Head-to-head comparison of health-state values derived by a probabilistic choice model and scores on a visual analogue scale.
BACKGROUND
Health states were quantified based on discrete choice (DC) modeling and visual analogue scale (VAS) values using the five-level version of the EQ-5D (EQ-5D-5L). The aim of this study was to determine the extent of the relationship between DC derived values (indirect method) and VAS values (direct method).


METHODS
Data were collected in Canada, the United Kingdom, the Netherlands, and the United States. Respondents were asked to perform paired comparisons between two EQ-5D-5L health states for DC. In total, 400 different EQ-5D-5L states were included. After each DC task, respondents were prompted to score the two states one after another on a VAS. Intraclass correlation coefficients were calculated between DC and VAS values and illuminating graphs were designed.


RESULTS
Approximately 400 respondents participated from each country. High similarity [individual intraclass correlation coefficients (ICC) >0.85] of DC and moderate correspondence of VAS values were observed for the four countries. Cross-country comparison of DC values shows a nonlinear relationship to the VAS values.


CONCLUSIONS
EQ-5D-5L derived DC and VAS values show a close but nonlinear relationship. Given the obvious biases associated with the VAS, DC methods based on ordinal responses may be a better alternative.
Department of Epidemiology, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands. p.f.m.krabbe@umcg.nl.
Paul F M
http://orcid.org/0000-0001-6042-1243
PFM
Krabbe
EuroQol Research Foundation, Marten Meesweg 107, 3068 AV, Rotterdam, The Netherlands.
Elly A
EA
Stolk
Office of Health Economics, 105 Victoria Street, London, SW1E 6QT, UK.
Nancy J
NJ
Devlin
Department of Clinical Epidemiology and Biostatistics, H306 Martha Wing, St. Joseph's Healthcare Hamilton, McMaster University, 50 Charlton Avenue East Hamilton, Ontario, L8N 4A6, Canada.
Feng
F
Xie
Faculty of Mathematics and Natural Sciences, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 19713 AV Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands.
Elise H
EH
Quik
Outcomes and Policy College of Pharmacy, Department of Pharmacy Systems, University of Illinois at Chicago, 833 South Wood St, MC 886, Chicago, IL, 60612, USA.
A Simon
AS
Pickard
D002170:Canada; D003657:Decision Making; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D009426:Netherlands; D011788:Quality of Life; D011795:Surveys and Questionnaires; D006113:United Kingdom; D064232:Visual Analog Scale
Discrete choice model; EQ-5D; Health states; Valuation methods; Visual analogue scale