Choosing a value set
The responses to the five EQ-5D dimensions (i.e. an EQ-5D health state or profile) can be converted into a single number called an index value. The index value reflects how good or bad the health state is according to the preferences of the general population of a country. The collection of index values for all possible EQ-5D states is called a value set. Value sets are currently available for the EQ-5D-3L and EQ-5D-5L for different countries. Several valuation techniques have been used to generate these value sets: time trade-off (TTO), visual analogue scale (VAS), and more recently, discrete choice experiments (DCE).
The starting point when selecting a value set is the anticipated use of the EQ-5D data. Once this decision has been made, a set of weights that represent the general population’s preferences might be the ideal system of choice, but such a system might not be available for your country. The following flowchart and considerations may help you to choose the most appropriate value set.
For economic studies where cost-utility analysis is anticipated, most health economists would recommend a TTO-based value set. If a TTO-based value set is not available for your country, you can select a TTO value set for a country that most closely approximates yours. Alternatively, you can use a VAS-based value set if that is available for your country.
For economic studies where cost-utility analysis is not anticipated, either a VAS value set or a TTO value set can be used. If a value set is not available for your country, you can select a value set for a country that most closely approximates yours.
For non-economic studies where index values are to be used, either a VAS value set or a TTO value set can be used. If a value set is not available for your country, you can select a value set for a country that most closely approximates yours. Depending on the type and purpose of a non-economic study, the use of a VAS value set could be more appropriate than a TTOvalue set.
Crosswalk value sets for the EQ-5D-5L
If an EQ-5D-5L value set is not available for your country, then a so-called “crosswalk” value set can be used. A crosswalk value set is one that has been created for the EQ-5D-3L and then adapted to fit the EQ-5D-5L descriptive system.
The crosswalk value sets were created by the EuroQol Group as an interim solution for use until national EQ-5D-5L value sets are available. Crosswalk value sets are based on a study that administered both the EQ-5D-3L and the EQ-5D-5L in a sample of 3691 patients with different diseases and from different countries. More information on the crosswalk methodology can be found here and here.
If you would like to use a crosswalk value set, please contact the EuroQol Office.