Patterns of responses in time trade-off studies: a latent class analysis of health states worse than dead

Facets of TTO tasks such as states WTD may introduce an additional cognitive burden on participants and impact on congruence. However, incongruence was observed even within ostensibly perfectly congruent responses; conversely incongruent response patterns showed some internal coherence. Removing the latter in favour of the former may therefore also introduce bias. A balance may need to be struck between sacrificing perfect congruence and the inclusion of some incongruence to achieve greater representativeness of health state utilities.