Test-retest reliability of health state valuations collected with the EuroQol questionnaire

This study is a contribution by the Dutch participants to the research programme of the EuroQol Group. This collaborative group of researchers engaged in outcome measurement is working towards the development of a standardized, non-disease-specific instrument for describing and particularly valuing health-related quality of life. The present article analyses the test-retest reliability of the valuations collected with the EuroQol questionnaire in a population survey (n=208). The choice of the appropriate method for test-retest analysis is discussed and the results of several approaches with the EuroQol data are shown. Generalizability Theory is proposed as the most suitable method. This method is the most comprehensive, giving distinct information about the relative contributions of different sources of variance. The EuroQol valuations appear to have good test-retest reliability.