A consistency test of the time trade-off

Bleichrodt, Han; Pinto, José Luı̀s; Abellán-Perpiñán, José-María

doi:10.1016/s0167-6296(03)00046-8

Cited by 48 publications

(26 citation statements)

References 32 publications

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“…Instead, we used a choice task to better approximate the choice-based nature of economic practice. Our results suggest that loss aversion for short durations is far less important for choice tasks than matching tasks, in accordance with other studies [9, 23]. In particular, the shortest durations ( n β = 1,3,7) did not yield higher TTO scores than the other durations, suggesting that a choice based design causes subjects to put less emphasis on the maximization of remaining lifetime.…”

Section: Discussionsupporting

confidence: 91%

“…The use of round numbers might encourage subjects to respond in round numbers as well, causing a proportional heuristic [10]. We chose these somewhat odd durations to make this heuristic less salient [9]. Contrary to most previous studies, we used short, intermediate, and long gauge durations, enabling a more complete test of CPTO.…”

Section: Methodsmentioning

confidence: 99%

“…The descriptive deficiencies of the QALY model cause the TTO method to be susceptible to several distorting influences, threatening its suitability to measure individuals’ true preferences for health. Examples of factors leading to distortions include administration mode [6], discounting [7], loss aversion [8, 9], maximum endurable time (MET) [10, 11], and scale compatibility [12]. A result of these (and possibly other) factors in TTO is the empirical falsification of constant proportional trade-offs (CPTO, [13, 14]).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Constantly Proving The Opposite? A test of CPTO using a broad time horizon and correcting for discounting

Attema

Brouwer

2011

Qual Life Res

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PurposeAn important assumption underlying the quality-adjusted life year (QALY) model is that people trade off life years against health in the same proportion irrespective of the number of remaining life years. This is known as the constant proportional trade-offs (CPTO) condition. Previous studies have produced mixed empirical evidence about the validity of CPTO. This paper is the first to test CPTO using the time trade-off (TTO) method for a broad time horizon.MethodsIn a sample of 83 students, we use a choice based TTO protocol to elicit TTO scores for back pain, using ten different gauge durations ranging between 1 and 46 years. The TTO scores are corrected for discounting, which is elicited by means of the direct method.ResultsWe find average TTO scores varying between 0.72 and 0.81. Although the scores do not differ much for different durations in absolute terms, some differences are significant, rejecting CPTO, with and without correcting for discounting. No clear relationship between TTO scores and gauge duration is found. An anchoring and rounding heuristic to some extent explains our results.ConclusionsOur findings highlight the importance of elicitation methods and context dependencies in QALY measurement and warrant detailed investigation of their influence.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constantly Proving The Opposite? A test of CPTO using a broad time horizon and correcting for discounting

Attema

Brouwer

2011

Qual Life Res

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“…This may again have been caused by MET. Bleichrodt et al [9] used five different durations that were not multiples of 5, so that they were not very susceptible to a proportional heuristic. These durations were of an intermediate and long-term nature.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Some empirical studies found support [4–6], while others rejected it [7, 8], or found mixed results [9]. Given the importance of the assumption and the mixed evidence for it, more research in this area seems warranted.…”

Section: Introductionmentioning

confidence: 99%

On the (not so) constant proportional trade-off in TTO

Attema

Brouwer

2010

Qual Life Res

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PurposeThe linear and power QALY models require that people in Time Trade-off (TTO) exercises sacrifice the same proportion of lifetime to obtain a health improvement, irrespective of the absolute amount. However, evidence on these constant proportional trade-offs (CPTOs) is mixed, indicating that these versions of the QALY model do not represent preferences. Still, it may be the case that a more general version of the QALY model represents preferences. This version has the property that people want to sacrifice the same proportion of utilities of lifetime for a health improvement, irrespective of the amount of this lifetime.MethodsWe use a new method to correct TTO scores for utility of life duration and test whether decision makers trade off utility of duration and quality at the same rate irrespective of duration.ResultsWe find a robust violation of CPTO for both uncorrected and corrected TTO scores. Remarkably, we find higher values for longer durations, contrary to most previous studies. This represents the only study correcting for utility of life duration to find such a violation.ConclusionsIt seems that the trade-off of life years is indeed not so constantly proportional and, therefore, that health state valuations depend on durations.

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A prospective cohort study defining utilities using time trade‐offs and the Euroqol‐5D to assess the impact of cancer‐related lymphedema

Cheville

Almoza

Courmier

et al. 2010

Cancer

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BACKGROUND The devastating impact of lymphedema on cancer survivors’ quality of life has prompted consideration of several changes in medical and surgical care. Unfortunately, our understanding of the benefits gained from these approaches relative to their cost remains limited. This study was designed to estimate utilities for lymphedema and characterize how utilities differ between subgroups defined by lymphedema etiology and distribution. METHODS A consecutive sample of 236 subjects with lymphedema seen at a lymphedema clinic completed both a time trade-off (TTO) exercise and the Euroqol 5D. Responses were adjusted in multivariate regression models for demographic factors, comorbidities, and lymphedema severity/location. RESULTS Most participants (167 of 236, 71%) had lymphedema as a consequence of cancer treatment; 123 with breast cancer and upper extremity involvement. Mean TTO utility estimates were consistently higher than Euroqol 5D estimates. Unadjusted TTO (0.85; standard deviation [SD], 0.21) and Euroqol 5D (0.76; SD, 0.18) scores diminished with increasing lymphedema stage and patient body mass index (BMI). Adjusted utility scores were lowest in patients with cancer-related lower extremity lymphedema (TTO=0.82; SD, 0.04 and Euroqol 5D=0.80; SD, 0.03). Breast cancer patients also had lower adjusted Euroqol 5D scores (0.80; SD, 0.02). CONCLUSIONS Lymphedema-associated utilities are in the range of 0.80. Lower utilities are observed for patients with higher lymphedema stages, elevated BMI, and cancer-related lymphedema. Greater expenditures for the prevention and treatment of cancer-related lymphedema are warranted.

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A consistency test of the time trade-off

Cited by 48 publications

References 32 publications

Constantly Proving The Opposite? A test of CPTO using a broad time horizon and correcting for discounting

Constantly Proving The Opposite? A test of CPTO using a broad time horizon and correcting for discounting

On the (not so) constant proportional trade-off in TTO

A prospective cohort study defining utilities using time trade‐offs and the Euroqol‐5D to assess the impact of cancer‐related lymphedema

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