CADTH 2015 Symposium

1. Using a discrete choice
experiment with duration to
estimate values for health states
on the QALY scale
Nick Bansback
Assistant Professor
School of Population and Public Health, University of
British Columbia
CIHR New Investigator

2. The Problem (1)
• Generic preference based measures (e.g EQ-5D,
HUI, SF-6D) may sometimes not be sensitive enough
to capture important changes in health
Espallargues M et al. The impact of age-related macular degeneration on health status
utility values. Invest Ophthalmol Vis Sci. 2005 Nov;46(11):4016-23
McTaggart-Cowan et al. The validity of generic and condition-specific preference-based
instruments: the ability to discriminate asthma control status. Qual Life Res. 2008
Apr;17(3):453-62.

3. The Problem (1)
• Generic preference based measures (e.g EQ-5D,
HUI, SF-6D) may sometimes not be sensitive enough
to capture important changes in health
• As a result, there has been a huge increase in
conjoint/ Discrete Choice Experiment studies
looking at the value of more specific aspects of
health

4. The Problem (2)
• DCE/conjoint studies have not produced values on
the QALY scale. Hence none of these studies are
amenable to incorporating into economic
evaluation/informing policy

5. The Problem (2)
• DCE/conjoint studies have not produced values on
the QALY scale. Hence none of these studies are
amenable to incorporating into economic
evaluation/informing policy
• Conventional elicitation approaches (Time Trade
Off/Standard Gamble) are difficult to understand,
and so tend to need a face to face interview –
expensive and timely.

6. New Method: A discrete choice
experiment with a duration attribute
(referred to as DCEtto)
Health State A Health State B
Some problems in walking
about
No problems in walking about
No problems with self-care Some problems with self-care
Some problems with
performing my usual
activities
Some problems with performing
my usual activities
Moderate pain or discomfort No pain or discomfort
Not anxious or depressed Extremely anxious or depressed
Live for 10 years Live for 7 years
Choose A or B
Health State A Health State B
Some problems in walking
about
No problems in walking about
No problems with self-care No problems with self-care
Some problems with
performing my usual
activities
No problems with performing my
usual activities
Moderate pain or discomfort No pain or discomfort
Not anxious or depressed Not anxious or depressed
Live for 10 years Live for tyears
Vary t until indifferent between A and B
DCE Requires if health state A is preferred to B
and not the degree by which A is preferred to B
TTO DCEtto

7. Estimation
• Value for health state j in Time trade off:
• Estimate model on DCE data where x represents
vector or coefficients for each attribute level and t
is the duration
• Use estimated coefficients…
• To solve


8. Advantages to the DCEtto
• Simpler (fewer drop-outs)
• Enables incorporation of all respondents, increasing
power and representativeness
Cognition
• Included with no change in task or arbitrary
transformation
States worse
than dead
• DCEs rooted in economic theory (RUT)Theory
• Quick to complete
• Can be implemented on the web (cheaper)
Practical
Bansback, et al. "Using a discrete choice experiment to estimate health state utility values." Journal of health
economics 31.1 (2012): 306-318.
Bansback, et al. "Testing a discrete choice experiment including duration to value health states for large descriptive
systems: Addressing design and sampling issues." Social Science & Medicine 114 (2014): 38-48.

9. Case study
• New treatments for rheumatoid arthritis:
• Offer more convenient modes of administration
• But have less established evidence on long-term safety
vs

10. Example DCE choice set

11. Coeff t WTP
Infusion Ref
Injection 0.44* 10.39 2.11
Tablet 1.16* 25.66 5.57
Twice daily Ref
Once weekly 0.21* 4.87 0.99
Every 8 weeks 0.41* 9.85 1.97
40 people out of 100 benefit Ref
55 people out of 100 0.48* 12.47 2.31
70 people out of 100 1.20* 28.27 5.75
15 people out of 100 withdraw Ref
10 people out of 100 withdraw 0.22* 5.49 1.05
5 people out of 100 withdraw 0.27* 6.68 1.30
30 people out of 100 side-effect Ref
18 people out of 100 side-effect 0.30* 7.88 1.42
5 people out of 100 side-effect 0.62* 14.84 2.95
Limited confidence Ref
Moderate confidence 0.23* 5.88 1.12
Strong confidence 0.58* 14.37 2.76
Life years (linear) 0.21* 9.11
Number of responses 14980
Number of respondents 749
p2 0.214
Results (n=749)
• Market research
panel – inexpensive
• 3 weeks for data
collection
• Only 5 people
dropped out
• 80 people failed
consistency check,
but their
inclusion/exclusion
does not change
results
Harrison M, Marra C, Shojania K, Bansback N. Societal preferences for rheumatoid arthritis
treatments. Evidence from a Discrete Choice Experiment. Rheumatology. In Press

12. Results (on QALY scale)
Mode Frequency Benefit Serious SE Minor SE Imprecision
-.15
-.1
-.05
0
.05
.1
MRS(Utility)
InjectionvsInfusion
OralvsInfusion
WeeklyvsTwiceDaily
8-WeeklyvsTwiceDaily
55/100vs40/100
70/100vs40/100
10/100vs15/100
5/100vs15/100
18/100vs30/100
5/100vs30/100
ModeratevsHigh
LowvsHigh

13. Limitations
• Larger variance around results
• requires more responses than TTO studies
• In other DCEtto studies, questions remain about
large range of values
• Worst EQ-5D state ~-0.6
• Questions on how to incorporate into economic
evaluation
• Clearer for developing values for condition specific non
preference based QoL instruments (such as AQLQ)
• Possible double counting when combining with existing
generic instruments

14. Questions
• Is the DCEtto really easier than the TTO?
• Should we be using this approach to combine more
specific aspects of treatments with generic derived
QALYs?
• How can we validate the approach further?