Transcript Monday, Oct. 8: Modeling in CE analysis

Monday, Oct. 8:
Modeling in CE analysis
by
Donald S. Shepard, Ph.D.
Schneider Institute for Health Policy
Heller School, MS 035
Brandeis University
Waltham, MA 02454-9110 USA
Tel: 781-736-3975 • Fax: 781-736-3965
Web: http://www.sihp.brandeis.edu/shepard
E-mail: [email protected]
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Practical information
• Teaching assistant:
[email protected]
• Administrative assistant:
Linda Purrini, Next to library in Heller
781-736-3930
[email protected]
• Cost of packet: $6.00
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Cost-effectiveness of alternative
peri-natal AZT regimens
3000
2500
Cost ($)
2000
breast+short_short
1500
breast+long_short
breast+long_long
breast+short_long
1000
formula+no treat
formula+long_short
formula+long_long
formula+short_long
500
formula+short_short
None
Efficient
0
-
10
20
30
40
DALYs gained
3
50
60
70
Cost-Effectiveness of Sildenafil, 1
Abstract
Background: Coverage of sildenafil by health
insurance plans is a contentious issue.
Objective: To evaluate the cost-effectiveness of
sildenafil treatment for erectile dysfunction.
Design: A Markov decision model to estimate the
incremental cost-effectiveness of sildenafil compared
with no drug therapy.
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Cost-Effectiveness of Sildenafil, 2
Data Sources: Values for the efficacy and safety of
sildenafil and quality-of-life utilities were obtained
from the published medical literature. Base-case
values were chosen to bias against sildenafil use.
Target Population: Men 60 years of age with erectile
dysfunction.
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Cost-Effectiveness of Sildenafil, 3
Time Horizon: Lifetime.
Perspective: Societal and third-party payer.
Intervention: Sildenafil or no treatment in identical
hypothetical cohorts.
Outcome Measures: Cost per quality-adjusted lifeyear (QALY) gained.
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Markov model for erectile
dysfunction
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8
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Cost-Effectiveness of Sildenafil, 4
Results of Base-Case Analysis:
The cost per QALY gained for sildenafil treatment
compared with no therapy was $11 290 from the
societal perspective and $11 230 from the third-party
payer perspective.
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Sildenafil, sensitivity analysis
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Cost-Effectiveness of Sildenafil, 5
Results of Sensitivity Analysis:
From the societal perspective, the cost per QALY
gained associated with sildenafil was less than
$50,000 if treatment-related morbidity was less
than 0.8% per year, mortality was less than 0.55%
per year, treatment was successful in more than
40.2% of patients, or sildenafil cost less than $244
per month. The results were sensitive to variation
of erectile dysfunction utilities, but cost per QALY
gained was less than $50,000 if successful
treatment increased utility values by 0.05 or more
on a scale of 0 (death) to 1 (perfect health).
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Cost-Effectiveness of Sildenafil, 6
Conclusions:
In an analysis biased against use of sildenafil, the
cost-effectiveness of sildenafil treatment compared
favorably with that of accepted therapies for other
medical conditions.
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Cost-Effectiveness of Dengue
Control
Source:
Shepard, D.S. and Halstead, S.B. Dengue
(with notes on yellow fever and Japanese
encephalitis). In: Disease Control Priorities for
Developing Countries, Jamison, D.T., Mosley,
W.H., and Measham, A.R., eds. Bobadilla J.L.,
New York: Oxford University Press for the
World Bank, pp. 303-320, 1993.
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Model for dengue case management
Dengue infections with no
interventions (CASES)
SHOCK.R
No serious illness
Dengue Hemorrhagic Fever
Dengue Shock Syndrome
DHF/DSS
FATAL
Would die without improved
case management
SALVAGE
Recover
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Die despite improved
case management
Model for dengue vaccine
Healthy, no infection (STAND.POP)
COVERAGE
No vaccination
Receive vaccination
VACC.EF
Dengue
infection
No dengue
infection
Dengue
infection
CASES
Dengue infection (CASES)
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No dengue
infection
Dengue model variables:
Morbidity and mortality
STAND.POP: The number of persons in the standard population (an
arbitrary size) to which the model is applied. Here STAND.POP is one
million persons of all ages.
