Time Trade-off Values Research Articles

An exploration of methods for obtaining 0\u2009=\u2009dead anchors for latent scale EQ-5D-Y values

ObjectivesDiscrete choice experiments (DCEs) can be used to obtain latent scale values for the EQ-5D-Y, but these require anchoring at 0 = dead to meet the conventions of quality-adjusted life year (QALY) estimation. The primary aim of this study is to compare four preference elicitation methods for obtaining anchors for latent scale EQ-5D-Y values.MethodsFour methods were tested: visual analogue scale (VAS), DCE (with a duration attribute), lag-time time trade-off (TTO) and the location-of-dead (LOD) approach. In computer-assisted personal interviews, UK general public respondents valued EQ-5D-3L health states from an adult perspective and EQ-5D-Y health states from a 10-year-old child perspective. Respondents completed valuation tasks using all four methods, under both perspectives.Results349 interviews were conducted. Overall, respondents gave lower values under the adult perspective compared to the child perspective, with some variation across methods. The mean TTO value for the worst health state (33333) was about equal to dead in the child perspective and worse than dead in the adult perspective. The mean VAS rescaled value for 33333 was also higher in the child perspective. The DCE produced positive child perspective values and negative adult perspective values, though the models were not consistent. The LOD median rescaled value for 33333 was negative under both perspectives and higher in the child perspective.DiscussionThere was broad agreement across methods. Potential criteria for selecting a preferred anchoring method are presented. We conclude by discussing the decision-making circumstances under which utilities and QALY estimates for children and adults need to be commensurate to achieve allocative efficiency.

Similar responses to EQ-5D-3L by two elicitation methods: visual analogue scale and time trade-off

BackgroundHealth-related quality of life (HRQoL) is often measured using EQ-5D-3L by the elicitation methods of visual analogue scale (VAS) and time trade-off (TTO). Although many countries have constructed both national VAS and TTO value sets, the fact that VAS and TTO value sets produces different values bewilders researchers and policymakers. The aim of this study is to explore certain conditions which could yield similar value sets using VAS and TTO.MethodsA homogeneous sample of medical school students was selected to value 18 hypothetical health states using VAS and TTO methods. The 18 hypothetical health states were produced by orthogonal design (L18, 2*3^7). The range of rescaled values was transformed into − 1 ~ 0 ~ 1. The investigations via different methods were carried out by computer-assisted personal interviewing with a wash-time interval of 72 h. Value sets for VAS and TTO were constructed using general least square regression models. Independent variables were composed of 10 dummy variables from 5 dimensions and including or omitting both constant and N3 terms.ResultsThree hundred thirteen medical students participated. The mean age was 21.03 ± 0.44 years and 56.2% were female. The four regression models (for each method with and without constant and N3 terms) were all statistically significant (P < 0.05) with high goodness-of-fit (Adj. R2 > 0.94 and MAE < 0.033). Differences between the coefficients of the 10 dummy variables corresponding to each model were all less than 0.059. Pearson correlation coefficients between observed means and predicted values exceeded 0.981. Fitted curves of VAS and TTO largely coincided.ConclusionsVAS and TTO can generate similar responses under certain conditions, suggesting that the two valuation methods could be equivalent intrinsically. The VAS method appears a more valid approach for valuation in the general population due to its greater simplicity and feasibility.

Experience-Based Swedish TTO and VAS Value Sets for EQ-5D-5L Health States.

