Testing the predective validity of the time trade-off and the Stardard Gamble

This paper tests the consistency of health utility measurements with individual preferences. We compare three methods, the time trade-off, the standard gamble and a version of the standard gamble that corrects for the deviations from expected utility modelled by prospect theory. Individual preferences are measured both through a ranking task and through a choice task. In decisions involving no risk the time trade-off is most consistent with people’s preferences with the standard gamble a close second. In decisions involving risk the corrected standard gamble is most consistent with people’s preferences. Our data do not support the common assumption in health economics that utility is transferable across decision contexts.Health utility measurement, QALYs,stardard gamble, time trade-off, prospect theory.

The influence of the Ratio Bias phenomenon on the elicitation of Standard Gamble utilities

This paper tests whether logically equivalent risk formats can lead to different health state utilities elicited by means of the standard gamble (SG) method. We compare SG utilities elicited when probabilities are framed in terms of frequencies with respect to 100 people in the population (i.e., X out of 100) with SG utilities elicited for frequencies with respect to 1,000 people in the population (i.e., Y out of 1,000). We found that utilities were significant higher when success and failure probabilities were framed as frequencies type “Y out of 1,000” rather than as frequencies type “X out of 100”. This framing effect, known as Ratio Bias, may have important consequences in resource allocation decisions.Framing effect, risk format, standard gamble, health state, dual-process theories.

Debiasing EQ-5D Tariffs. New estimations of the spanish EQ-5D value set under nonexpected utility

Este proyecto tiene como objetivo estimar las utilidades asociadas a los estados de salud definidos mediante el sistema EuroQol-5D a partir de la medición directa de las preferencias de una muestra de la población andaluza. Los valores obtenidos serán susceptibles de ser utilizados en el marco de estudios de evaluación económica de políticas sanitarias (análisis coste-utilidad) realizados en la comunidad andaluza y en el conjunto del estado. Para la valoración directa de un subconjunto de estados de salud se realizará una encuesta personal asistida por ordenador a una muestra representativa por sexo y cuotas de edad de la población española, extraída de la población residente en Andalucía. Los métodos que se aplicarán para obtener las preferencias y calcular las utilidades tratarán de corregir algunos de los sesgos que pueden afectar a las estimaciones existentes. Así, se adoptarán enfoques teóricos alternativos a los habitualmente empleados que permitirán relajar algunos de los supuestos que han sido puestos en cuestión a la luz de la evidencia empírica, como es el caso de la linealidad de la función de utilidad del tiempo de vida, la validez descriptiva de la teoría de la utilidad esperada o la separabilidad multiplicativa de las preferencias por cantidad y calidad de vida.EQ-5D, social tariff, utility curvature, probability weighting, rank-dependent utility, time trade-off, value lottery equivalence, certainlty equivalence

Validation and comparison of 15-D and EQ-5D-5L instruments in a Spanish Parkinson's disease population sample

Purpose: To contribute to the ongoing discussion on the choice of a preference-based health-related quality of life (HRQoL) instrument to be used in cost-effectiveness analysis by studying and comparing the validity, sensitivity and relative efficiency of 15-D and EuroQol 5D 5L (EQ-5D-5L) in a Spanish Parkinson’s disease (PD) population sample. Methods: One hundred and thirty-three volunteers were asked to complete an interview using 15-D and EQ-5D-5L. Spearman’s rank correlation coefficient (r) was used to test the convergent validity of these instruments with specific PD measures. Sensitivity and efficiency were compared using receiver operating characteristic (ROC) curves and relative efficiency statistic, respectively. Results: A strong correlation (r > 0.65; p 0.50; p < 0.001) was found between 15-D and EQ-5D-5L utilities with the EQ-VAS. The areas under the ROC of both instruments all exceeded 0.5 (p < 0.001). The 15-D instrument was 4.1–29.8 % less efficient at detecting differences between patients with optimal HRQoL, while this instrument was 11 % more efficient at detecting differences between patients at mild and moderate to strong severity of the PD symptoms. Conclusions: 15-D and EQ-5D-5L are showed to be valid and sensitivity generic HRQoL measures in Spanish PD patients with both instruments showing similar HRQoL dimension coverage and ceiling/floor effects. The 15-D has better efficiency and greater sensitivity to detect clinical changes in PD severity of the symptoms meanwhile the EQ-5D-5L is better to detect clinical HRQoL changes. Additionally, the EQ-5D-5L questionnaire requires less time than 15-D to be administered, and it might be more appropriate for studies conducted in Spain, since a country-specific “value set” is available for this instrument and not for the 15-D