a1 University Hospital Leiden
a2 Erasmus University Rotterdam
a3 University Hospital Leiden
a4 University Hospital Leiden and Academic Medical Centre, Amsterdam
Methods often used for the valuation of health states are the time trade-off (TTO) and the visual analog scale (VAS). The VAS is easier than the TTO and can be self-administered; however it usually leads to lower scores. In the literature a power transformation of group mean VAS scores to TTO scores has been proposed. We were able to replicate this finding of a power function. We found coefficients that were very similar to those from the literature, for 183 cancer patients. The relationship existed independently of disease state and health status.