CASES: Number of dengue infections without vaccination or vector
control in the hypothetical birth cohort (all births within the standard
population in one year).
SHOCK.R (Shock rate): Proportion of dengue infections that progress to
dengue shock syndrome.
FATAL: Case-fatality rate of DDS 1960-65.
CLINICAL: Proportion of dengue infections which are clinically
apparent.
DUR: Average duration of clinical illness, expressed in disability-adjusted
life years.
COHORT: Number of persons in one year's birth cohort in the standard
17 population.
Dengue model variables:
Effectiveness
YEAR.D: Discounted remaining life expectancy of a person at the
average age of death of a fatal dengue case.
SALVAGE: Proportional reduction in case fatality rate of DHF/DSS after
improved case management.
SHORTEN: Proportional reduction in duration of illness among
hospitalized cases after improved case management.
VACC.EF (vaccine efficacy): Proportional reduction in number of cases.
COVERAGE: Proportion of birth cohort vaccinated.
VCTRC.EF: (vector chemical efficacy): Proportional reduction in number
of cases from chemical vector control.
VCTRE.EF: (vector environmental efficacy): Proportional reduction in
number of cases from environmental vector control.
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Dengue model:
Model for single interventions
At the baseline (policy BASE):
D.BASELINE = CASES  SHOCK.R  FATAL.
With case management improved (policy C):
DEATHS = CASES  SHOCK.R  FATAL • (1 -SALVAGE).
With immunization or vaccination (policy I):
DEATHS = CASES (1 - VACC.EF  COVERAGE)  SHOCK.R 
FATAL.
For each strategy, the number of deaths averted is
D.AVERTED = D.BASELINE - DEATHS.
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Dengue model:
Two-way combinations of
interventions
With vaccination and case management (policy IC):
DEATHS = CASES • ( 1 - VACC.EF • COVERAGE)
• SHOCK.R • (1 - SALVAGE) •FATAL.
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Table 2. Efficacy and Costs of Interventions for Dengue (per 1 million pop.)
Deaths
Intervention
Baseline (BASE)
Case management improved (C)
Environmental vector control (E)
Environmental control and
casemanagement (EC)
Immunization (I)
Immunization and case management (IC)
Immunization, case management,and
environmental control (ICE)
Immunization, case management, and
vector chemically controlled (IM
Immunization and environmental vector
control (IE)
Immunization and vector chemically
controlled IV)
Vector chemically controlled (v)
Vector chemically controlled and case
management (vC)
Source: Authors' cost-effectiveness model.
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DALYs saved from
averted Mortality Morbidity
0
0
21.74
554
3
22.52
574
118
Total
0
557
692
Percent
0
92
95
Net Average Average
cost
cost
cost
per per death
($)
$000 DALY($)
0
0
0
327
587
15,042
2,172
3,139
96,461
23.61
16.44
23.10
602
419
589
118
86
87
720
505
676
100
69
97
2,189
727
828
3,040
1,440
1,224
92,712
44,251
35,827
23.68
604
123
727
100
2,959
4,071
124,968
23.28
594
98
692
98
1,250
1,806
53,691
23.34
595
122
717
98
2,954
4,117
126,537
18.62
7.11
475
181
97
37
572
219
79
30
1,180
435
2,062
1,992
63,372
61,234
22.33
569
39
609
94
664
1,091
29,754
Table 3. Incremental Cost-Effectiveness
of Interventions for Dengue Control
Intervention
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DALYs
Net
cost
saved
($000)
Average cost per
per DALY
($)
death
($)
No vaccine and health system not developed
Baseline (BASE)
0
0
0
0
Vector chemically controlled (V)
219
435
1,992
61,234
Environmental vector control (E)
692
2,172
3,139
96,461
No vaccine but developed health system
Baseline
0
0
0
0
Case management improved (C )
557
327
587
15,042
Vector chemically controlled and
case management (C)
609
664
1,091
29,754
Environmental control and case
management (EC)
720
2,189
3,040
92,712
With vaccine but health system not developed
Baseline (BASE)
0
0
0
0
Immunization (1)
505
727
1,440
44,251
Immunization and vector
chemically controlled (IV)
572
1,180
2,062
63,372
Environmental vector control (E)
692
2,172
3,139
96,461
Immunization and environmental control (IE)
717
2,954
4,117 126,537
With vaccine and developed health system
Baseline (BASE)
0
0
0
0
Case management improved (C )
557
327
587
15,042
Immunization and case
management (IC)
676
828
1,224
35,827
Immunization, case management,
and vector chemically
controlled (ICV)
692
1,250
1,806
53,691
Environmental control and case
management (EC)
720
2,189
3,040
92,712
Immunization, case management,
and environmental control (ICE)
727
2,959
4,071 124,968
Note: Only policies that are feasible and economically efficient are listed.
