José María Abellán-Perpiñán

A Consistency Test of the Time Trade-Off

This paper tests the internal consistency of time trade-off utilities. We find significant violations of consistency in the direction predicted by loss aversion. The violations disappear for higher gauge durations. We show that loss aversion can also explain that for short gauge durations time trade-off utilities exceed standard gamble utilities. Our results suggest that time trade-off measurements that use relatively short gauge durations, like the widely used EuroQol algorithm (Dolan 1997), are affected by loss aversion and lead to utilities that are too high.

The predictive validity of prospect theory versus expected utility in health utility measurement

Most health care evaluations today still assume expected utility even though the descriptive deficiencies of expected utility are well known. Prospect theory is the dominant descriptive alternative for expected utility. This paper tests whether prospect theory leads to better health evaluations than expected utility. The approach is purely descriptive: we explore how simple measurements together with prospect theory and expected utility predict choices and rankings between more complex stimuli. For decisions involving risk prospect theory is significantly more consistent with rankings and choices than expected utility. This conclusion no longer holds when we use prospect theory utilities and expected utilities to predict intertemporal decisions. The latter finding cautions against the common assumption in health economics that health state utilities are transferable across decision contexts. Our results suggest that the standard gamble and algorithms based on, should not be used to value health.

Cost-utility analysis of a 12-week whole-body vibration based treatment for people with type 2 diabetes: reanalysis of a RCT in a primary care context

• Whole Body Vibration (WBV) has been exhibited to be effective as a co-adjuvant treatment for type 2 diabetes (T2DM) patients in primary care.

Converting Parkinson-Specific Scores into Health State Utilities to Assess Cost-Utility Analysis

ObjectivesThe aim of this study was to compare the Parkinson’s Disease Questionnaire-8 (PDQ-8) with three multi-attribute utility (MAU) instruments (EQ-5D-3L, EQ-5D-5L, and 15D) and to develop mapping algorithms that could be used to transform PDQ-8 scores into MAU scores.MethodsA cross-sectional study was conducted. A final sample of 228 evaluable patients was included in the analyses. Sociodemographic and clinical data were also collected. Two EQ-5D questionnaires were scored using Spanish tariffs. Two models and three statistical techniques were used to estimate each model in the direct mapping framework for all three MAU instruments, including the most widely used ordinary least squares (OLS), the robust MM-estimator, and the generalized linear model (GLM). For both EQ-5D-3L and EQ-5D-5L, indirect response mapping based on an ordered logit model was also conducted. Three goodness-of-fit tests were employed to compare the models: the mean absolute error (MAE), the root-mean-square error (RMSE), and the intra-class correlation coefficient (ICC) between the predicted and observed utilities.ResultsHealth state utility scores ranged from 0.61 (EQ-5D-3L) to 0.74 (15D). The mean PDQ-8 score was 27.51. The correlation between overall PDQ-8 score and each MAU instrument ranged from − 0.729 (EQ-5D-5L) to − 0.752 (EQ-5D-3L). A mapping algorithm based on PDQ-8 items had better performance than using the overall score. For the two EQ-5D questionnaires, in general, the indirect mapping approach had comparable or even better performance than direct mapping based on MAE.ConclusionsMapping algorithms developed in this study enable the estimation of utility values from the PDQ-8. The indirect mapping equations reported for two EQ-5D questionnaires will further facilitate the calculation of EQ-5D utility scores using other country-specific tariffs.

Reducing preference reversals: The role of preference imprecision and nontransparent methods

Preferences elicited with matching and choice usually diverge (as characterised by preference reversals), violating a basic rationality requirement, namely, procedure invariance. We report the results of an experiment that shows that preference reversals between matching (Standard Gamble in our case) and choice are reduced when the matching task is conducted using nontransparent methods. Our results suggest that techniques based on nontransparent methods are less influenced by biases (i.e., compatibility effects) than transparent methods. We also observe that imprecision of preferences influences the degree of preference reversals. The preference reversal phenomenon is less strong in subjects with more precise preferences.

VALIDATION AND COMPARISON OF EQ-5D-3L AND SF-6D INSTRUMENTS IN A SPANISH PARKINSON´S DISEASE POPULATION SAMPLE.

INTRODUCTION generic, preference-based Health- Related Quality of Life instruments are receiving growing attention in health-care decision-making process. In spite of this, to our knowledge, EQ-5D and SF-6D have never been compared in a Parkinson´s disease population sample. OBJECTIVE the aim of this paper was to assess the psychometric properties of both instruments in a Spanish PD population sample. METHODS a total sample of 133 patients were interviewed using EQ-5D-3L and SF-6D. The validity, level of agreement and sensitivity of both instruments were computed and then compared. The Spanish tariff has been used in both instruments. RESULTS utilities of EQ-5D-3L and SF-6D have shown a strong correlation (r >0.50 and p<0.001) with the summary score of the PDQ-8 and the EQ-VAS score. Significant differences were observed in the stages III-IV of the Hoehn & Yahr stage. SF-6D had 51% higher efficiency than EQ-5D at detecting differences in symptoms severity. DISCUSSION both EQ-5D-3L and SF-6D seem to be adequate generic Health-Related Quality of Life measures in terms of validity and sensitivity. CONCLUSION EQ-5D-3L presents greater ceiling and floor effects than the SF-6D instrument in this sample. Besides, the instrument SF-6D was better at detecting changes in symptoms severity compared with EQ-5D-3L.