(EQ-5D + VAS) x Rasch = HRQoL Measure

The EQ-5D questionnaire and the EQ Visual Analogue Scale (EQ-VAS) were developed by the EuroQol Group for deriving the preference-weighted single indices used for economics studies involving tradeoffs. This study investigates the extent to which the five EQ-5D items and the VAS together form a valid measure of Health Related Quality of Life (HRQoL) in a U.S. representative sample diagnosed with the most prevalent chronic health conditions.

The EQ-5D-3L has 5 items classifying health in terms of mobility (MO), self-care (SC), usual activities (UA), pain/discomfort (PD) and anxiety/depression (AD), with the 3 response category coding gave lower scores for healthier respondents. The original 101 VAS categories were collapsed to form a 9-category item to ensure sufficient frequency of endorsement for each VAS category with coding reversed to be consistent with the EQ-5D.

Respondents extracted from the 2-year panel (2002-03) from the Medical Expenditure Panel Survey (MEPS) 1) were =18 years of age; 2) had complete EQ-5Ds, and 3) reported primary ICD-9-CM for the top 10 most prevalent chronic health conditions (Table 1).

The Rasch rating scale model (RSM) was used to calibrate the responses on the five items and the partial credit model (PCM) for the categorized VAS scores. Fit of the six items to the Rasch model was assessed by using the INFIT mean square (INFIT MNSQ <1.4).

Figures: Gender-related DIF with VAS - 2002, and Disease-related DIF with VAS - 2003. The x-axis shows the EQ-5D items and the y-axis is the DIF measure by DIF grouping. (p<0.01).

Results: There was significant gender-related DIF (p < 0.01) on the EQ 5D "anxiety/depression" mental health item and significant disease-related DIF (p < 0.01) "anxiety/depression" for respondents diagnosed with depression or anxiety, with or without the VAS, in both years. Responses from the VAS consistently fit the Rasch model (INFIT MNSQ < 1.4) over the two time points and across all ten disease groups.

Misfit was shown by the "anxiety/depression" mental health item, esp. with 2002 data; and improved fit in 2003, esp. with the inclusion of VAS. Analyses using a gender-split on the "anxiety/depression" item improved fit to the model among males (in 8 out of 10 first year and 9 out of 10 second year disease groups). When enhanced by the inclusion of the VAS, the EQ-5D descriptive system exhibited satisfactory Rasch measurement qualities and further enhancement was achieved by purging the gender and disease effects.

Results compared across both years revealed the crucial measurement property of invariance for the EQ-5D. The findings suggest that 1) the EQ-5D descriptive system and the EQ-VAS can be combined together to provide an overall measure of HRQoL and, 2) together they might serve as a suitable measurement framework for deriving population preference-weights.

Ning Yan Gu, Pharmerit North America, LLC, Bethesda, Maryland USA

Trevor G. Bond, School of Education, James Cook University, Townsville, Queensland, Australia

Benjamin M. Craig, Health Outcomes and Behaviors, Moffitt Cancer Center, Tampa, Florida USA

Reference: The EuroQol group (1990) "EuroQol a new facility for the measurement of health related quality of life." Health Policy, 16,199-208.

Based on a poster presented at 26th Plenary meeting of the EuroQol Group , Paris, France, September 3rd - 5th, 2009

Gu N.Y., Bond T.G., Craig B.M. (2009) (EQ-5D + VAS) x Rasch = HRQoL Measure, Rasch Measurement Transactions, 2009, 23:3, 1215-1216

Rasch Books and Publications
Invariant Measurement: Using Rasch Models in the Social, Behavioral, and Health Sciences, 2nd Edn. George Engelhard, Jr. & Jue Wang	Applying the Rasch Model (Winsteps, Facets) 4th Ed., Bond, Yan, Heene	Advances in Rasch Analyses in the Human Sciences (Winsteps, Facets) 1st Ed., Boone, Staver	Advances in Applications of Rasch Measurement in Science Education, X. Liu & W. J. Boone	Rasch Analysis in the Human Sciences (Winsteps) Boone, Staver, Yale
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes	Statistical Analyses for Language Testers (Facets), Rita Green	Invariant Measurement with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments (Facets), George Engelhard, Jr. & Stefanie Wind	Aplicação do Modelo de Rasch (Português), de Bond, Trevor G., Fox, Christine M	Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
Exploring Rating Scale Functioning for Survey Research (R, Facets), Stefanie Wind	Rasch Measurement: Applications, Khine	Winsteps Tutorials - free Facets Tutorials - free	Many-Facet Rasch Measurement (Facets) - free, J.M. Linacre	Fairness, Justice and Language Assessment (Winsteps, Facets), McNamara, Knoch, Fan
Other Rasch-Related Resources: Rasch Measurement YouTube Channel
Rasch Measurement Transactions & Rasch Measurement research papers - free	An Introduction to the Rasch Model with Examples in R (eRm, etc.), Debelak, Strobl, Zeigenfuse	Rasch Measurement Theory Analysis in R, Wind, Hua	Applying the Rasch Model in Social Sciences Using R, Lamprianou	El modelo métrico de Rasch: Fundamentación, implementación e interpretación de la medida en ciencias sociales (Spanish Edition), Manuel González-Montesinos M.
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar	Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch	Rasch Models for Measurement, David Andrich	Constructing Measures, Mark Wilson	Best Test Design - free, Wright & Stone Rating Scale Analysis - free, Wright & Masters
Virtual Standard Setting: Setting Cut Scores, Charalambos Kollias	Diseño de Mejores Pruebas - free, Spanish Best Test Design	A Course in Rasch Measurement Theory, Andrich, Marais	Rasch Models in Health, Christensen, Kreiner, Mesba	Multivariate and Mixture Distribution Rasch Models, von Davier, Carstensen

Forum

Rasch Measurement Forum to discuss any Rasch-related topic

Go to Top of Page
Go to index of all Rasch Measurement Transactions
AERA members: Join the Rasch Measurement SIG and receive the printed version of RMT
Some back issues of RMT are available as bound volumes
Subscribe to Journal of Applied Measurement

Go to Institute for Objective Measurement Home Page. The Rasch Measurement SIG (AERA) thanks the Institute for Objective Measurement for inviting the publication of Rasch Measurement Transactions on the Institute's website, www.rasch.org.

The URL of this page is www.rasch.org/rmt/rmt233a.htm

Website: www.rasch.org/rmt/contents.htm