Estimating an EQ-5D-5L Value Set for China.

Our objective was to compare the time trade-off (TTO) values of EQ-5D-3L health states elicited from Singaporeans with and without type 2 diabetes mellitus (T2DM) and T2DM patients with and without complications. The TTO values of ten EQ-5D-3L health states were elicited from a consecutive sample of T2DM patients and a general Singaporean population sample using similar valuation protocols. In face-to-face interviews, T2DM patients and members of the general population were asked to value five and ten health states, respectively. The difference in TTO values between the two samples and between T2DM patients with and without complications was examined using multiple linear regression models. A total of 109 T2DM patients and 46 individuals without T2DM provided data. All ten health states considered, the mean TTO value was -0.02 for the general population sample and -0.04 for T2DM patients, with the unadjusted and adjusted difference being -0.06 (95 % confidence interval [CI] -0.16, 0.03) and 0.02 (95 % CI -0.12, 0.15). The general population sample had systematically lower TTO values for mild health states, with the adjusted difference being -0.13 (95% CI -0.25, -0.02); while the two samples had similar TTO values for severe health states, with the adjusted difference being 0.02 (95% CI -0.16, 0.19). T2DM patients without complications had systematically lower TTO values than those with complications, with the adjusted difference being -0.10 (95% CI -0.23, 0.03). It appears that diabetes and its complications affect patients' valuation of health states. Hence, the EQ-5D-3L health-state values based on the general population may underestimate the utility of health interventions for T2DM.

The standard gamble (SG) method is the gold standard for valuing health states as a utility, although it is accepted that it is difficult to valuate health states. This study was conducted in order to compare the SG with the rating scale (RS) and time trade-off (TTO) techniques in terms of their feasibility, comparability, and reliability in a valuation survey of the general Korean population. Five-hundred members of the general Korean population were recruited using a multi-stage quota sampling method in Seoul and its surrounding areas, Korea. Respondents evaluated 9 EQ-5D-5L health states using a visual analogue scale (VAS), SG, and TTO during a personal interview. Feasibility was assessed in aspects of the level of difficulty, administration time, and inconsistent responses. Comparability was evaluated using intraclass correlation coefficient (ICC) and the Bland-Altman approach. Test-retest reliability was analyzed using the ICC. Of the three methods, VAS was the easiest and quickest method to respond. The SG method did not differ significantly compared to the TTO method in administration time as well as the level of difficulty. The SG and TTO values were highly correlated (r=0.992), and the average mean difference between the SG and the TTO values was 0.034. The ICCs of the VAS, SG, and TTO scores were 0.906, 0.841, and 0.827, respectively. This study suggests that the SG method compared with the VAS and TTO method was feasible and offered a reliable tool for population-based, health state valuation studies in Korea.

Background and aimsTo elicit utility values for five health states corresponding to increasing severity of hepatic encephalopathy, from members of the general public in the UK. The health states studied were Conn grades 0, 1, 2, 3 and 4.MethodsInterviewer-administered time trade-off (TTO) and standard gamble (SG) utilities were elicited for the five health states from a random sample of 200 members of the general public in the UK, using health state descriptions validated by clinicians and members of the general public.ResultsRespondents’ mean age was 49.5 years and 49% were female. Mean utilities were 0.962 (TTO) and 0.915 (SG) for Conn grade 0; 0.912 (TTO) and 0.837 (SG) for Conn grade 1; 0.828 (TTO) and 0.683 (SG) for Conn grade 2; 0.691 (TTO) and 0.489 (SG) for Conn grade 3; and 0.429 (TTO) and 0.215 (SG) for Conn grade 4. The TTO and SG values between the five Conn grades were significantly different (p < 0.001). Additionally, the TTO value was significantly higher than the SG value for the corresponding state (p <0.0001).ConclusionThese findings quantify how different Conn grades and level of response to treatment may impact on the health-related quality of life of patients with hepatic encephalopathy. There were greater preference values for lower levels of disease, with the highest value associated with Conn grade 0. These health state preference values can be used to estimate the outcomes of different interventions for hepatic encephalopathy in terms of quality-adjusted life years.

