title: The effect of adding a cognitive dimension to the EuroQol multiattribute health-status classification system.
abstract: A methodological study was conducted to examine the effect of extending a frequently used simple multiattribute health-status classification system by adding a cognitive dimension. The EQ-5D questionnaire is a generic instrument to value health, developed by the EuroQol Group. The EQ-5D defines health according to five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. We defined 18 different health states according to the standard EQ-5D classification. A second set of health states was constructed similar to the first, except for the addition of a cognitive dimension (EQ-5D+C). Valuations of both sets of health states were statistically analyzed to detect the effect of the additional dimension. The cognitive dimension generated systematically different values compared with the standard EQ-5D version, whereas the content validity improved. Both systems evoked equally reliable values. Analyses showed that a simple additive model to predict summary values for health states was not optimal for both systems. Although there is a current lack of consensus regarding the domains that are selected to represent health status, this study has shown the importance of considering the inclusion of a cognitive domain.
authors.affiliation: Department of Public Health, Faculty of Medicine, Erasmus University, Rotterdam, The Netherlands.
authors.forename: P F
authors.initials: PF
authors.lastname: Krabbe
authors.forename: M E
authors.initials: ME
authors.lastname: Stouthard
authors.forename: M L
authors.initials: ML
authors.lastname: Essink-Bot
authors.forename: G J
authors.initials: GJ
authors.lastname: Bonsel
mesh_terms: D000203:Activities of Daily Living / Q000145:classification; D000328:Adult; D001007:Anxiety / Q000145:classification; D003071:Cognition / Q000145:classification*; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D010146:Pain / Q000145:classification; D015203:Reproducibility of Results; D012107:Research Design; D011795:Surveys and Questionnaires