Immediate Death: Not So Bad If You Discount the Future but Still Worse than It Should Be

Objectives Discrete choice experiments (DCEs) as a valuation method require preferences to be anchored on the quality-adjusted life-year scale, usually through tasks involving choices between immediate death and various impaired health states or between health states with varying durations of life. We sought to determine which anchoring approach aligns best with the composite time tradeoff (cTTO) method, with a view to informing a valuation protocol that uses DCEs in place of the cTTO. Methods A total of 970 respondents from Trinidad and Tobago completed a DCE with duration survey. Tasks involved choosing between 2 lives with identical durations, followed by a third option, representing either full health for a number of years or immediate death. Data were analyzed using mixed logit models, both with and without exponential discounting for time preferences. Results Assuming linear time preferences, the estimated utility of immediate death was −2.1 (95% credible interval [CrI] −3.2 to −1.2) versus −0.28 (95% CrI −0.47, −0.10) when allowing for nonlinear time preferences. Under linear time preferences, the predicted health-state values anchored on duration had range (−1.03, 1) versus (0.34, 1) when anchored on immediate death. The ranges under nonlinear time preferences were (−0.54, 1) versus (−0.22, 1). The estimated discount parameter was 23% (95% CrI 22% to 25%). Conclusions The nonzero discount parameter indicates that time preferences were nonlinear. Nonlinear time preferences anchored on duration provided the closest match to the benchmark EQ-VT cTTO values in Trinidad and Tobago, whose range was (−0.6, 1). Thus, DCE with duration can provide similar values to cTTO provided that nonlinear time preferences are accounted for and anchoring is based on duration. Highlights Time preferences for health states in Trinidad and Tobago were nonlinear. In discrete choice tasks, we show that immediate death has a utility less than zero. DCE utilities under nonlinear time preferences with anchoring on duration agreed well with cTTO utilities.