EQ-5D

EQ-5D is a standardised instrument for use as a measure of health outcome. Applicable to a wide range of health conditions and treatments, it provides a simple descriptive profile and a single index value for health status. EQ-5D was originally designed to complement other instruments but is now increasingly used as a 'stand alone' measure.

An EQ-5D health state (or profile) is a set of observations about a person defined by a descriptive system. 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.

EQ-5D was established and subsequently developed by the EuroQol Group, established in 1987. The aim of the group is to test the feasibility of jointly developing a standardized non disease specific instrument for describing and valuing health-related quality of life.

As a matter of fact, EQ-5D is becoming popular and one day may be replace the SF-36 as the most popular generalized health-related quality of life instrument. The main advantage of EQ-5D may be:

• Preference-based and suitable for cost-utility analysis
• EQ-5D value sets can be easily converted to the QALY which is the denominator in cost-utility analysis.
• Less questions and easy to implement within short time

In one of my studies, SF-36 were performed as a quality of life measure. However, in order to perform the cost-utility analysis, these SF-36 scores have to be converted into something similar to EQ-5D - SF-6D . There is also other discussions about the mapping of SF-36 to EQ-5D. QualityMetric, the company for developing SF-36, is also providing the mapping for SF-6D.

However, the analysis of EQ-5D is not as easy as the questions presented in the instrument. According to a book titled "EQ-5D value sets: inventory, comparative review and user guide" (see UNC catalog), two terms seem to be important, but I may need to do a complete study using EQ-5D to figure out how to use these value sets.

• Time Trade-off (TTO) value sets
• Visual Aalogue Scale value sets