Thirty down, only ten to go?! Awareness and influence of a 10-year time frame in TTO

摘要

Background Time trade-off (TTO) exercises typically present respondents with a limited time horizon, for example 10 years, thus implicitly considerably reducing remaining life expectancy for the average respondent. It is unclear how this affects health state valuations. Aim The aim of the study is to investigate how awareness of the reduced life span implied by a 10-year TTO affects health state valuations, using an experimental design. Methods Two Web-based questionnaires (Q1 and Q2) were administered in a sample representative of the Dutch population. Both questionnaires contained three 10-year TTO exercises valuing three distinct health states, specified using the EQ-5D. Q1 used a TTO instruction not explicitly emphasizing the fact that remaining life expectancy was reduced to 10 years, while in Q2 respondents were explicitly made aware of this fact by emphasizing their implied age of death. Respondents answering Q1 were asked retrospectively whether they had been aware of their reduced life span due to the 10-year TTO.