How do individuals value worse-than-dead EQ-5D-5L health states in composite time trade-off tasks? A qualitative study.

Abstract

Objectives: Limited knowledge exists regarding individuals' thought processes when valuing health states using the composite time trade-off (cTTO) tasks, particularly for health states considered as worse-than-dead (WTD). This study aims to explore the reasons for WTD perception, the strategies respondents employ to value WTD states, and the challenges they face during cTTO tasks.

Methods: This qualitative investigation was embedded within a methodological EQ-5D-5L valuation study involving the general public in Singapore, where respondents completed seven cTTO and seven novel TTO tasks. Semi-structured interviews were conducted with respondents who assigned WTD values to one or more health state in the cTTO tasks. Interviews were recorded, transcribed verbatim, and analysed using framework analysis.

Results: Nineteen respondents were interviewed (age range: 21-71 years old). Respondents identified a range of interconnected factors leading to WTD valuation, including health state and its duration, personal beliefs and circumstances, and consequences of poor health. While respondents usually considered these factors thoroughly and were capable of complex trading-off between life years and health, some respondents resorted to heuristic strategies to simplify the valuation process, including attribute non-attendance, affect heuristic, and elimination-by-aspects strategies. Respondents encountered various difficulties when they complete the cTTO tasks, including identifying the indifference point, transitioning from conventional TTO to lead-time TTO, and interpreting and imagining health states.

Conclusion: This study provides insights on how individuals value WTD health states in cTTO tasks. It suggests that cTTO needs improvement, and provides insights into how to improve the design of valuation tasks for severe health states.