Who Prefers Death to Life in Composite Time Trade-Off Interviews and Why: A Mixed-Methods Analysis of the Singapore EQ-5D-5L Valuation Study

OBJECTIVES: The EuroQol Valuation Technology uses a composite time trade-off (cTTO) design with a 20-year timeframe, including 10 years in full health, to evaluate states worse than death, with values bounded at -1. Many EQ-5D-5L valuation studies report a high frequency of "-1" values. The factors behind this death-preferring response are unclear. This study aims to explore the respondent characteristics associated with "-1" cTTO values in a Singapore EQ-5D-5L valuation study and to explore the reasoning behind this preference.

METHODS: Five hundred adult Singaporeans were quota-sampled by age, sex, ethnicity, and education. Participants completed 20 cTTO tasks through computer-assisted personal interviews. Closed-ended questions assessed respondents’ priorities during cTTO tasks, and open-ended questions explored their reasoning. Two-part models and qualitative content analysis were used to identify factors associated with "-1" values and to understand the underlying motivations, respectively.

RESULTS: The study observed a 16.1% occurrence of "-1" values. Participant characteristics including age, education, marital status, and caregiving experience were correlated with "-1" assignments in simple regression. However, only age remained significant in multivariable analysis, with middle-aged participants being more likely to assign the -1 value (β: 1.07, 95% CI: 0.05, 2.08). Key considerations included physical, mental, and financial burdens, with middle-aged participants frequently citing the desire to avoid imposing these burdens on others as a primary reason for their preference. The middle-aged group also cited financial concerns, while the young and old focused on the loss of enjoyment and dignity, respectively.

CONCLUSIONS: The preference for immediate death over living in very poor health states is common among middle-aged Singaporeans. This preference is driven by concerns about burdening family members, perhaps due to their dual caregiving responsibilities. Our study validates the very low EQ-5D values in Singapore and may explain the high frequency of -1 values in other Asian EQ-5D studies.