Although value sets for the five-level version of the generic health-related quality-of-life instrument EQ-5D are emerging, there is still no value set available in the literature based on time trade-off valuations made by individuals experiencing the valued health states. The aim of this study was to estimate experience-based value sets for the EQ-5D-5L for Sweden using time trade-off and visual analogue scale valuation methods. In a large, cross-sectional, population-based, self-administered postal health survey, the EQ-5D-5L descriptive system, EQ visual analogue scale and a time trade-off question were included. Time trade-off and visual analogue scale valuations of the respondent's current health status were used in statistical modelling to estimate a single-index value of health for each of the 3125 health states. Ordinary least-squares and generalised linear models were estimated with the main effect within each of the five dimensions represented by 20 dummy variables reflecting the additional decrement in value for levels 2-5 when the severity increases by one level sequentially beginning from having no problem. Interaction variables representing the occurrence of severity levels in at least one of the dimensions were tested: severity level 2 or worse (N2); severity level 3 or worse (N3); severity level 4 or worse (N4); severity level 5 (N5). A total of 896 health states (28.7% of the 3125 possible EQ-5D-5L health states) were reported by the 25,867 respondents. Visual analogue scale (n = 23,899) and time trade-off (n = 13,381) responders reported valuations of their currently experienced health state. The preferred regression models used ordinary least-squares estimation for both time trade-off and visual analogue scale values and showed consistency in all coefficients after combining certain levels. Levels 4 and 5 for the dimensions of mobility, self-care and usual activities were combined in the time trade-off model. Including the interaction variable N5, indicating severity level 5 in at least one of the five dimensions, made it possible to distinguish between the two worst severity levels where no other dimension is at level 5 as this coefficient is applied only once. In the visual analogue scale regression model, levels 4 and 5 of the mobility dimension were combined. The interaction variables N2-N4 were included, indicating that each of these terms reflect a statistically significant decrement in visual analogue scale value if any of the dimensions is at severity level 2, 3 or 4, respectively. Time trade-off and visual analogue scale value sets for the EQ-5D-5L are now available for Sweden. The time trade-off value set is the first such value set based on experience-based timetrade-off valuation. For decision makers with a preference for experience-based valuations of health states from a representative population-based sample, the reported value sets may be considered fit for purpose to support resource allocation decision as well as evaluating population health and healthcare performance.

Using the Choice Sequence in Time Trade-Off as Discrete Choices: Do the Two Stories Match?

ObjectivesThe EQ-5D-5L valuation protocol recommends combining time trade-off (TTO) and discrete choice experiments (DCEs). DCEs that include a duration attribute (DCETTO) allow modeling on the quality-adjusted life-year scale. Because the choice sequence in a TTO can be construed as a series of DCETTO, we used data from a single TTO study to investigate the extent to which DCE values match TTO values when based on identical preferences. MethodsIn a TTO design in which a fixed set of choices were administered without termination at preference indifference, 202 individuals each valued 10 EQ-5D health states. From identified indifference points, we estimated three sets of TTO values: (i) plotting means and (ii) applying censored regressions at −1 and 1. Using all strict preferences, we (iii) estimated DCETTO values with a logit model and a bootstrap procedure. ResultsEstimated DCETTO and TTO values agreed well at the severe end of the quality-adjusted life-year scale, but with decreasing severity, DCETTO values were higher than TTO-values, with the difference peaking at 0.37 for the mildest health state. Left-censoring TTO values at −1 worsen the agreement for the worst health states and did not affect health states. Right censoring at 1 improved the agreement for mild states. ConclusionsTTO and the DCETTO values estimated from the same preference data diverged, with increasing difference for milder health states. Although the values converged when applying censored regression at +1, we question the validity of this adjustment.

Influence of elicitation procedure and phrasing on health state valuations in experience-based time trade-off tasks among diabetes patients in China

PurposeOpen-ended and iteration-based time trade-off (TTO) tasks can both be used for valuation of health states. It has so far not been examined how the elicitation procedure affects the valuation of experience-based health states. The purpose of this study is to investigate the influence of elicitation procedure on experience-based health state values elicited by the TTO method.Methods156 Chinese adults with type 2 diabetes participated in face-to-face interviews with an open-ended or an iteration-based TTO task. The association between the type of TTO task and the valuation of health states was investigated through multiple linear regression analyses. A modified open-ended TTO task was also developed (n = 33) to test whether different phrasings of open-ended TTO tasks influence TTO values.ResultsHigher TTO values were observed in the original open-ended TTO task compared to the iteration-based task, which indicates that the elicitation procedure influences the valuation of health states. When the modified open-ended task was introduced, the difference between the two elicitation procedures was no longer statistically significant, suggesting that the phrasing and/or visual presentation of the TTO task may influence the valuation of health states.ConclusionsThe choice of elicitation procedure as well as the description of experience-based TTO tasks may influence the valuation of health states. Further research is warranted, also in other cultural contexts, to further explore these findings.

