Paul Kind & Richard Brooks 
EQ-5D concepts and methods: 
a developmental history

Science today makes progress through the imaginative harvesting of knowledge g- erated by the many, rather than as the result of the isolated endeavours of the lone researcher. Innovations in the physical sciences from the development of nuclear te- nologies to the laser, have involved research teams working collectively. Collabo- tion is the rule rather than the exception. In the social sciences this model is all but reversed. Here it is not uncommon to encounter the solitary enthusiast, relishing an independence of spirit and pursuing their own private research agenda. All the more surprising then that a group of researchers from several different disciplines, should have come together in the late 1980s with nothing more substantial on the agenda than that they share their thoughts on the topic of measuring the value of health, or more specifically, on the way that the value of health might vary across different countries. Few scientific enterprises can have begun as cautiously or uncertainly. Few can have developed a cohesion and dynamism that lasted decades and continues to drive ahead after long years of scientific endeavour. Such is the good fortune that befell those of us who came together to form what was later to be known as the Euro- Qol Group. The Group’s creation is principally due to the shared professional asso- ation of its members with one man, an economist by training and a visionary academic by inclination and temperament – Alan Williams.

Table of Content

The Euro Qol Instrument.- The descriptive system of the Euro Qol Instrument.- The number of levels in the descriptive system.- First steps to assessing semantic equivalence of the Euro Qol Instrument: Results of a questionnaire survey to members of the Euro Qol Group.- Comparing general health related quality of life (HRQo L) questionnaires; Euro Qol, Sickness Impact Profile and Rosser Index.- Influence of self-rated health and related variables on Euro Qol-valuation of health states in a Spanish population.- Observations on one hundred students filling in the Euro Qol questionnaire.- Eliciting Euro Qol descriptive data and utility scale values from inpatients.- Test-retest reliability of health state valuations collected with the Euro Qol questionnaire.- Hypothetical valuations of health states versus patients’ self-ratings.- Inconsistency and health state valuations.- Issues in the harmonisation of valuation and modeling.- Estimating a parametric relation between health description and health valuation using the Euro Qol Instrument.- Some considerations concerning negative values for EQ-5D health states.- Health states considered worse than ‘being dead’.- The effect of duration on the values given to the Euro Qol states.- Applying paired comparisons models to EQ-5D valuations – deriving TTO utilities from ordinal preference data.- The use and usefulness of the Euro Qol EQ-5D: Preliminary results from an international survey.- Not a quick fix.- Postscript.