Upload
audra-phillips
View
213
Download
0
Embed Size (px)
Citation preview
3/12/2009Decision and Cost-Effectiveness Analysis
James G. Kahnafter
Eran Bendavid
When Rationality Falters: Limitations and Extensions of
Decision Analysis
3/12/2009Decision and Cost-Effectiveness Analysis
Decision & cost-effectiveness analysis: Utilitarian & rational decision-making Everyone is equally deserving
Alternative (more realistic) assumptions: Behavioral economics Equity
Overview
Mental Accounting
3/12/2009Decision and Cost-Effectiveness Analysis
You set off to buy an iPod shuffle at what you believe to be the cheapest store in your neighborhood. When you arrive, you discover that the price of the Shuffle is $75, a price you believe is consistent with low estimates of the retail price.
A friend walks into the store and tells you a store 10 minutes away sells Shuffles for $55.
Do you go to the other store?Now suppose you are buying a MacBook Pro for
$1960, and a friend tells you it sells for $1940 in a store 10 minutes away. Do you go?
Normative Problem Formulation
3/12/2009Decision and Cost-Effectiveness Analysis
Classical decision theory axioms Ordering of preference Transitivity of preference Quantification of
judgment Comparison of
alternatives It’s the delta that matters
Cost benefit rationale
“Risky prospects arecharacterized by their possible outcomes and by the probabilities of these outcomes.
The same option, however, can be framed or described
in different ways.” -- Tversky & Kahneman, 1981
Framing Effects in Medical Decision-Making: Treatments
3/12/2009Decision and Cost-Effectiveness Analysis
When framed positively (i.e. survival vs. mortality): Respondents 1.5 x more likely to choose surgery
over other treatments (i.e. radiotherapy) Respondents demonstrated increased preference
for invasive/toxic treatments Same framing effect noted in hypothetical &
real life treatment decisionsIntervention use intention higher when
results presented as RRR vs. ARR or NNT
RRR, ARR, and NNT
3/12/2009Decision and Cost-Effectiveness Analysis
RRR = Relative Risk ReductionARR = Absolute Risk ReductionNNT = Numbers Needed to Treat Dead AliveMeds 404 921CABG 350 974
Risk of death (from having CABG) = 350/1324 = 0.264Relative risk of death = 0.264/0.305 = 0.87 = 87%RRR = Amt of risk of death is reduced by surgery: 100% - 87%
= 13% ARR = Absolute amt of risk surgery reduces death: 30.5% -
25.4% = 4.1% NNT = # pts needing surgery to prevent 1 death: 1/ARR = 24
Source: http://www.ebm.worcestervts.co.uk/trial_results.htm
Role of equity
3/12/2009Decision and Cost-Effectiveness Analysis
Efficiency and Equity Both important for health care resource allocation
decisions Few guidelines for measuring or incorporating
equity Equity ~ Values
How can equity concerns be incorporated in cost-effectiveness analyses?
What is equity?
3/12/2009Decision and Cost-Effectiveness Analysis
An equal and fair distributionAre treatments fairly allocated? Or
Are benefits fairly distributed? No guidance on how to assess
Vertical Equity
3/12/2009Decision and Cost-Effectiveness Analysis
Principle of vertical equity = allocation linked to “need”
Greater care is given to people with greater health needs
Sicker patients first priority for funding Goal is to create equity in eventual health status
Paying attention to equity: Could make some relatively inefficient technologies more
attractive If benefits groups with greater claim to treatment Or could make efficient options less attractive
3/12/2009Decision and Cost-Effectiveness Analysis
Vertical equity may be controversial -- if your definition of “need” is different than mine
Assume we accept vertical equityWhat characterizes equity?How should it measured?
Controversy
Are All QALYs Gains Equivalent?
