Table 1. Input parameters of selected variables.
| Variable | Baseline value | Sensitivity analysis range | Reference |
|---|---|---|---|
| Probability | |||
| Maternal HTLV-1 seropositivity rate | 0.0027 | 0.001–0.004 | 8 |
| HTLV-1 transmission rate with long-term breastfeeding (≧6 months) from HTLV-1 seropositive mothers to children | 0.203 | 0.1–0.3 | 7 |
| HTLV-1 transmission rate with short-term breastfeeding (<6 months) from HTLV-1 seropositive mothers to children | 0.074 | 0.02–0.1 | 7 |
| HTLV-1 transmission rate with bottle feeding from HTLV-1 seropositive mothers to children | 0.025 | 0.001–0.06 | 7 |
| Proportion of long-term breastfeeding* (≧6 months) | 0.374 | 0.3–0.5 | 28,29 |
| Proportion of short-term breastfeeding* (<6 months) | 0.591 | 0.5–0.7 | 28,29 |
| Proportion of bottle feeding | 0.035 | 0–0.1 | 28,29 |
| Annual ATL rate in HTLV-1 carriers | 0.000976 | 0.0005–0.0015 | 23 |
| Proportion of acute-type ATL in ATL patients | 0.508 | 0.477–0.539 | 1 |
| Proportion of lymphoma-type ATL in ATL patients | 0.249 | 0.222–0.276 | 1 |
| Proportion of unfavorable chronic-type ATL in ATL patients | 0.094 | 0.076–0.112 | 1 |
| Proportion of favorable chronic-type ATL in ATL patients | 0.044 | 0.031–0.057 | 1 |
| Proportion of smoldering-type ATL in ATL patients | 0.105 | 0.086–0.124 | 1 |
| Transformation rate from favorable chronic-type ATL to acute-type ATL | 0.446 | 0.4–0.8 | 26,27 |
| Transformation rate from smoldering-type ATL to acute-type ATL | 0.6 | 0.4–0.8 | 26,27 |
| HAM/TSP rate in HTLV-1 carriers | 0.000033 | 0.000022–0.000044 | 24 |
| Transformation rate from HAM/TSP to ATL | 0.00381 | 0.00343–0.00419 | 3 |
| 4-year acute-type ATL survival rate (%) | 16.8 | 6.7–26.9 | 1 |
| 4-year lymphoma-type ATL survival rate (%) | 19.6 | 9.7–29.5 | 1 |
| 4-year unfavorable chronic-type ATL survival rate (%) | 26.6 | 16.8–36.0 | 1 |
| Mortality of favorable chronic-type and smoldering-type ATL | 0.079 | 0.06–0.12 | 26,27 |
| Mortality of HAM/TSP | 0.024 | 0.015–0.033 | 4 |
| Adjusted risk of death due to any cause in people with HTLV-1 when compared with HTLV-1-negative counterparts | 1.57 | 1.37–1.80 | 30 |
| Cost, US$ (US$1 = ¥ 96.76) | |||
| HTLV-1 antibody initial and confirmation test | 76.4 | 57.3–95.5 | 32,34 |
| Treatment for ATL | 108,581 | 81,436–135,725 | 2,25,32 |
| Treatment for HAM/TSP | 6,700 | 5,025–8,375 | 24,32 |
| Utility | |||
| HTLV-1 uninfected state | 1 | 0.7–1 | 37,38,39 |
| HTLV-1 carrier | 0.712 | 0.684–1 | |
| Acute-type ATL | 0.67 | 0.58–0.76 | |
| Lymphoma-type ATL | 0.67 | 0.58–0.76 | |
| Unfavorable chronic-type ATL | 0.67 | 0.58–0.76 | |
| Favorable chronic-type ATL | 0.69 | 0.60–0.78 | |
| Smoldering-type ATL | 0.7 | 0.61–0.79 | |
| HAM/TSP | 0.299 | 0.271–0.327 | |
| Death | 0 | N/A | |
HTLV-1, human T cell leukemia virus 1; ATL, Adult T-cell leukemia-lymphoma; HAM/TSP, HTLV-1-associated myelopathy-tropical spastic paraparesis; N/A, not applicable
* Breastfeeding includes a mixture of breastfeeding and bottle feeding.