The feasibility, validity and reliability of the Time Trade-Off (TTO) and Visual Analogue Scale (VAS) methods in obtaining preference values for health states were compared in a random sample of the Spanish population (n = 294). Respondents valued 43 EuroQol-5D health states in face-to-face interviews. Convergent validity was assessed by examining the relationship between values, and the effect of sociodemographic and health variables on values was used as a means of assessing construct validity. Test-retest reliability was analysed in a subgroup of 50 respondents, using the intraclass correlation coefficient (ICC) and generalisability theory. Rates of non-response and missing data were low on both methods, though the VAS took considerably less time to administer. VAS and TTO values correlated highly (r = 0.92), though there were differences in the ordering of health states between methods, and in the number of health states rated worse than death. VAS values were compressed into a considerably smaller valuation space than TTO values. Respondents in higher educational categories assigned higher TTO values to 12 health states. Mean ICCs (95% CI) at individual level were 0.90 (0.88-0.92) and 0.84 (0.81-0.87) for the VAS and TTO, respectively. Generalisability analysis showed variance due to time to be 0 for both methods. In conclusion, the VAS was more feasible and slightly more reliable than the TTO, whilst doubt can be cast on the degree of convergent validity existing between the two methods. The compression of VAS values means that the TTO is likely to discriminate better between health states, and it may have greater construct validity if results from larger samples confirm that there are genuine differences between sociodemographic subgroups.

Testing 2 Alternative Time Trade-Off Methods for Valuation of Children’s Health States

Health state values are by convention anchored to 'perfect health' and 'death.' Attitudes toward death may consequently influence the valuations. We used attitudes toward euthanasia (ATE) as a sub-construct for attitudes toward death. We compared the influence on values elicited with time trade-off (TTO), lead-time TTO (LT-TTO) and visual analogue scale (VAS).Since the 'death' anchor is most explicit in TTO, we hypothesized that TTO values would be most influenced by ATE. Respondents valued eight EQ-5D health states with VAS, then TTO (n=328) or LT-TTO (n=484). We measured ATE on a scale from -2 (fully disagree) to 2 (fully agree) and used multiple linear regressions to predict VAS, TTO, and LT-TTO values by ATE, sex, age, and education. A one-point increase on the ATE scale predicted a mean TTO value change of -.113 and LT-TTO change of -.072. Demographic variables, but not ATE, predicted VAS values. TTO appears to measure ATE in addition to preferences for health states. Different ways of incorporating death in the valuation may impact substantially on the resulting values. 'Death' is a metaphysically unknown concept, and implications of attitudes toward death should be investigated further to evaluate the appropriateness of using 'death' as an anchor.

Little is known about whether health-state preferences differ among Chinese populations. This study compared the preference values for EQ-5D-5L health states between mainland Chinese and Singaporean Chinese. The preference values for ten EQ-5D-5L health states were elicited from general population samples of mainland Chinese and Singaporeans. In computer-assisted self-interviews, each participant completed five time trade-off (TTO) tasks to value five different EQ-5D-5L health states. The difference in TTO values between mainland Chinese and Singaporean Chinese was examined using random-effects linear regression and logistic regression models. A total of 194 eligible mainland Chinese and 145 eligible Singaporean Chinese provided data for this study. All ten health states considered, the mean TTO value was 0.18 for Singaporean Chinese and 0.35 for mainland Chinese, with the unadjusted and adjusted difference [95% confidence interval (CI)] being -0.17 (-0.28, -0.07) and -0.16 (-0.27, -0.05). Singaporean Chinese had substantially lower TTO values than mainland Chinese for states with severe or extreme problems, with the adjusted difference being -0.30 (95% CI -0.42, -0.17). On the other hand, Singaporean Chinese and mainland Chinese had similar TTO values for states with mild or moderate problems, with the adjusted (95% CI) difference being 0.04 (-0.07, 0.15). Logistic regression analysis showed that Singaporean Chinese were more likely to rate health states with severe or extreme problems as worse than death compared to mainland Chinese. Mainland Chinese and Singaporean Chinese have different preferences for EQ-5D-5L health states, supporting the development of local value sets for the EQ-5D-5L instrument for the two populations.

This study elicited time trade-off (TTO) and standard gamble (SG) preference values associated with four health states corresponding to response levels in chronic phase chronic myeloid leukemia (CML) from members of the general public in the UK (n = 235). Health states studied were treatment-free remission (TFR), complete molecular response (CMR, i.e. undetectable disease on treatment), molecular response and reappearance of detectable disease (i.e. relapse from TFR to molecular response requiring treatment). TFR was the most preferred health state (mean utility of 0.97 [TTO] and 0.87 [SG]) followed by CMR (mean utility of 0.96 [TTO] and 0.85 [SG]) followed by molecular response (mean utility of 0.94 [TTO] and 0.80 [SG]) followed by reappearance of detectable disease (mean utility of 0.90 [TTO] and 0.72 [SG]). SG values were significantly lower than TTO values (p < 0.001). The study demonstrated that different treatment responses may impact on the health-related quality of life of patients with chronic phase CML.