Effect of Reflection and Deliberation on Health State Values: A Mixed-Methods Study

BackgroundHealth economists ask members of the general public to value health states, but it is recognized that individuals construct their preferences during the valuation tasks. Conventional methods rely on one-off interviews that do not give participants time to reflect and deliberate on their preferences. ObjectiveThis study investigates the effect of reflection and deliberation on health state preferences using the EQ-5D questionnaire and time trade-off valuation method. MethodsA novel concurrent explanatory mixed-methods design is used to investigate the explanation for the quantitative findings. ResultsA total of 57 participants in the United Kingdom valued health states before and after a group-based deliberation exercise. There were large changes in health state values at the individual level, but the changes canceled out at the aggregate level. The mixed-methods findings suggest deliberation did not reveal new information or reduce inconsistencies in reasoning but rather focused on an exchange of personal subjective beliefs. In cases of disagreement, the participants accepted but did not adopt other participants' opinions. Participants remained uncertain about the relevance of their experiences and about their values. ConclusionsThe evidence suggests that reflection and deliberation, as designed in this study, are unlikely to result in large systematic changes of health state values. The uncertainties expressed by participants means future research should investigate whether preferences are informed or whether providing participants with more information helps them construct their preferences with more certainty. The mixed-methods design used is a promising design to help elucidate the reasons for quantitative findings.

Toward a Smaller Design for EQ-5D-5L Valuation Studies

BackgroundTo construct an EQ-5D-5L value set, the EuroQol Group developed a standard protocol named EuroQol Valuation Technology (EQ-VT), prescribing the valuation of 86 health states utilizing the composite time trade-off (cTTO) approach, and subsequently modeled the observed values to yield values for all 3125 states. ObjectiveA recent study demonstrated that a 25-state orthogonal design could provide as accurate predictions as the EQ-VT design applying visual analogue scale data. We aimed to test that design using time trade-off (TTO) data. MethodWe collected TTO values utilizing EQ-VT, orthogonal, and D-efficient designs. The EQ-VT design included 86 health states distributed over 3 blocks of 30 states with some duplicates. The orthogonal and D-efficient designs each comprised 1 block of 30 states. A total of 525 university students were asked to value a random block of health states using EQ-PVT (a PowerPoint replica of EQ-VT software), which generated 100 observations per health state in all 3 designs. We modeled data by design and compared the root mean square error (RMSE) between observed and predicted values within and across the designs. ResultsThe EQ-VT design had the lowest RMSE of 0.052; the RMSEs for the orthogonal and the D-efficient designs were 0.066 and 0.063, respectively. RMSE results between designs differed for more severe health states. Some coefficients differed between designs. ConclusionSmaller designs did not lead to significant increases in prediction errors when modeling TTO data (measuring 0.01 on a utility scale). Resource-constrained countries may use small designs for valuation studies, especially when other types of preference data, such as those from discrete choice experiments, are collected and modeled jointly.

Exploring the predictors of health valuations of EQ 5D 3L with a mixed-effects linear model

ABSTRACT Background Information about how individual characteristics influence preferences about health states valuation are scare. The purpose of this study is to identify predictors of the EuroQol with five dimensions and 3 levels – EQ 5D-3L time-tradeoff valuation. Research design and methods We analyzed a dataset with a probabilistic sample of 5774 individuals. Two sets of independent variables for testing were defined: a set of forced variables composed of 10 dummy variables for EuroQol levels 2 and 3 of each health dimension and a set of demographic variables. Results The strongest predictors of health valuation were the self-reported health state and the ‘belief in God,’ with 0.11 utility units for each VAS unit and 0.11 utility units for ‘yes’ for the ‘belief in God’ parameter.Age had an impact of 0.0190 utility units for each 10-year interval. Having children had a small effect (0.0338 utility units for ‘yes’), and the other characteristics studied had no significant impact. Conclusions People who believe in God (or the afterlife) and those of greater age seem to be less prone to forgoing life years to avoid health problems. In our sample, older individuals valued health state higher than younger individuals.

