SHEDDING NEW LIGHT ONTO THE CEILING AND FLOOR? A QUANTILE REGRESSION APPROACH TO COMPARE EQ-5D AND SF-6D RESPONSES
Janelle Seymour, Paul McNamee, Anthony Scott, Michela Tinelli
HEALTH ECONOMICS | WILEY | Published : 2010
An important issue in the measurement of health status concerns the extent to which an instrument displays lack of sensitivity to changes in health status at the extremes of the distribution, known as floor and ceiling effects. Previous studies use relatively simple methods that focus on the mean of the distribution to examine these effects. The aim of this paper is to determine whether quantile regression using longitudinal data improves our understanding of the relationship between quality of life instruments. The study uses EQ-5D and SF-36 (converted to SF-6D values) instruments with both baseline and follow-up data. Relative to ordinary least least-squares (OLS), a first difference model..View full abstract
Awarded by Medical Research Council
Awarded by Chief Scientist Office
The authors would like to thank Richard Osborne for his helpful comments and suggestions. We would also like to thank Professor Christine Bond (principle investigator on the Medman trial) for her involvement in the study and her comments on the paper. The Medman study was funded by the Department of Health for England and Wales and managed by a collaboration of the National Pharmaceutical Association, the Royal Pharmaceutical Society of Great Britain, the Company Chemist Association and the Co-operative Pharmacy Technical Panel, led by the Pharmaceutical Services Negotiating Committee. The Health Economics Research Unit (HERU), University of Aberdeen is funded by the Chief Scientist Office of the Scottish Executive. The research in this paper was undertaken while the author JS was a research fellow at HERU. We are also grateful to the Institute of Applied Health Sciences, University of Aberdeen, for funding support. The views expressed in this paper are those of the authors and not the funders. There are no financial or other conflicts of interest concerning this work and it has not been published elsewhere.