Table 1.
Input parameters of selected variables.
Fig 1.
Simplified schematic depiction of a state transition diagram.
The health states in the model are shown to be oval. In a yearly model cycle, transition paths occur between the health states and other health states, as represented by the arrows. HTLV-1, human T-cell leukemia virus type 1; ATL, adult T-cell leukemia-lymphoma; HAM/TSP, HTLV-1-associated myelopathy-tropical spastic paraparesis.
Table 2.
Base-case analysis.
Fig 2.
ICER tornado diagram for HTLV-1 antenatal screening versus no screening.
HTLV-1 antenatal screening is cost-effective compared with no screening at a WTP threshold of US$50,000 per QALY gained when the maternal HTLV-1 seropositivity rate is greater than 0.0022, HTLV-1 transmission rate with long-term breastfeeding from HTLV-1 seropositive mothers to children is greater than 0.154, HTLV-1 transmission rate with short-term breastfeeding from HTLV-1 seropositive mothers to children is greater than 0.043, HTLV-1 transmission rate with bottle feeding from HTLV-1 seropositive mothers to children is lower than 0.044, the health utility value of HTLV-1 carriers is lower than 0.77, and the cost of HTLV-1 antibody test is lower than US$94.8. ICER, incremental cost-effectiveness ratio; WTP, willingness-to-pay; QALY, quality-adjusted life-year; HTLV-1, human T cell leukemia virus 1; ATL, adult T-cell leukemia-lymphoma; HAM/TSP, HTLV-1-associated myelopathy-tropical spastic paraparesis.
Fig 3.
Two-way sensitivity analysis for the maternal HTLV-1 seropositivity rate and the proportion of long-term breastfeeding.
HTLV-1 antenatal screening is optimal in the blue region which includes the base-case result (x). No screening is optimal in the orchid region. This figure shows that HTLV-1 antenatal screening is more cost-effective the higher the maternal HTLV-1 seropositivity rate and the higher the proportion of long-term breastfeeding. WTP, willingness-to-pay; HTLV-1, human T cell leukemia virus 1.
Fig 4.
Cost-effectiveness acceptability curve.
The probabilistic sensitivity analysis analyzes 1000 simulations of the model in which input parameters are randomly varied across pre-specified statistical distributions. The x-axis represents the WTP threshold. The acceptability curve showed that HTLV-1 antenatal screening is 81.1% cost-effective at a WTP threshold of US$50,000 per QALY gained. CE, cost-effectiveness; QALY, quality-adjusted life-year; WTP, willingness-to-pay; HTLV-1, human T cell leukemia virus 1.
Fig 5.
ICE scatterplot with a 95% confidence ellipse at a WTP threshold of US$50,000 per QALY gained.
Each dot represents a single simulation for a total of 1000 simulations. The ICE scatterplot showed that HTLV-1 antenatal screening is dominant in 811 trials to no screening in 1000 trials. ICE, incremental cost-effectiveness; QALY, quality-adjusted life-year; WTP, willingness-to-pay; HTLV-1, human T cell leukemia virus 1.
Table 3.
Economic and health outcomes of HTLV-1 antenatal screening vs no screening.