Valuation of EQ-5D-5L Health States in Poland: the First EQ-VT-Based Study in Central and Eastern Europe.

ObjectiveCost-utility analyses are becoming increasingly important in Central and Eastern Europe. We aimed to develop a Polish utility tariff for EQ-5D-5L health states.MethodsFace-to-face, computer-assisted interviews were collected in a representative sample. Each respondent followed a standardised protocol to collect ten composite time trade-off and seven discrete choice experiment observations. In the Bayesian approach, several model specifications were compared based on model fit, the usability of the final value set and how they reflect the elicitation procedure (e.g. censoring). A hybrid approach (using composite time trade-off and discrete choice experiment data) was employed in the final set, which was compared with the existing ones: EQ-5D-3L and EQ-5D-5L cross-walk.ResultsData from 1252 respondents (11,480 composite time trade-off valuations and 8764 discrete choice experiment pairs) were collected over the period June to October 2016. The final model accounted for random parameters, error scaling with fat tails, censoring at − 1, unwillingness to trade in time trade-off by the religious people and Cauchy distribution in discrete choice experiments. Pain/discomfort impacts the utility most: the disutility equals 0.575 when at level 5. In the value set, 4.4% of EQ-5D-5L states are worse than dead. The new value set has a comparable range (minimum of − 0.590 compared to − 0.523) and the same ordering of the first three dimensions (pain/discomfort, mobility, self-care) as the EQ-5D-3L value set and the EQ-5D-5L cross-walk value set. Moreover, it is more sensitive to a moderate decline in health.ConclusionsThe new value set supports consistency with past decisions in cost-utility studies, while offering a better assessment of even moderate improvements in health. It could represent an option for Central and Eastern Europe countries lacking their own value sets.Electronic supplementary materialThe online version of this article (10.1007/s40273-019-00811-7) contains supplementary material, which is available to authorized users.

Valuation of Quality Weights for EuroQol 5-Dimensional Health States With the Time Trade-Off Method in the Capital of Iran

BackgroundThe EuroQol 5-dimension (EQ-5D) is a standard instrument that is widely used for measuring health-related quality of life and quality-adjusted life years in economic evaluation of healthcare interventions. ObjectiveTo estimate a preference valuation set for EQ-5D 3-level (3L) health states from the perspective of the general population in the capital of Iran. MethodsEight hundred seventy adults aged ≥18 years were interviewed in Tehran (Iran's capital) from July to November 2013. The participants were selected by a stratified random sampling method and were interviewed face-to-face at their usual residence. Forty-two health states were selected and valued from the 243 states derived from the EQ-5D-3L instrument. Each respondent valued 11 health states using the time trade-off method. Generalized least squares regression with random effect was used to predict values for health states. ResultsThe analysis was performed for 846 respondents. The final model yielded the best fit for the time trade-off value at the individual level with an overall R2 of 0.45 and a mean absolute error of 0.214. The mean values for the 42 health states ranged from 0.934 for state 11121 to -0.142 for state 33333. ConclusionsThis study provided for the first time a value set for calculating quality-adjusted life years from the EQ-5D instrument in Iran. The Iranian EQ-5D-3L value set slightly differs from the value sets of the UK and the United States.

Disutility Study for Adult Patients with Moderate to Severe Crohn's Disease.

