Considering the potential implications for reimbursement decisions, understanding the validity of the TTO (time trade off) method and what influences TTO scores is important. In a TTO exercise, a respondent is asked to trade off length of life against quality of life. This is typically done by deriving a point of indifference between two streams of health: one involving living a longer period in some impaired health state, the other living a shorter period in perfect health. The derived point of indifference provides the value of the impaired health state relative to perfect health. To understand the validity of the TTO method and what influences TTO scores, understanding the influence of respondent characteristics on TTO scores is important, for example because of (i) sampling purposes, (ii) the ability to compare TTO scores across studies and populations, and (iii) understanding the observed TTO scores. Many respondent characteristics have the potential to influence TTO and corresponding quality-of-life weights, but in most cases their exact influence remains unclear.
- PhD student
- Promotor
- Promotor
- Date
- Thursday 21 Mar 2019, 15:30 - 17:30
- Type
- PhD defence
- Spoken Language
- Dutch
- Space
- Senate Hall
- Building
- Erasmus Building
- Location
- Campus Woudestein
This thesis investigated the influence of respondent characteristics through several empirical TTO studies. In all these studies, respondents from the general public answered TTO questions to value hypothetical health states. In addition, several respondent characteristics and attitudinal variables were collected in these studies, including demographic characteristics, future expectations regarding health and age of death, as well as beliefs about life and death.
Notwithstanding some limitations, the main aim of this thesis was to contribute to a better understanding of which respondent characteristics and attitudinal factors influence TTO responses. Overall, this thesis provided additional supportive evidence that TTO responses are affected by several respondent characteristics, in particular subjective life expectancy, but also attitudes and beliefs regarding future health, significant others, like partner or children and death may influence TTO scores as well.. Besides increasing our understanding of TTO responses, such respondent characteristics may also be important in the context of sampling, especially when comparing results from different TTO studies, or aiming to derive representative health state valuations, for instance to be used for national tariffs.
In conclusion, while much more work can and should be done in this area, this thesis hopes to have contributed to a better understanding of the influence of ‘the person behind the TTO’ on observed health state valuations, and the relevance of doing so even better in the future.
- More information
This PhD defence is in Dutch.
