Table A.10.
Results of univariate sensitivity analysis: cost per TB case prevented and cost per QALY gained by 3HP (compared to 9H) when varying one parameter value at a time*
| Parameter | Health system perspective
|
Societal perspective
|
||
|---|---|---|---|---|
| Incremental cost per TB case prevented US$ | Incremental cost per QALY gained US$ | Incremental cost per TB case prevented US$ | Incremental cost per QALY gained US$ | |
| Base case scenario | 21525 | 4565 | 4294 | 911 |
| Directly observed therapy cost/dose ($17.76) | ||||
| $0 | <0 | <0 | <0 | <0 |
| $35 | 56124 | 11902 | 38893 | 8248 |
| 3HP medication cost per dose ($12.31) | ||||
| $5 | 6 854 | 1 454 | <0 | <0 |
| $25 | 46992 | 9965 | 29762 | 6311 |
| $35 | 67061 | 14221 | 39796 | 8439 |
| TB hospitalization probability (49%) | ||||
| 0% | 32855 | 6983 | 17188 | 3653 |
| 75% | 15140 | 3207 | <0 | <0 |
| Proportional change in risk of progression to TB disease (100%) | ||||
| 50% | 47861 | 7163 | 19007 | 2845 |
| 150% | 8 002 | 2 001 | <0 | <0 |
| 200% | 1 941 | 594 | <0 | <0 |
| Patient hourly time value ($12.73) | ||||
| $0 | 21525 | 4565 | 18669 | 3959 |
| $7.50 | 21525 | 4565 | 10200 | 2163 |
| $17.00 | 21525 | 4565 | <0 | <0 |
| Secondary TB cases per primary case (0.46) | ||||
| 0 | 34895 | 6436 | 12153 | 2242 |
| 0.6 | 18753 | 4104 | 2665 | 583 |
| 9H completion proportion (68%) | ||||
| 63% | 14906 | 3248 | 1145 | 250 |
| 57% | 15170 | 3464 | 2648 | 605 |
| 51% | 11378 | 3183 | 1043 | 292 |
| 3HP completion proportion (83%) | ||||
| 76% | 16969 | 3209 | <0 | <0 |
| 69% | 19259 | 3922 | <0 | <0 |
| 62% | 15220 | 2518 | <0 | <0 |
| 3HP toxicity probability (8.2%) | ||||
| 3% | 16629 | 3749 | <0 | <0 |
| 13% | 25458 | 5158 | 7686 | 1557 |
| Probability of death from TB disease (5.8%) | ||||
| 2% | 21332 | 5655 | 3828 | 1015 |
| 15% | 21424 | 3856 | 3862 | 695 |
| Cost of hospitalization for TB ($25 495) | ||||
| $10000 | 28411 | 6025 | 11181 | 2371 |
| $40000 | 15078 | 3197 | <0 | <0 |
| Annual QALY loss from LTBI treatment (0.03) | ||||
| 0 | 21525 | 9132 | 4294 | 1822 |
| 0.06 | 21525 | 3043 | 4294 | 607 |
| Annual QALY loss from previous TB (0.05) | ||||
| 0 | 21525 | 5961 | 4294 | 1189 |
| 0.10 | 21525 | 3698 | 4294 | 738 |
| Annual QALY loss from drug toxicity (0.25) | ||||
| 0 | 21525 | 4520 | 4294 | 902 |
| 0.50 | 21525 | 4610 | 4294 | 920 |
| Annual QALY loss from hospitalization (0.50) | ||||
| 0 | 21525 | 4571 | 4294 | 912 |
| 1.00 | 21525 | 4558 | 4294 | 909 |
| Annual QALY loss from anti-tuberculosis treatment (0.10) | ||||
| 0 | 21525 | 4613 | 4294 | 920 |
| 0.20 | 21525 | 4517 | 4294 | 901 |
| Discount rate (3%) | ||||
| 0% | 15 825 | 2 573 | 959 | 156 |
| 5% | 24766 | 5732 | 6184 | 1431 |
| Simulation duration (20 years) | ||||
| 5 years | 29468 | 5717 | 8914 | 1729 |
| 10 years | 25052 | 5078 | 6342 | 1286 |
| 50 years | 17321 | 3931 | 1633 | 371 |
| Cost of initial clinic visit ($166)† | ||||
| $125 | 21525 | 4565 | 4294 | 911 |
| $205 | 21525 | 4565 | 4294 | 911 |
| Cost of follow-up clinic visit ($28) | ||||
| $20 | 28559 | 6056 | 11328 | 2402 |
| $35 | 15237 | 3231 | <0 | <0 |
Base case values are reported in parentheses. Shaded entries (where the incremental cost-effectiveness ratios are negative) represent scenarios where 3HP is cost-saving compared to 9H. Simulation run for each set of parameter values with 100 000 simulated individuals for each regimen. Costs are in 2010 US dollars.
As the same cost of the initial clinic visit is incurred for all individuals regardless of regimen, it has no bearing on the relative cost-effectiveness of the two regimens.
TB = tuberculosis; QALY = quality-adjusted life years; 3HP = 12-dose regimen of weekly rifapentine plus isoniazid; 9H = 9 months of daily, self-administered isoniazid; LTBI = latent tuberculous infection.