Using the EuroQol EQ-5D in Swiss Cancer Patients, Which Value Set Should be Applied?
The European Quality of Life–5 Dimensions (EQ-5D) instrument combines questionnaire responses into a single utility estimate using country-specific value sets. Countries without a national value set are advised to select one based on geographic proximity. In the absence of a Swiss value set, we used foreign value sets to gain insights into their appropriateness for use with Swiss cancer patients.
EQ-5D health states and visual analogue scale (VAS) ratings were collected in one German and three Swiss oncology trials. Utilities were calculated based on the United Kingdom (UK), German (GE), French (FR) and European Union (EU) value sets. Resulting differences and Pearson partial correlation coefficients with corresponding VAS ratings were assessed.
In total, 202 Swiss and 154 German patients undergoing cancer treatment completed at least two EQ-5D forms. The mean difference between GE-based and FR-, UK- or EU-based utilities was significantly larger than the differences between the latter. The absolute mean difference between utilities and VAS ratings was highest for GE-based utilities, for Swiss (0.170, 95 % confidence interval [CI] 0.146–0.194) and German patients (0.174, 95 % CI 0.145–0.202). The correlation between GE-based utilities and VAS ratings was the lowest (r = 0.36, 95 % CI 0.33–0.40); the highest was between FR-based utilities and VAS ratings (r = 0.43, 95 % CI 0.39–0.46).
For Switzerland, utility calculations based on the German or French value set would be an obvious choice. Our results suggest that the German value set may not be the most appropriate for use with Swiss cancer patients. The French and EU value sets may be relevant alternatives and improve international comparability.
The authors would like to thank the principal investigators Prof. Dr. med Christoph Rochlitz (SAKK 24/09), Prof. Dr. med Thomas Ruhstaller (SAKK 75/08), Prof. Dr. med Jean-François Dufour (SAKK 77/09) and Dr. med Markus Jörger (CEPAC-TDM) for providing the EQ-5D data for this study.
Source of financial support
This study was funded by the Swiss State Secretariat for Education, Research and Innovation. The Health economic sub-project of the SAKK Trial 75/08 was funded by a grant from the Swiss Cancer Research Foundation.
Conflict of interest
The authors declare no conflicts of interest.
Klazien Matter-Walstra was the main person responsible for planning and conducting the study, performing statistical analyses and writing the manuscript.
Dirk Klingbiel gave statistical support and reviewed the manuscript.
Matthias Schwenkglenks contributed to the planning of the study and interpretation of results, and reviewed the manuscript.
Thomas Szucs, Bernhard Pestalozzi gave support on content and reviewed the manuscript.
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