Background Standard methods of assigning utility values to health states are imperfect and found difficult or impossible by many respondents.
This pilot study examined the utility values produced by the same person for the same health state using different methods, and whether existential beliefs affected measures involving timing or risk of death differentially. It also aimed to evaluate the acceptability of a questionnaire examining these measures.
Methods Using snowball sampling, 78 medical and non-medical professionals opted-in to receive an anonymous questionnaire. This contained a health state described by the EuroQoL-5D scale and four questions to elicit utility values for this state using the time trade off (TTO), Standard Gamble (SG), person trade off (PTO) and visual analogue scale (VAS) methods. A box labelled “too complicated//can’t be bothered” was placed beside each question with text stressing that this was a useful response and requesting the questionnaire be returned even if only this box was filled in.
Respondents were then asked to tick any beliefs about death which they themselves held from a list containing common beliefs (heaven, hell, reincarnation, nothingness etc).
In statistical analysis, means for the HRQOL value elicited by each method were compared and correlation coefficients between questions calculated for the whole sample and for doctors and other professionals separately. Existential beliefs were collapsed into death as nothingness v possibility of heaven and hell/judgement. Subgroup analysis between these groups used difference in the means and the F test for significance testing.
Results There was a 52% response rate. Most respondents found the tasks difficult, with the TTO having the highest completion rate (95%) and the PTO the lowest (67%). The correlation coefficients between the utility scores produced by different measures by the same individual were poor (range 0.2 – 0.25). Existential beliefs divided into belief in both heaven and hell/judgement and nothingness/uncertainty. The only statistically significant difference between utility estimates produced by the two groups was in the standard gamble (0.172, p value 0.004).
Asked how they had come to their answers, 23% reported “guessed” and 35% “instinct”. 39% had thought it out.
No respondent was offended by questions about existential beliefs. Most comments were protests about the paucity of information in the scale (16) or difficulty of the questions (10).
Conclusion HRQOL values elicited by different methods for the same health state from the same individual correlate poorly. Questions remain concerning the impact of existential beliefs on methods using timing or risk of death.
- QALYs Methods Ethics