BackgroundCrohn’s disease (CD) treatments and associated adverse events (AEs) can be burdensome for patients. However, specific values which quantify the impact on health-related quality of life (HRQL) for economic evaluation are lacking.ObjectivesThis study aimed to elicit health utility values for AEs related to biologic treatment and surgical complications for CD in the UK.MethodsHealth states were developed by literature review and interviews with CD patients (n=6) and gastroenterologists (n=3). Draft health states were validated in cognitive debrief interviews with patients (n=4) and gastroenterologists (n=2). Treatment AEs were described with moderate-severe CD (reference state) and included hypersensitivity, injection site reactions, serious infection, lymphoma, and tuberculosis. Surgical complications were described following bowel surgery (reference state) and included anastomotic leak, wound infection, prolonged ileus/bowel obstruction, and intra-abdominal abscess. Health states were valued by 100 members of the general public who completed background questions, EQ-5D-3L, visual analogue scale rating task and time trade-off (TTO) interviews.ResultsThe mean TTO value for reference states ‘moderate to severe CD’ and ‘bowel surgery’ were 0.70 (SD=0.28) and 0.69 (SD=0.28). Participants rated lymphoma as the worst AE/surgical complication state (0.44, SD=0.37), followed by tuberculosis (0.47, SD=0.85) and anastomotic leak (0.48, SD=0.38). Values of other AE/surgical complication states ranged from 0.76 (hypersensitivity) to 0.56 (intra-abdominal abscess).ConclusionsThis study provides utility estimates for AE and surgical complication health states not previously assessed in the context of CD. As new treatments are emerging, it is important to include these influences on quality of life in any economic evaluation of treatments.

Does the Time Trade-Off Method Reflect Health-Related Quality of Life? A Mixed-Methods Analysis of Preference Measures 10 Years After Aneurysmal Subarachnoid Hemorrhage

To investigate if the time trade-off (TTO) method reflects health-related quality of life (HRQoL) 10 years after an aneurysmal subarachnoid hemorrhage (aSAH). A cross-sectional study with a mixed-methods approach was used to follow up 208 patients treated for aSAH. Data were collected with intramethod mixing; the quantitative data consisted of the EQ-5D-3L instrument and a TTO question, and the qualitative data comprised motivations to the TTO answer. The quantitative data were analyzed statistically and comparisons were made between participants willing to trade off years and those not willing to trade off years. The qualitative data were merged in a matrix and analyzed with manifest content analysis. Participants willing to trade off years scored significantly lower HRQoL, and the correlation between EQ-5Dindex and EQ VAS to TTO values were rs= 0.369 (P < 0.001) and rs= 0.345 (P < 0.001), respectively. In the content analysis, 4 categories emerged: perceived full health or satisfactory life; adaptability and managing strategies; the importance of hope and meaning in life; and unacceptable changes do not make life worth living. The results showed that several reasons other than health status were evident when expressing the willingness to trade off or not trade off life-years. Individuals willing to trade off years showed significantly poorer HRQoL; however the TTO method did not seem to fully reflect HRQoL. Most participants did not want to trade off years, despite their living with severe disability, making it difficult to fully rely on the TTO method in evaluation of medical outcome.

Do time trade-off values fully capture attitudes that are relevant to health-related choices?

Previous research has shown that demographics, beliefs, and self-reported own health influence TTO values. Our hypothesis is that attitudes towards length and quality of life influence TTO values, but should no longer affect a set of related choices that are based on respondents’ own TTO scores. A representative sample of 1339 respondents was asked their level of agreement to four statements relating to the importance of quality and length of life. Respondents then went on to value 4 EQ-5D 5L states using an online interactive survey and a related set of 6 pairwise health-related choice questions, set up, so that respondents should be indifferent between choice options. We explored the impact of attitudes using regression analysis for TTO values and a logit model for choices. TTO values were correlated with the attitudes and were found to have a residual impact on the choices. In particular, those respondents who preferred quality of life over length of life gave less weight to the differences in years and more weight to differences in quality of life in these choice. We conclude that although the TTO responses reflect attitudes, these attitudes continue to affect health-related choices.

Parallel Valuation: A Direct Comparison of EQ-5D-3L and EQ-5D-5L Societal Value Sets.

