Table 1.
Modeling assumptions for cost-effectiveness analysis.
Figure 1.
Flow diagram of the study selection process for inclusion in this paper's systematic review.
Overview of the review process for papers reporting on the efficacy of praziquantel repeat dosing for treatment of S. haematobium or S. mansoni infection in Africa. Shown are the reasons for exclusion/inclusion at each step of the systemic review.
Table 2.
Observed cure rates for schistosomiasis in selected field studies.
Table 3.
Observed reductions in Schistosoma infection intensity in selected field studies.
Figure 2.
Impact of single vs. repeated praziquantel dosing for cure of Schistosoma in high-risk African communities.
Upper panel shows efficacy of one- and two-dose regimens for treatment of S. mansoni according to the initial pre-treatment infection prevalence of study participants. Lower panel shows the relative efficacy of each treatment schedule for treatment of S. haematobium.
Figure 3.
Impact of single vs. repeated praziquantel dosing for intensity (egg output) reduction of Schistosoma infection.
Upper panel shows reported efficacy of one- and two-dose regimens for treatment of S.mansoni according to the initial pre-treatment infection prevalence of study participants. Lower panel shows the relative efficacy for each treatment schedule for treatment of S. haematobium.
Figure 4.
Schematic of the decision tree model used for cost-effectiveness analysis.
For each treatment strategy, individuals were cycled annually between three health states (uninfected, light, or heavy infection) or were lost to infection-related death or competing mortality. Transition was dependent on yearly participation with assigned treatment, or, if untreated, on the likelihood of spontaneous increase or reduction of infection without treatment. Input variables for the Markov model are listed in Tables S1 and S2. This is a simplified schematic of the full decision tree. Blue arrows indicate the places in the tree where ‘clones’ of the indicated sub-branches 1, 2, and 3 would be reproduced in the full tree diagram.
Figure 5.
Predicted infection intensity at different ages in a community having continuing Schistosoma transmission during control.
The upper panel indicates the life path experience with infection intensity (annual mean egg output per specimen) without therapy (No Rx), with single-dose annual therapy (1Rx), with or double-dose annual therapy (2 Rx), and 80% annual adherence in a community-based treatment program when there is continuing transmission of Schistosoma during the control intervention. The lower panel indicates the expected lifetime impact of the same regimens in a program treating school-age (5–15 yr) children only.
Table 4.
Incremental cost-effectiveness of a two dose regimen compared to a single dose regimen in a continuing community-wide mass drug campaign.
Table 5.
Incremental cost-effectiveness of a two dose regimen compared to a single dose regimen in a continuing school-age mass drug campaign.
Figure 6.
Sensitivity analysis of ICER estimates for egg output reduction in community-based therapy of S. haematobium.
Shown are the 11 most influential inputs to the Markov decision tree model and the effects of their variation on $US cost per cumulative egg-year averted when calculating the incremental cost effectiveness of single-dose vs. double-dose treatment regimens in community-based programs. The base case analysis from Table 4 is indicated by the vertical dotted line.
Figure 7.
Sensitivity analysis of ICER estimates for QALYs gained in community-based therapy of S. haematobium.
Shown are the 11 most influential inputs to the model and the effects of their variation on $US cost per lifetime QALY gained when calculating the incremental cost effectiveness of single-dose vs. double-dose treatment regimens in community-based programs. The base case analysis from Table 4 is indicated by the vertical dotted line.