Thirty down, only ten to go?! Awareness and influence of a 10-year

time frame in TTO

Floor van Nooten, Xander Koolman, Werner Brouwer

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A paper introduced by Jan van Busschbach

LoLa, xx May 2010

Time Trade-Off

Wheelchair With a life expectancy: 50 years

How many years would you trade-off for a cure?

Max. trade-off: 10 years

QALY(wheel) = QALY(healthy) Y * V(wheel) = Y * V(healthy) 50 V(wheel) = 40 * 1.00

V(wheel) = 0.80

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Does the time frame matters?

1. Wheelchair, life expectancy: 50 years Max. trade-off: 10 years 50 V(wheel) = 40 * 1.00 V(wheel) = 0.80

2. Wheelchair, life expectancy: 10 years Max. trade-off: 2 years 10 V(wheel) = 8 * 1.00 V(wheel) = 0.80

3. Wheelchair, normal life expectancy: 50 years, but trade-off limited to 10 years

After 10 years you die anyway Irrespectively of real live expectancy

Research justification: Is option 3 the same as 1 and/or 2?

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Indeed time frames matters…

From earlier research1. Life time, long life expectancy: the lowest values

2. Life time, short life expectancy: higher values

3. Forced short life expectancy: even higher values

That is: If indeed subjects follow instructions….

Given that the instructions are complex… Especially with forced short life expectancy …

Research questions Forced short life is often used…. Do subjects adhere to forced short life expectancy

instructions?

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Different “emphasis” on instruction forced short life

RCT, using 10 years life year framing N = 656 Internet survey

Q1: Control condition No addition emphasis on 10 years life Debriefing afterwards: “What were you thinking?”

Q2: Experimental condition Added emphasis on forced short life

3 EQ-5D health state valuations with TT0 TTO1: 21211 TTO2: 22221 TTO3: 33312

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Results: table 2

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Questionnaire Q1 Q2 pN 339 317Percentage non-traders per TTOTTO1 78.2% 83.9% 0.073TTO2 71.1% 79.5% 0.01

5TTO3 23.0% 46.7% 0.00

0Years traded-offTTO1 0.443 (SD

1.223)0.401 (SD

1.293)0.085

TTO2 0.552 (SD 1.182)

0.546 (SD 1.455)

0.036

TTO3 2.083 (SD 2.362)

1.467 (SD 2.266)

0.000

Less subjects start trade off when explicit instruction about 10 year survival are given

Trade offs are higher when explicit instruction about 10 year survival are given

Additional results

Debriefing control condition Q1 43% did not think of forced short life…

Those who remembered instructions… TTO1: 21211….

• Lower values… not what might be expected TTO2: 22221….

• Higher values… but (univariate) not significant TTO3: 33312….

• Higher values… but (univariate) not significant

Multivariate ONLY TT02 & TTO 3… Significant results

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Additional results

Higher education: lower values Known already…

No age effect Known already…

Men trade off more: lower values New

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Conclusions

Subject forget instructions In the control condition, forced short life time is forgotten in 43% of

cases

Instructions matter Higher values with explicit instructions Those who forget, give lower values

Influence back ground variables Women (mothers) trade off less Higher education trade of more

Main conclusion: “These findings emphasize the importance of expected and

implied life expectancy in TTOs and raise important questions regarding the optimal design of TTO exercises.”

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Some problems…

Generalizability is over stretched 10 years life frame is rare Design is not a replication of that rare design

The relevance is over stretched Difference found are small Only in states with a low value

Back ground variables no part of research question No testing whether 10 years is a good thing Main conclusion should be:

• “These findings emphasize the importance of explicit instructions of implied life expectancy in TTOs with bad health states”

In stead of • “These findings emphasize the importance of expected and implied

life expectancy in TTOs and raise important questions regarding the optimal design of TTO exercises.”

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10 years life frame is rare

Forced short life is only used in some cases “Commonly, time trade-off (TTO) exercises use a 10-year time

horizon,…” “conventional TTO”

But this is only true for EQ-5D, MVH-protocol MVH-protocol is used a lot….

In EQ-5D and its translations

But others use different time frames SF-6D (SG) AQoL ? HUI ? 12D (VAS) Disease specific : IPSS, IIEF, …life time

Provide indications for which instruments it applies…

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Design is not a replication of the relevant earlier research

MVH-protocol differs from current design Is mentioned ones…

MVH is interview, not internet based There are explicit instruction in the interview about the 10

years

MVH used visual add The 10 life year span is visual

MVH allows for negative values

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Explicit instructions

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Visual add (prop)

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The design does not replicate

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Questionnaire Q1 Q2 pN 339 317UtilityTTO1 21211 (MVH value)

0.956 (0.814) 0.960 0.085

TTO2 22221 (MVH value)

0.945 (0.587) 0.945 0.036

TTO3 33312 (MVH value)

0.792 (-0.043) 0.853 0.000

“This point is emphasized by the fact that the utility scores obtained in our study are relatively high, when for instance compared to MVH_A1 scores…”

Are the differences relevant?

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Questionnaire Q1 Q2 pN 339 317UtilityTTO1 0.956 (SD

0.122)0.960 (SD

0.129)0.085

TTO2 0.945 (SD 0.118)

0.945 (SD 0.145)

0.036

TTO3 0.792 (SD 0.236)

0.853 (SD 0.227)

0.000

No statistical significance

No relevant difference

Could be relevant

TTO1 21211 (MVH value)

0.956 (0.814) 0.960 0.085

TTO2 22221 (MVH value)

0.945 (0.587) 0.945 0.036

TTO3 33312 (MVH value)

0.792 (-0.043) 0.853 0.000

Man trade more than women

The “mother hypothesis” “Such response modes might be related

to the position women have or envisage to have in life (e.g., as mothers). “

Neo-Darwinism Not the research question

Girls just wanna have fun… Cyndi Lauper (1983)

Paul Kind Cyndi is right… British Medical Journal 1998;316:736-

41.

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Fishing party…..

Debriefing control condition Q1 43% did not think of forced short life…

Those who remembered instructions… TTO1: 21211….

• Lower values… not what might be expected TTO2: 22221….

• Higher values… but (univariate) not significant TTO3: 33312….

• Higher values… but (univariate) not significant

Multivariate ONLY TT02 & TTO 3… Significant results…

Leave this out…..

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Conclusions

Subject forget instructions In the control condition, forced short life time is forgotten in

43% of cases

Instructions matter Higher values with explicit instructions

Main conclusion: “These findings emphasize the importance of explicit

instructions of implied life expectancy in TTOs with bad health states”

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