Required to conduct PSA using the decision-tree from the Patel case study (i.e. the rotavirus vaccination case study). Please follow the instructions below to modify your model, conduct PSA and answer the questions.
Step 1. Modify the tree model
Run the model and note your base case results. Based on a Tornado Diagram from the model, we have selected important variables for PSA. (You do not need to run the Tornado analysis). Please convert these variables to distributions. The distribution type and input parameters are reported in Table 1 below.Calculate the likeliest values. (Hint: μ = [(a + b + c)/3]
Step 2. Calculate the ICER again
After completing the new tree, report your base-case ICER in Table 2- hint: set Preference as Cost-Effectiveness, then Analysis >> Cost-Effectiveness.
Step 3. Conduct PSA and report the results. Use: 10,000 iterations with baseline: current practice & comparator: national program
a. Create an ICE scatterplot (turn in).
b. Explain your scatterplot.Which quadrant do most of your iterations fall into?What does this mean?
c. Plot the ICER distribution graph (turn in).
d. Report the ICER distribution statistics in the Table 3 below.
e. Explain your graph.
f. Plot the acceptability curves with a willingness to pay of $20,000 (turn in).
g. If the WTP in Pakistan is 6000 $/death averted, what is the probability that the national program will be cost-effective? What if the WTP is 10000 $/death averted?
h. Explain the figure in general terms.
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Table 1. Variables and distributions for the PSA
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Variable Name
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Description
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Baseline
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Distribution
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Min
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Max
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likeliest
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Epidemiology inputs
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pRVInfected
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RVGE cumulative incidence for 5 years
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0.663
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Triangular
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0.5
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0.9
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pDieOfRVGE
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RVGE case-fatality ratio
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0.006
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Triangular
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0.001
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0.01
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pEfficacy
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Vaccine Efficacy
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0.483
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Triangular
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0.223
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0.661
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pCurVaccineCoverage
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Current rotavirus vaccine coverage
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0.06
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Triangular
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0.01
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0.1
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pExpVaccineCoverage
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Expected vaccine coverage (national programs)
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0.85
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Triangular
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0.65
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1
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pHomeCare
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Patients get home care
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0.888
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Triangular
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0.7
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1
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pFormalOutpatient
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Among those with formal care, the proportion of getting outpatient care
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0.6875
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Triangular
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0.5
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0.9
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Cost Inputs
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cUnitVaccine
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Unit cost for the vaccine
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5
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Triangular
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1
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7.5
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cHospitalization
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Hospitalization cost (4-day stay)
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33.4
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Triangular
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25.05
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41.75
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Table 2. PSA Results
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Strategy
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Cost
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Incr Cost
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Effectiveness
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IncrEff
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ICER
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Current practice
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National Program
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Are the results the same from the model prior to your entering the distributions?
Table 3: PSA ICER results
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Mean
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SD
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Median
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95% Confidence Intervals
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2.5%
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97.5%
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ICER
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