Transcript Role of uncertainty

Economic evaluation of health
programmes
Department of Epidemiology, Biostatistics
and Occupational Health
Class no. 23:
Nov 17, 2008
Plan of class
Difficulties with league tables and CE
thresholds
Role of uncertainty
Transferability to other settings
Role of the comparator in
league tables
 A2 compared to nothing has ICER of $9,100/QALY;
 Compared to A1 $5,000/QALY, but A1 compared to nothing
$50,000/QALY
 A1 is dominated through extended dominance and should never be
considered – A2 compared to A1 is misleading
Source:
Drummond et al.
2005, p. 329
Some difficulties with a costeffectiveness threshold
QALY may not capture all relevant
benefits
 Externalities, altruism
Transferability to different setting?
Size of program matters
 Think in terms of opportunity cost
Role of size of program
New (hypothetical!) antidepressant costs
$1,000 per year but has an ICER of only
$10,000/QALY
If 600k Quebeckers take it and it costs
$600 million, what is the opportunity cost
of $600 million?
Is it necessarily optimal to fund this?
NICE 2 guidelines
Don’t adopt
£30,000/QALY
May or may not adopt
£20,000/QALY
Adopt
Role of uncertainty (1)
 Modern cost-effectiveness analyses pay more attention
to uncertainty
 CEACs, Probabilistic sensitivity analysis
 Clinical decision-making: approve if new Tx more
effective (p<0.05)
 Arbitrary and can lead to excessively costly new interventions
being approved (role of insurance)
 Policy analysis: decision based on expected measure of
value, such as ICER
 Risk distributed on many people
Role of uncertainty (2)
 CEACs represent move away from decision rule based on fixed
error probabilities (such as 0.05 – which are also embedded in
confidence intervals).
Decision-maker can
decide whether to
base decision on
expected value (here,
£26,571 per QALY) or
consider probability
that ICER falls below
threshold
Source:
Drummond et al.
2005, p. 266
Issue of transferability
 Effectiveness of meds clearly transferable
 Effectiveness of surgical interventions may not be
 Differences in surgical skill?
 Clinical endpoints related to service system (e.g., %
unplanned surgical revascularization) may not transfer
well e.g., U.S. to Canada
 Economic data may not transfer well:
 Different available treatments (choice of comparator)
 Different practice patterns – may arise from differences in
incentives
 Different relative prices
Variability in cost-effectiveness
across countries
In Table below we see that drugs tend to appear to tend to be less costeffective in UK and Germany, than in France, Italy and Spain. But there are
many exceptions and the authors conclude that CE is one country cannot
be used to infer it in another
 Source: Barbieri,
Drummond et al. 05, p. 15
Other factors that can
influence cost-effectiveness
Demography and epidemiology of disease
 Ex: Prevention more cost-effective where
incidence is higher
How complex intervention implemented
Idiosyncratic factors for certain
interventions:
 Local unemployment rate for supported
employment
Adapting results from one
setting to another: 3 situations
1. Only clinical data from other country available

Use modelling to combine data from various sources
2. Clinical data + resource use/economic data from other
country available

Use modelling, may or may not use resource use data
3. Clinical data + economic data from several countries
available – need results for each country: several
options
May or may not pool clinical data – common to pool
May or may not pool resource use data, pricing separately by
country in each case


•
If no pooling, calculate separate ICER for each country
Example:Expected cost of 3 more
months of misoprostol prophylaxis
(Drummond et al. 92)
 To prevent gastric ulcers in patients on NSAIDs with
abdominal pain
 US trial (Graham et al. 88): Patients with OA, 400
micrograms daily for 3 months: 5.6% endoscopically
determined lesions vs 21.7% with placebo
 800 micrograms: 1.7%
 Fewer lesions: lower expected HC costs
 Evaluate CE in US but also UK, France and Belgium
Decision tree assumptions
 No misoprostol: ulcer rate as in placebo arm, less 40%
to account for silent ulcers
 Tx arm: non-compliers assigned trial placebo ulcer rate
 Diagnostic workup and ambulatory care patterns in each
country ascertained by local expert panels
 Hospital admission rates from epidemiological surveys
 Surgical rates and LOS from routine hospital statistics
 Free-standing surveys of costs in some countries
Source:
Drummond et al.
2005, p. 337
Results by country
Misoprostol more expensive in US yet more costeffective also: Why?