THE EFFECT OF FRAMING OF DEATH ON HEALTH STATE VALUES OBTAINED FROM DISCRETE CHOICE EXPERIMENTS
Method: An experiment with 4 distinctly different framings was conducted among a Dutch nationally representative sample of 1200 respondents. These framings comprise both DCE approaches (i.e. DCEduration and DCEdeath) with and without the addition of lead time (LT) to the EQ5D5Lhealth profiles. A Bayesian efficient design consisting of 8 sets of 30 (matched pairwise) choice tasks was used. The design was jointly optimized for all framings, thereby keeping all aspects of the DCE design except for the framing constant. Respondents were randomly assigned to one of the 4 study arms. Mixed logit models were used to analyze the DCE data, and the resulting estimates of the utility decrements associated with the severity levels within each dimension were compared between the 4 arms to establish the impact of the framing effects.
Results: The estimation results revealed substantial framing effects. While the DCE death approach classified just 8% of the health states as worse than death, much higher percentages were found in the other arms: 28% (duration), 57% (LT-death) and 81% (LT-duration). Relative distances between health states on the latent scale were not affected by adding LT, but anchoring on death altered the values. We observed less dispersion for mild to moderate states, and a more stretched distribution for severe states.
Conclusion: Estimation results were substantially altered by the framing of death as explicit or implicit, and immediate or postponed. These framing effects may help to explain the commonly observed discrepancies between values derived using Time Trade Off and the popular DCE duration approach. While one may argue against the use of a death alternative in DCE tasks for health state valuation on basis of theoretical and statistical considerations, it would seem to be an essential component for those who aim to reconcile DCE and TTO results.