 | 0.819-1.0 | (31) |
| Specificity of Xpert for resistance to rifampin | 0.99 | 0.819-1.0 | (31) |
| Treatment | |||
| Probability of not completing treatment | 0.14 | 0.112-0.168 | (14) |
| Probability of death due to MODS treatment delayc | 0.06 | 0.01-0.10 | (19) |
| Treatment Outcome | |||
| Probability of Death in Patients with Untreated TBd | 0.35a | 0.15-1.0 | (19) |
| Probability of Death in Patients Without TBe | 0.10 | 0.01-0.34 | (15) |
| Probability of Death in patients appropriately treated for MDR TB | 0.18 | 0.144-0.216 | (16) |
| Probability of Death in patients appropriately treated for non-MDR TB | 0.13 | 0.113-0.138 | (17) |
| Probability of Death in patients appropriately treated for DS TB after delay in diagnosing | 0.18 | 0.160-0.195 | (17, 19) |
| Probability of Death in patients appropriately treated for MDR TB after delay in diagnosing | 0.23 | 0.206 - 0.252 | (17, 19) |
| Outcome measure | |||
| Life Expectancy after TB cure (years) | 50 | 37-54 | (22) |
| Unit Cost Estimates | |||
|---|---|---|---|
| Variable costs | Costs ($) | Sensitivity Range | Reference |
| Specimen collection - Gastric Aspirate | 8.99 | 8.09-9.90 | (26) |
| Current Clinical Practice - cost including X-ray and potential microscopy f | 14.00 | 12.60-15.40 | Current costs USD - Mulago Hospital, Uganda |
| MODS f | 20.00 | 8.80-22.0 | Current costs USD - Mulago Hospital, Uganda |
| Xpert f | 30.00 | 30.00-82.00 | Current costs USD - Mulago Hospital, Uganda |
| Total Cost of treating a single case of drug-sensitive TB | 193.66 | 152.83-234.49 | (5) |
| Total Cost of treating a single case of RTF resistant TB | 1841.36 | 1345.17-2337.56 | (5) |
Given wide uncertainty about this parameter, multiple values were tested in the primary analysis as per figures 3 and 4. Values shown here were used to generate results in table 2.
Given no evidence of differential specificity between MODS and Xpert, we used the same value in this analysis.
This probability was calculated to account for patients who get diagnosed too late due to diagnostic delay
The probability of death in untreated TB is assumed to be the same for patients with MDR TB if not treated appropriately.
This probability was conservatively assumed to be equal whether TB treatment was initiated or not.
The unit costs are estimated from lab charges in the National TB referral lab in Kampala, Uganda. They are assumed to be representative of market costs, including labor. Therefore, they are all-inclusive from the healthcare perspective.