Assessing a dire fate: Standard gamble and time trade-off utilities for states worse than dead

Health utilities, which reflect how people value health conditions, are often elicited using the composite time trade-off (cTTO) method. This asks people how many years they would give up to avoid living in impaired health states. However, cTTO performs inadequately for states considered worse than being dead (WTD): more severe states do not necessarily receive lower utility. This study (i) explores whether this low sensitivity can be addressed by using ‘unified’ methods—methods that do not require separate approaches for eliciting utilities for states considered WTD, and (ii) investigates if the low sensitivity problem extends to risk-based methods such as the standard gamble (SG)—a method where participants choose between living with a health condition or taking a risky treatment. We ran an experiment with 198 participants randomized to one of four arms. One arm used cTTO followed by lead-time TTO (LT-TTO), which applies the same method for WTD and BTD (better than dead) states. The other three arms used variations of SG including a unified variant of the SG to explore the performance of risk-based and unified methods. Our results show that for both SG and TTO, unified procedures have improved sensitivity, i.e. they display a negative correlation between severity and utility for WTD states. However, the LT-TTO, compared to the cTTO, increases the number of WTD states and leads to lower utilities.