To compare and contrast EQ-5D-5L (5L) and EQ-5D-3L (3L) health state values derived from a common sample. Data from the 2017 US EQ-5D valuation study were analyzed. Value sets were estimated with random-effects linear regression based on composite time trade-off (cTTO) valuations for 3L and 5L health states with 2 approaches to model specification: main effects only and additional N3/N45 terms. Properties of the descriptive system and value set characteristics were compared by examining distributions of predicted index scores, ceiling effects, and single-level transition values from adjacent corner health states. Mean transition values were calculated for all predicted 3L and 5L health states and plotted against baseline index scores. A total of 1062 respondents were included in the analysis. The observed mean cTTO values for the worst possible 3L and 5L health states were -0.423 and -0.343, respectively. The range of scale was larger with the 3L, compared to the 5L, for both main effects and N term models. Values for the mildest 5L health states (range, 0.857-0.924) were similar to 11111 for the 3L. Parameter estimates for matched dimension levels differed by <|0.07| except for the most severe level of Mobility. For the main effects model, 3L mean transition values were greater for more severe baseline 3L index scores, whereas 5L mean transition values remained constant irrespective of the baseline index score. Compared to the 3L, the 5L exhibited a lower ceiling effect and improved measurement properties. There was a larger range of scale for the 3L compared to 5L; however, this difference was driven by differences in preference for the most severe level of problems in Mobility.

Health-related quality of life in patients with uveitis

Background/aimsTo measure health-related quality of life (HRQOL) in patients with uveitis using time trade-off (TTO) and standard gamble (SG) methods of direct utility analysis.MethodsConsecutive patients attending a tertiary referral uveitis...

PMU89 - EUROPEAN UNION 5 (EU5) NORMS FOR THE 3-LEVEL EQ-5D (EQ-5D-3L) QUESTIONNAIRE

. The EQ-5D is a generic measure of health-related quality of life that is widely applied for health economic and non-economic purposes. Population norms can be used to facilitate the interpretation of EQ-5D data. The objective of this study was to develop normative 3-level EQ-5D (EQ-5D-3L) values for the European Union 5 (EU5) countries. . EQ-5D-3L index values based on the time trade-off (TTO) were available for all EU5 countries (France, Germany, Italy, Spain, and United Kingdom) (n=21,425). Country-specific data sets were aggregated and weighted equally to facilitate the derivation of norms for gender and age groups. Sensitivity analyses included weighting by population and economy size. Norms were also calculated using the European visual analog scale-based value set (EurVAS). . Pooled mean (SD) TTO values for males/females were 0.969 (0.119)/0.962 (0.117) for ages 18-24; 0.965 (0.100)/0.955 (0.128) for ages 25-34; 0.942 (0.180)/0.935 (0.191) for ages 35-44; 0.931 (0.174)/0.918 (0.184) for ages 45-54; 0.895 (0.211)/0.874 (0.221) for ages 55-64; 0.901 (0.179)/0.838 (0.244) for ages 65-74; and 0.827 (0.246)/0.750 (0.299) for ages 75 and older. Mean values decreased and variance increased with age; females had slightly lower mean values than males across all age bands. The unequal weighting approaches produced similar point estimates with smaller variances. The means derived using these approaches most closely reflected values for Germany, which has a larger population and economy than other EU5 countries. Mean values for the EurVAS were slightly lower than those for the TTO-based index, though a similar pattern of means across demographic strata was observed. . Normative EQ-5D-3L values can be used to benchmark the outcomes of treated patients against the health of the general population. EU5 norms may be useful in research applications inferring to the EU as a whole, particularly when sample size precludes analysis at the country level.

Euthanasia, religiosity and the valuation of health states: results from an Irish EQ5D5L valuation study and their implications for anchor values

BackgroundThe Quality Adjusted Life Year influences the allocation of significant amounts of healthcare resources. Despite this surprisingly little research effort has been devoted to analysing how beliefs and attitudes to hastening death influence preferences for health states anchored at “dead” and “perfect health”. In this paper we examine how, inter alia, adherence to particular religious beliefs (religiosity) influences attitudes to euthanasia and how, inter alia, attitudes to euthanasia influences the willingness to assign worse than dead (WTD) values to health states using data collected as part of the Irish EQ5D5L valuation study.MethodsA sample of 160 respondents each supplied 10 composite time trade-off valuations and information on religiosity and attitudes to euthanasia as part of a larger national survey. Data were analysed using a recursive bivariate probit model in which attitudes to euthanasia and willingness to assign WTD values were analysed jointly as functions of a range of covariates.ResultsReligiosity was a significant determinant of attitudes to euthanasia and attitudes to euthanasia were a significant determinant of the likelihood of assigning WTD values. A significant negative correlation in errors between the two probit models was observed indicative of support for the hypothesis of endogeneity between attitudes to euthanasia and readiness to assign WTD values.ConclusionIn Ireland attitudes and beliefs play an important role in understanding health state preferences. Beyond Ireland this may have implications for: the construction of representative samples; understanding the values accorded health states and; the frequency with which value sets must be updated.

