INTERNATIONAL VALUATION SET FOR EQ-5D HEALTH STATES

Author(s)

Benjamin M. Craig, PhD, Assistant Professor of Oncological Sciences and Economics1, Jan J. Busschbach, PhD, Senior Research Associate2, Joshua Salomon, PhD, Assistant Professor31Moffitt Cancer Center, Tampa, FL, USA; 2 Erasmus Medical Center, Rotterdam, Netherlands; 3 Harvard University, Boston, MA, USA

Objective: Health states defined by classification systems like the EQ-5D can be valued using techniques that aim to elicit cardinal measures directly, such as the time trade-off (TTO) and visual analogue scale (VAS), but also by ranking the health states. In this study, we estimate international value sets for the 243 EQ-5D states based on rank, TTO and VAS responses and test their equivalence. Methods: We estimated the coefficients of a conditional logit and a linear probability model of rank responses as well as the coefficients of two linear models of TTO and VAS responses using pooled data from eight countries: Slovenia, Argentina, Denmark, Japan, Netherlands, Spain, UK and US, which gave us 179,431 responses from 11,483 subjects. The main difference between the two rank models is that one models utility in ln(odds), as suggested by McFadden, and the second in probability. The regression specifications have previous models estimated in the United States and United Kingdom nested within its framework. Furthermore, we compare rescaled predicted values for the 242 EQ-5D states, excluding 11,111, across techniques in terms of correlation and concordance. Results: The non-optimal gap reduces when utilities are linearly modeled in probability instead of log-odds, as suggested by McFadden. The rank-based values are highly correlated with both TTO and VAS values. Compared to the log-odds model, the linear probability model produces rank-based values with greater concordance to TTO/VAS values. Conclusion: In former investigations we tested if ranking in the large pool of data produce values of health states comparable with direct measures as TTO and VAS. In this investigation we provide further evidence by showing convergent validity between TTO/VAS and alternative rank-based models for the whole valuation space. This evidence emphasizes the promise of a valuation technique that incorporates ordinal responses. Overall, rank-based values merits closer investigation.

Conference/Value in Health Info

2008-05, ISPOR 2008, Toronto, Ontario, Canada

Value in Health, Vol. 11, No. 3 (May/June 2008)

Code

PMC29

Topic

Methodological & Statistical Research

Topic Subcategory

PRO & Related Methods

Disease

Multiple Diseases

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