Valuation of EQ-5D
An EQ-5D health state (or profile) is a set of observations about a person defined by the descriptive system on page 2. An EQ-5D health state may be converted to a single summary index by applying a formula that essentially attaches weights to each of the levels in each dimension. This formula is based on the valuation of EQ-5D health states from general population samples.
Over the past few years, the EuroQol Group has been engaged in several research projects exploring this conversion of a health state into a single index value. Value sets are commonly produced by valuing a selection of EQ-5D states and, using econometric techniques, to extrapolate over the full set of states. A subset of health states for valuation was decided by the Group in 1990. For various reasons however, valuation studies have not always adhered to the standard approach.
The standardized extended version of EQ-5D was designed for the collection of health state values using a VAS rating scale - a vertical 20 cm visual analogue scale with the end points labelled best imaginable health state at the top and worst imaginable health state at the bottom having numeric values of 100 and 0 respectively.
The EQ-5D valuation questionnaire is only distributed in instances where researchers specifically wish to elicit valuations of health. It should not be used in routine clinical or economic studies or population health surveys.
Value sets have been elicited from respondents using the EQ-5D VAS technique and the time trade-off method (TTO). A recent EU funded project has provided support to harmonize and integrate the results of some of the European projects resulting in a European VAS value set.
If you wish to carry out a valuation study using EQ-5D you are required to contact the EuroQol Executive Director for permission. The EuroQol Group has created a Valuation Working Group which has produced new protocols for VAS and TTO valuation methods as well as exploring newer methods like DCE. It is important that any new research benefits from the EuroQol Group's experience.