An Empirical Study of Two Alternative Comparators for Use in Time Trade-Off Studies

Assessing the comparative feasibility, acceptability and equivalence of videoconference interviews and face-to-face interviews using the time trade-off technique

Estimating an EQ-5D Value Set for Malaysia Using Time Trade-Off and Visual Analogue Scale Methods

Valuing health status using VAS and TTO: What lies behind the numbers?

BackgroundIn survey studies on health-state valuations, ordinal ranking exercises often are used as precursors to other elicitation methods such as the time trade-off (TTO) or standard gamble, but the ranking data have not been used in deriving cardinal valuations. This study reconsiders the role of ordinal ranks in valuing health and introduces a new approach to estimate interval-scaled valuations based on aggregate ranking data.MethodsAnalyses were undertaken on data from a previously published general population survey study in the United Kingdom that included rankings and TTO values for hypothetical states described using the EQ-5D classification system. The EQ-5D includes five domains (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) with three possible levels on each. Rank data were analysed using a random utility model, operationalized through conditional logit regression. In the statistical model, probabilities of observed rankings were related to the latent utilities of different health states, modeled as a linear function of EQ-5D domain scores, as in previously reported EQ-5D valuation functions. Predicted valuations based on the conditional logit model were compared to observed TTO values for the 42 states in the study and to predictions based on a model estimated directly from the TTO values. Models were evaluated using the intraclass correlation coefficient (ICC) between predictions and mean observations, and the root mean squared error of predictions at the individual level.ResultsAgreement between predicted valuations from the rank model and observed TTO values was very high, with an ICC of 0.97, only marginally lower than for predictions based on the model estimated directly from TTO values (ICC = 0.99). Individual-level errors were also comparable in the two models, with root mean squared errors of 0.503 and 0.496 for the rank-based and TTO-based predictions, respectively.ConclusionsModeling health-state valuations based on ordinal ranks can provide results that are similar to those obtained from more widely analyzed valuation techniques such as the TTO. The information content in aggregate ranking data is not currently exploited to full advantage. The possibility of estimating cardinal valuations from ordinal ranks could also simplify future data collection dramatically and facilitate wider empirical study of health-state valuations in diverse settings and population groups.

General population preferences for standardized health states are usually obtained for chronic health states. The primary objective of this study was to analyze the feasibility and validity of using time trade-off (TTO) and a visual analog scale (VAS) to elicit preference values for temporary health states (THS=1 year duration, followed by normal health). Subjects were a random sample (n=300) of the general population. 43 health states generated by the EuroQo-5D were valued. The VAS proved slightly more feasible than the TTO. At aggregate level, correlations between VAS and TTO values were high (Spearman r=0.98), and VAS ratings had slightly greater internal consistency and agreement with rank order preferences than the TTO. TTO values were higher than VAS values, and compression of TTO values suggested substantial reluctance to trade. The effect of age on values was reversed between methods, with older respondents scoring higher on the VAS and lower on the TTO, than other age groups. In conclusion, although the VAS proved to be slightly more feasible than the TTO, with slightly greater empirical validity, further research using a wider range of methods to test validity is required before a definitive conclusion on the relative empirical validity of the two valuation techniques can be drawn.

PurposeTo estimate Swedish experience-based value sets for EQ-5D health states using general population health survey data.MethodsApproximately 45,000 individuals valued their current health status by means of time trade off (TTO) and visual analogue scale (VAS) methods and answered the EQ-5D questionnaire, making it possible to model the association between the experience-based TTO and VAS values and the EQ-5D dimensions and severity levels. The association between TTO and VAS values and the different severity levels of respondents’ answers on a self-rated health (SRH) question was assessed.ResultsAlmost all dimensions (except usual activity) and severity levels had less impact on TTO valuations compared with the UK study based on hypothetical values. Anxiety/depression had the greatest impact on both TTO and VAS values. TTO and VAS values were consistently related to SRH. The inclusion of age, sex, education and socioeconomic group affected the main effect coefficients and the explanatory power modestly.ConclusionsA value set for EQ-5D health states based on Swedish valuations has been lacking. Several authors have recently advocated the normative standpoint of using experience-based values. Guidelines of economic evaluation for reimbursement decisions in Sweden recommend the use of experience-based values for QALY calculations. Our results that anxiety/depression had the greatest impact on both TTO and VAS values underline the importance of mental health for individuals’ overall HRQoL. Using population surveys is in line with recent thinking on valuing health states and could reduce some of the focusing effects potentially appearing in hypothetical valuation studies.Electronic supplementary materialThe online version of this article (doi:10.1007/s11136-013-0496-4) contains supplementary material, which is available to authorized users.