Department of Health Management and Health Economics
Faculty of Medicine
University of Oslo
English
Written exam December 9th 2013, 0900-1300
HEVAL5130 – Modeling in economic evaluation II
Part one: Computer exercise, 3 hours
Results will be made available Thursday, January 2nd, see the board at the
Department of Health Management and Health Economics, Forskningsveien 3A.
The results will also be posted on Studentweb.
The receiving day of the results is the day the results are posted on the board at
the Department. Appeals must be submitted within three weeks of this date.
The Computer Exam consists of 4 pages including this one.
Remember to write down your candidate number so this is easily accessible
when the results become available.
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FINAL EXAM HEVAL 5130 – December 9, 2013 – 3 hours computer exercise
Below you will find information about the computer exercises. The necessary files are
uploaded onto the desktop of your computers. Please, save your Excel and Treeage files to
the memory stick provided when you have finished your assignment. Name your files with
candidate number, but NOT your own name. The memory sticks will be collected when the
computer session is finished.
You have at maximum 3 hours for the computer exercises. When you have finished your
computer exercises, you shall move away from the computers and answer theory questions.
Exercise 1 (Treeage computer exercise)
A. Add distributions to the TreeAge model provided (see table below or in Excel-file
provided)
B. Perform a Monte Carlo simulation and produce a scatter plot and a CEAC
C. Produce a graph that shows the EVPPI vs. WTP for the following groups of
parameters; probabilities, costs, utilities and efficacy.
D. Non-mandatory bonus exercise: Produce the TreeAge model in Excel
Values for model
Costs
Name
Description
cAmput
cBlind
Cost per year of being amputated (leg)
Cost per year for being blind
Cost per year of treatment for coronary heart
cCHD
disease
Yearly cost of control
Cost per year of treatment for cerebrovascular
cCVD
disease
cDiab
Cost per year of diabetes treatment
Yearly cost of intervention
Probabilities
Estimated
Low
cost
18252
7520
61668
13321
9544
7000
Description
pAmi
pAmput
pBlind
pStroke
QALYs
Probability of having AMI
Probability of amputation
Probability of becoming blind
Probability of having a stroke
Name
Description
qAmput
qBlind
qCHD
qCVD
qDiab
Effect
Yearly QALY when having amputated leg
Yearly QALY when being blind
Yearly QALY with CHD
Yearly qaly with cerebrovascular disease
Yearly QALY for diabetic
Name
Description
12537
Not uncertain
87532
4788
18000
2911
6665
Not uncertain
Estimated
QALY
0,6
0,58
0,69
0,67
0,75
Estimated
hazard ratio
2
28984
110015
165277
Estimated
probability
0,02
0,003
0,004
0,01
Name
6551
High
243022
Total
(N)
5678
789
1234
3456
Events per
year
114
2
5
35
Low
High
0,40
0,38
0,49
0,47
0,67
0,80
0,78
0,89
0,87
0,83
Low
High
rrIntAmi
rrIntAmput
rrIntBlind
rrIntDie
rrIntStr
Effect of intervention on AMI
Effect of intervention on risk of amputation
Effect of intervention on going blind
Effect of intervention on mortality
Effect of intervention on stroke
0,75
0,95
0,85
0,9
0,8
0,65
0,75
0,65
0,66
0,66
0,86
1,20
1,12
1,23
0,97
Exercise 2: Excel computer exercise - Cervical cancer diagnosis and treatment
A hypothetical group of women has underlying stage I cervical cancer. Each year their
cancer has a probability of being detected and cured. However, if their cancer was not
detected, there is a small stage-specific probability that the cancer will progress from Stage I
to II, from stage II to III and from III to IV. In addition, each year, the women with Stage IV
cancer face a probability of dying. Finally, there is a small probability of relapse back to
Stage I after a successful cure. A trial was conducted resulting in the following transition
table:
Transition table:
Stage 1 Stage 2 Stage 3 Stage 4
Stage 1
0
129
0
0
Stage 2
0
0
300
0
Stage 3
0
0
0
400
Stage 4
0
0
0
120
Cure
90
0
0
0
Total
Cured
631
900
600
240
300
Dead
0
0
0
240
0
760
1200
1000
600
390
The following are the annual costs and utilities associated with each health state:
Stage I Stage II
Stage III
Stage IV
Cured
$1,000
Cost, mean
$20,000 $25,500
$31,000
$35,000
$1,000
Cost, se
$10,000 $12,000
$15,000
$17,000
.98
Utility, mean
0.91
0.85
0.80
0.60
.05
Utility, se
.05
.05
.07
.04
There is a new drug (DrugX) that can be taken after the cancer has been cured. DrugX
reduces the transition probability from the Cured state back to Stage I by a relative risk (RR)
of 0.51. Assume a lognormal distribution (the ln(mean) and ln(se) have already been inserted
for you in the excel document (cells F40 and G40, respectively)). The cost of DrugX is
$2,350 per year (with no uncertainty).
An Excel document has been provided for you to perform a probabilistic sensitivity
analysis (PSA) in order to compare 1) the current standard of treatment (no drug) to 2) using
DrugX. Please become familiar with the different worksheets and notice that the equations to
calculate the Markov trace have been completed for you in the “Model” worksheet. Use a
Beta or Dirichlet distribution for the transition probabilities (where appropriate), Gamma
distribution for costs, Beta distribution for utilities and Lognormal for the relative risk.
1. Complete the model in Excel in order to be able to conduct a PSA. All blue/shaded
cells in the “Parameter” worksheet require user input (you need to fill in yourself)
while all cells that are white have been filled in for you and should NOT be changed.
Cells E9:E19 are highlighted in light green. For these cells you must decide if (and
which) cells require your input.
a. Use the logic function (=IF) to allow the model to switch back and forth
between deterministic (0) and probabilistic (1) (i.e., fill in the appropriate cells
in column B on the “Parameter” worksheet with a function that allows the user
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to toggle between using column C and column D by changing cell C3 between
1 and 0).
b. Fill in the alpha and beta values for the transition probabilities (cells F9:G19)
using the values from the transition table (located to the right on the
“Parameter” worksheet).
c. Fill in the mean and standard error (SE) for the costs and utilities using the
table provided above.
d. Calculate the deterministic value (column D) and fill in the correct equation to
pull a random draw from the appropriate distributions in the probabilistic
column (column C).
2. Which transition probability(ies) required a Dirichlet distribution? Briefly explain why.
Please fill in your answer in the text box provided for you on the “Answers” worksheet.
3. What are the alpha and beta parameters for the transition probability from Stage III
cancer to Stage IV cancer? Please fill in your answer in the text box provided for you
on the “Answers” worksheet.
4. Run the PSA macro provided for you on the “PSA_results” worksheet. This macro will
run 2,000 simulations. If you cannot complete the steps from question 1, you may still
receive partial credit for answering question 4 by using the provided simulation output
on the worksheet entitled, “USE ONLY IF NEEDED.”
Using the 2,000 simulations, calculate the probability DrugX is cost-effective for:
a. A willingness to pay threshold of $20,000 per QALY gained.
b. A willingness to pay threshold of $100,000 per QALY gained.
(Hint: If you calculate net monetary benefit, the function =COUNTIF(range; ”>0”) may
come in useful. The range should be referenced appropriately).Please show your
work in the appropriate worksheet and report your final answers in the text box
provided for you on the “Answers” worksheet.
When you have finished your computer exercises, you shall move away from the computers
and answer theory question. You have at maximum 3 hours for the computer exercises.
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