Table 6.
Sensitivity analysis. Univariate sensitivity analysis of base case scenario (based on 10 000 replications per line). All QALYs and costs are discounted at three percent per year (unless indicated otherwise). Line One gives results for the base case scenario; in each other line, one parameter is varied from the Base Case value (column 2) to a new value (column 3). All costs are given in $1 000 2004 U.S. dollars. Negative costs represent savings. Standard errors are given in parentheses. Note 1: new infections per year caused by a smear positive case. Note 2: rate per 100 000 person-years.
| Parameter varied | Value | Active cases | Add TB4s | Overall (all) | ||||
| Base | New | QALYs | Cost | QALYs | Cost | QALYs | Cost | |
| None | - | - | 4.1 (0.3) | -17 (1.6) | 2.9 (0.1) | -10 (0.7) | 7.7 (0.3) | -25 (1.5) |
| Passive treatment delay (days) | 74 | 100 | 5.8 (0.2) | -14 (1.4) | 3.7 (0.2) | -12 (1) | 10 (0.3) | -22 (1.7) |
| Screening delay (days) | 0 | 14 | 4.4 (0.3) | -17 (1.4) | 3.2 (0.2) | -11 (1.1) | 8.1 (0.2) | -25 (1.7) |
| Fraction of active cases | 3% | 6% | 8.1 (0.3) | -290 (2.2) | 3.1 (0.2) | -11 (0.7) | 12 (0.4) | -290 (2.5) |
| Baseline smear-positive rate | 7.5% | 15% | 5.2 (0.3) | -9.6 (0.9) | 3.3 (0.3) | -11 (0.8) | 9.3 (0.4) | -18 (0.9) |
| Transmission rate (Note 1) | 8 | 16 | 4.2 (0.3) | -22 (1.6) | 3.4 (0.2) | -12 (1) | 8.3 (0.3) | -33 (1.6) |
| Hospitalization rates | ||||||||
| Actively detect, smear pos. | 0.35 | 0.66 | 4.1 (0.2) | 0.8 (1) | 3.6 (0.2) | -11 (1) | 8.3 (0.3) | -7.2 (1.6) |
| Passively detect, smear pos. | 0.66 | 0.33 | 3.8 (0.13) | +8.3 (1.7) | 3.4 (0.2) | -1.0 (0.7) | +7.9 (0.3) | +12 (2.3) |
| Actively detect, smear neg. | 0.081 | 0.162 | 4.1 (0.2) | +27 (0.7) | 3 (0.18) | -8.6 (0.6) | 7.7 (0.3) | +22 (1.2) |
| Passively detect, smear neg. | 0.51 | 0.255 | 3.5 (0.3) | +140 (0.6) | 3.2 (0.15) | 1.5 (0.8) | 7.3 (0.3) | +150 (1) |
| Reactivation rates, Note 2 | ||||||||
| TB4s | 600 | 430 | 4 (0.3) | -16 (1.3) | 2.5 (0.15) | 1.0 (0.7) | 7.1 (0.3) | -12 (2) |
| Cost multipliers | ||||||||
| Hospitalization costs | same | +20% | 4.1 (0.3) | -67 (1.5) | 3 (0.13) | -16 (0.9) | 7.8 (0.3) | -83 (1.5) |
| Costs, excluding hospital | same | +20% | 3.4 (0.18) | +14 (0.9) | 3.5 (0.2) | -4.6 (1.1) | 7.7 (0.3) | +14 (1.6) |
| Selected costs | ||||||||
| Nurse refill visit | 16.80 | 8.40 | 3.7 (0.2) | -17 (1.1) | 3.3 (0.13) | -26 (0.8) | 7.5 (0.3) | -43 (1.4) |
| DOT visit | 19.23 | 25.00 | 4.5 (0.2) | -16 (1.2) | 3.0 (0.2) | -11 (1) | 7.8 (0.4) | -24 (1.8) |
| TST specificity | 0.99 | 0.875 | 4.1 (0.2) | -14 (1.1) | 3.0 (0.2) | -11 (0.9) | 7.6 (0.3) | -21 (1.2) |
| Fraction INH resistant | 0.13 | 0.2 | 3.9 (0.3) | -14 (1) | 2.3 (0.2) | -5.3 (0.8) | 6.7 (0.4) | -16 (0.9) |
| Risk multiplier, severe hepatitis | 1 | 3 | 3.9 (0.3) | -16 (0.9) | 3.0 (0.15) | -5.4 (0.5) | 7.6 (0.3) | -17 (1) |
| Selected disutilities | ||||||||
| Hepatitis hospitalization | 0.4 | 0.9 | 4.3 (0.3) | -15 (1.5) | 3.1 (0.2) | -10 (0.9) | 8.0 (0.3) | -23 (1.6) |
| Outpatient hepatitis | 0.265 | 0.5 | 4.3 (0.2) | -16 (1.3) | 3.1 (0.17) | -9.9 (1.1) | 8.0 (0.3) | -24 (2) |
| Other INH side-effects | 0.1 | 0.2 | 3.9 (0.2) | -15 (1) | 2.9 (0.13) | -10 (0.7) | 7.4 (0.2) | -22 (1.2) |
| Untreated TB | 0.1 | 0.2 | 4.8 (0.19) | -15 (1) | 3.6 (0.15) | -10 (0.9) | 9.0 (0.3) | -22 (1.5) |
| Lost QALYs, INH one month | 0 | 0.01 | 4.5 (0.3) | -15 (1.1) | -15 (0.2) | -9.9 (0.8) | -16 (0.4) | -22 (0.9) |
| Disutility multipliers | ||||||||
| TB hospitalization | 1 | 0.5 | 4.0 (0.19) | -16 (1.4) | 3.3 (0.1) | -10 (1) | 7.9 (0.2) | -24 (1.3) |
| Outpatient TB | 1 | 0.5 | 4.2 (0.3) | -16 (1.3) | 3.4 (0.2) | -8 (0.7) | 8.3 (0.3) | -21 (1.6) |
| Discount rate per year | 0.03 | 0.05 | 3.2 (0.15) | -13 (1) | 2.4 (0.13) | -6.9 (1.2) | 5.9 (0.2) | -16 (1.6) |
| TST sensitivity | 0.93 | 0.95 | 4.2 (0.2) | -17 (1.3) | 3.4 (0.15) | -11 (1) | 8.3 (0.3) | -25 (1.7) |
| TST specificity | 0.99 | 0.95 | ||||||