Source: Authors' cost-effectiveness model.
Additional
Additional
cost
Incremental
cost
DALYs
gained
($000)
Per DALY ($)
0
219
474
0
435
1,737
0
1,992
3,668
0
557
0
327
0
587
51
337
6,568
111
1,524
13,696
0
505
0
727
0
1,440
67
120
452
992
6,754
8,278
25
781
30,927
0
557
0
327
0
587
119
501
4,217
16
422
26,363
28
939
33,643
7
770
112,933
Legend to Dengue CE graphs
Efficient policies
• Inefficient policies
Note: BASE = Baseline; Efficient policies : C = Improved
case management, VC = Vector chemically controlled
and case management, IC = Vaccination and case
management; IVC = Vaccination, case management, and
vector chemically controlled, EC = Environmental vector
control and case management, ICE = Vaccination, case
management, and environmental vector control; Inefficient
policies: V = Vector chemically controlled, I =
Immunization, IV = Immunization and vector chemically
controlled, E = Environmental vector control, IE =
Immunization and environmental control.
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Figure 4. DALYs saved with vaccine
in developed health system
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Fig 5. Deaths averted with vaccine in
developed health system
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Final Assignment of CE module, 1
Purpose: See how cost-effectiveness analysis can be applied to a subject of interest to
you.
Background: Select and cite an article or report of interest to you that describes the
effectiveness or cost-effectiveness of a clinical intervention or program in a human
services sector. For suggestions or help in identifying articles, see the instructor or
teaching assistant. For example, the instructor’s report, “Economic analysis of anti-viral
therapy in Botswana” provides data on the cost-effectiveness of AZT for pregnant
women. A copy is available on the web site under “downloads.” Two types of papers are
possible.
Alternative A: Perform a preliminary cost-effectiveness analysis. If the study is an
effectiveness study only, perform a preliminary cost-effectiveness analysis. Clearly
indicate the alternatives you wish to compare and the effectiveness measure, and provide
illustrative results. Use existing data where readily available, and explicitly assume values
for other the unknown data. Interpret the findings. Discuss what kinds of data would be
needed to convert the preliminary study into a more valid cost-effectiveness study, and
where would they be obtained? Which items do you think are most critical?
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Final Assignment of CE module, 2
Alternative B: Discuss a cost-effectiveness analysis. If the study is a costeffectivenessstudy, discuss the appropriateness of the data, analysis, and interpretation,
and put the results in a larger context. For example, compare the intervention under study
with other interventions for the same disease or the same population.
Submission: The length of the paper should be about 6 double spaced pages, including
any tables or figures per student. Two or more students may work together and submit a
joint paper that is proportionally more extensive, and longer if desired (6 pages per
student). Please submit to Linda Purrini, administrative assistant, Heller G6, tel: 781-7363930, [email protected]. Also, please include a copy a summary, abstract, or full
copy of the article with your submission. The paper may also be submitted electronically
to Ms. Purrini.
Schedule: Due Thursday, Oct. 25, 2001 (10 days after the last class).
Evaluation: The module will be graded according to each student’s registration (audit,
pass-fail, or letter grade) based on this final exercise, other exercises, and class
participation. In addition, the instructors plan to give written comments on this exercise.
The instructors look forward to your papers.
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Final class session
Monday, Oct. 15, 6 pm – 9 pm
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Final class, Oct. 15
• Help us identify illustrative, empirical, preferably
intervention studies outside of the health sector
• Collect and read the selected studies (distributed later this
week)
• Be prepared to discuss the cost-effectiveness framework:
• What are the alternative(s)?
• What are the costs?
• What are the outcomes (effectiveness)?
• How do we interpret cost-effectiveness results?
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