Time Trade-Off Value Set for EQ-5D-3L Based on a Nationally Representative Chinese Population Survey

ObjectivesTo obtain a nationally representative Chinese three-level EuroQol five-dimensional questionnaire value set based on the time trade-off (TTO) method. MethodsA multistage, stratified, clustered random nationally representative Chinese sample was used. The study design followed an adapted UK Measurement and Valuation of Health protocol. Each respondent valued 11 random states plus state 33333 and “unconscious” using the TTO method in face-to-face interviews. Three types of models were explored: ordinary least squares, general least squares, and weighted least squares models. ResultsIn total, 5939 inhabitants aged 15 years and older were interviewed. Of these, 5503 satisfactorily interviewed participants were included in constructing models. An ordinary least squares model including 10 dummies without constant and N3 had a mean absolute error of 0.083 and a correlation coefficient of 0.899 between the predicted and mean values. Goodness-of-fit indices of two models based on split subsample were similar. ConclusionsTTO values were higher in our study compared with those in a study carried out in urban areas, which is mirrored by the higher values in rural areas. Several other aspects, in addition to the valuation procedure, might have influenced the results, such as factors beyond demographic factors such as view on life and death and believing in an afterlife, which need further investigation. Future studies using the three-level EuroQol five-dimensional questionnaire should consider using this value set based on a nationally representative sample of the Chinese population.

What should we know about the person behind a TTO?

The time trade-off (TTO) method is widely used to obtain quality of life scores for health states, but its validity is not uncontested, for instance because TTO values for similar health states can differ substantially between studies. This could be caused by differences between studies in how the procedure is applied, but could also relate to differences in study samples.

Logical inconsistencies in time trade-off valuation of EQ-5D-5L health states: Whose fault is it?

IntroductionInconsistency in the time trade-off (TTO) task in EQ-5D-5L occurs when a respondent gives a higher value to a logically worse health state, the occurrence of inconsistency compromises the quality of the data. It is not yet clear which factors are associated with individual level inconsistency. Relating inconsistency to the characteristics of the respondent, interviewer, and the interview process could be helpful in understanding the causes of inconsistency. The objective of this paper is to discover the factors associated with individual level inconsistencies.MethodsTwenty interviewers interviewed 1,296 respondents and each respondent valued 10 health states using the EQ-VT platform in 5 cities in China. At the respondent level, inconsistency was identified in terms of severity and quantity and related to the respondent’s background characteristics, the time and iterations spent on the wheelchair example task, and the formal TTO tasks, using multilevel multinomial regression analyses. Interviewers’ impact on inconsistencies was analyzed using single level multinomial regression analyses.ResultsIn the full dataset, slight inconsistency was more related to the interview process (Time spent on TTO task: RRR = 1.246 with 95%CI: 1.076,1.441; time spent on Wheelchair example: RRR = 0.815 with 95%CI:0.699,0.952) while severe inconsistency was more related to respondent’s gender (Gender: RRR = 2.347 with 95%CI:1.429,3.855). One Interviewer (Interviewer 7: RRR = 7.335 with 95%CI:1.908,28.195) and interviewer’s experience (Sequence: RRR = 0.511 with 95%CI:0.385,0.678) in general showed strong influence over inconsistency in the TTO task.ConclusionIn conclusion, logical inconsistency in the valuation of EQ-5D-5L health states is associated not only with respondents’ characteristics but also with interviewers’ performance and the interview process. The role of interviewers and the importance of interviewer training may be more crucial than hitherto believed. This finding could be generalizable to other interviewer-administered health-state valuation study.