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The way that you do it? An elaborate test of procedural invariance of TTO, using a choice-based design.

Attema AE, Brouwer WB - Eur J Health Econ (2011)

Bottom Line: An important problem with this method is that results have been found to be responsive to the procedure used to elicit preferences.We find no violations of procedural invariance except for the shortest gauge duration.The results for CPTO are more troublesome: TTO scores depend on gauge duration, reinforcing the evidence reported when using the conventional procedure.

View Article: PubMed Central - PubMed

Affiliation: iBMG/iMTA, Erasmus University, PO Box 1738, 3000, DR, Rotterdam, The Netherlands. attema@bmg.eur.nl

ABSTRACT
The time tradeoff (TTO) method is often used to derive Quality-Adjusted Life Year health state valuations. An important problem with this method is that results have been found to be responsive to the procedure used to elicit preferences. In particular, fixing the duration in the health state to be valued and inferring the duration in full health that renders an individual indifferent, causes valuations to be higher than when the duration in full health is fixed and the duration in the health state to be valued is elicited. This paper presents a new test of procedural invariance for a broad range of time horizons, while using a choice-based design and adjusting for discounting. As one of the known problems with the conventional procedure is the violation of constant proportional tradeoffs (CPTO), we also investigate CPTO for the alternative TTO procedure. Our findings concerning procedural invariance are rather supportive for the TTO procedure. We find no violations of procedural invariance except for the shortest gauge duration. The results for CPTO are more troublesome: TTO scores depend on gauge duration, reinforcing the evidence reported when using the conventional procedure.

Show MeSH
Mean unadjusted TTO scores (including 95% confidence intervals). Results generated by the conventional procedure are abbreviated by “Con”; those from the alternative procedure by “Alt”. The numbers indicate the corresponding gauge durations
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Fig1: Mean unadjusted TTO scores (including 95% confidence intervals). Results generated by the conventional procedure are abbreviated by “Con”; those from the alternative procedure by “Alt”. The numbers indicate the corresponding gauge durations

Mentions: Figures 1 and 2 show the means and 95% confidence intervals of the unadjusted and adjusted TTO scores, respectively, for all gauge durations and for both the conventional and the alternative procedure. These results indicate, first, that TTO scores are similar for both procedures and, second, that there is a positive correlation between gauge duration and TTO scores.Fig. 1


The way that you do it? An elaborate test of procedural invariance of TTO, using a choice-based design.

Attema AE, Brouwer WB - Eur J Health Econ (2011)

Mean unadjusted TTO scores (including 95% confidence intervals). Results generated by the conventional procedure are abbreviated by “Con”; those from the alternative procedure by “Alt”. The numbers indicate the corresponding gauge durations
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375425&req=5

Fig1: Mean unadjusted TTO scores (including 95% confidence intervals). Results generated by the conventional procedure are abbreviated by “Con”; those from the alternative procedure by “Alt”. The numbers indicate the corresponding gauge durations
Mentions: Figures 1 and 2 show the means and 95% confidence intervals of the unadjusted and adjusted TTO scores, respectively, for all gauge durations and for both the conventional and the alternative procedure. These results indicate, first, that TTO scores are similar for both procedures and, second, that there is a positive correlation between gauge duration and TTO scores.Fig. 1

Bottom Line: An important problem with this method is that results have been found to be responsive to the procedure used to elicit preferences.We find no violations of procedural invariance except for the shortest gauge duration.The results for CPTO are more troublesome: TTO scores depend on gauge duration, reinforcing the evidence reported when using the conventional procedure.

View Article: PubMed Central - PubMed

Affiliation: iBMG/iMTA, Erasmus University, PO Box 1738, 3000, DR, Rotterdam, The Netherlands. attema@bmg.eur.nl

ABSTRACT
The time tradeoff (TTO) method is often used to derive Quality-Adjusted Life Year health state valuations. An important problem with this method is that results have been found to be responsive to the procedure used to elicit preferences. In particular, fixing the duration in the health state to be valued and inferring the duration in full health that renders an individual indifferent, causes valuations to be higher than when the duration in full health is fixed and the duration in the health state to be valued is elicited. This paper presents a new test of procedural invariance for a broad range of time horizons, while using a choice-based design and adjusting for discounting. As one of the known problems with the conventional procedure is the violation of constant proportional tradeoffs (CPTO), we also investigate CPTO for the alternative TTO procedure. Our findings concerning procedural invariance are rather supportive for the TTO procedure. We find no violations of procedural invariance except for the shortest gauge duration. The results for CPTO are more troublesome: TTO scores depend on gauge duration, reinforcing the evidence reported when using the conventional procedure.

Show MeSH