3/12/2009Decision and Cost-Effectiveness Analysis
4 QALYs
0
5
10
15
20
25
0 0.2 0.4 0.6 0.8 1
Quality of Life
Life
Exp
ect
an
cy
B
A
CD
E
1 QALY
7 QALYs
A’
B ′
E ′
C ′D ′
Each associated with a gain of 3 QALYs!
Steps in Applying Equity to CEA
3/12/2009Decision and Cost-Effectiveness Analysis
1.Define groups which could receive priority to advance equity
2.Derive equity weights3.Determine how equity weights can be applied to
results of cost-effectiveness analyses (CEA) 4.Apply equity weighting to CEA results as a form of
sensitivity analysis
Some Possible Equity Factors
3/12/2009Decision and Cost-Effectiveness Analysis
Baseline life expectancy
Baseline quality of life
Improvement in or final life expectancy
Improvement in or final quality of life
Distribution of benefits (number of people)
Health care endowment (prior expenditure)
Age
Personal behaviours
Relation to others
Social status
Steps in Applying Equity to CEA
3/12/2009Decision and Cost-Effectiveness Analysis
1.Define groups which could receive priority to advance equity
2.Derive equity weights3.Determine how equity weights can be applied to
results of cost-effectiveness analyses (CEA) 4.Apply equity weighting to CEA results as a form of
sensitivity analysis
Survey to Understand Equity
3/5/2009MS&E 292 - Health Policy Modeling
Pilot in elected officials, municipal and provincial public clerks.
Participants recruited from waiting rooms at major Toronto downtown teaching hospital.
Asked to imagine they were voting in a referendum between 2 programs.
An Example
3/12/2009Decision and Cost-Effectiveness Analysis
AttributesScenario
A B
Baseline QOL 30 30
Gain in QOL 0 15
Baseline LE 10 10
Gain in LE 10 2
N 10,000 100
Prior Allocation 50,000 5,000
Age 75 15
Number Selecting (%) 79 (29) 191 (71)
Significant factors in equity…
3/12/2009Decision and Cost-Effectiveness Analysis
Consistent with prioritization for those with poorer health
Less prior resource allocation viewed as having priority
Equal priority two groups alike except: Had a quality of life that was 50 points worse Had received about $13,000 less in prior
resources
Some Factors Not Significant
3/12/2009Decision and Cost-Effectiveness Analysis
Number of people expected to benefit
Potential improvement in quality of life
Could have important implications for resource allocation models
Distributional aspects (“how many benefit?”) may be less important than the characteristics of individuals (“who benefits?”)
Steps in Applying Equity to CEA
3/12/2009Decision and Cost-Effectiveness Analysis
1.Define groups which could receive priority to advance equity
2.Derive equity weights3.Determine how equity weights can be applied to
results of cost-effectiveness analyses (CEA) 4.Apply equity weighting to CEA results as a form of
sensitivity analysis
Equity-Weighted QALYs: eQALYs
3/12/2009Decision and Cost-Effectiveness Analysis
Vertical equity Implies society values some health gains
more than othersFor example
A QALY gain a sick person more valuable than a QALY gain for a well person
Cancer drug vs. lifestyle drugThus increase or decrease QALYsQALYs transformed into “eQALYs”
= equity-weighted QALYs
Limitations of eQALYs
3/12/2009Decision and Cost-Effectiveness Analysis
QALYs already controversialConstruct is artificial, somewhat foreignMeasurement issuesAlready conflate survival, quality of lifePutting equity in might confuse more than it
illuminatesAnd exacerbate concerns about subjectivity, valuesi.e. eQALY components:
Survival Objective Quality of life (preference) Subjective Equity weight Subjective and
value-laden
Steps in Applying Equity to CEA
3/12/2009Decision and Cost-Effectiveness Analysis
1.Define groups which should receive priority to advance equity
2.Derive equity weights3.Determine how equity weights can be applied to
results of cost-effectiveness analyses (CEA) 4.Apply equity weighting to CEA results as a form of
sensitivity analysis