Economics at your fingertips  

Differential item functioning in the EQ-5D: An exploratory analysis using anchoring vignettes

Rachel Knott (), Paula Lorgelly, Nicole Black and Bruce Hollingsworth ()

Health, Econometrics and Data Group (HEDG) Working Papers from HEDG, c/o Department of Economics, University of York

Abstract: Inter-group comparisons using the EQ-5D, or any self-reported measure of health, rely on the measure being an accurate reflection of the true health of the groups or individuals concerned. However, responses to questions on subjective scales, such as those used in the EQ-5D, will be inaccurate if groups of individuals systematically differ in their use of the response categories, a phenomenon known as differential item functioning(DIF). This paper reports on an exploratory analysis involving the use of anchoring vignettes to identify differential item functioning (DIF) in the EQ-5D-5L. We demonstrate that using vignettes to appropriately identify DIF in EQ-5D reporting is possible, at least in certain age groups. We find that the EQ-5D is indeed subject to DIF, and that failure to account for DIF can lead to conclusions that are misleading when using the instrument to compare health or quality of life across heterogeneous groups. For instance, when adjusting for DIF in a sample aged 55-65 years, we found that differences between the highest and lowest education groups doubled in value afteradjusting for DIF, and increased from quantities that would not have had relevance in a clinical settings to ones that would (based on a suggested minimally important difference). Thus, our research provides evidence that the EQ-5D should be used with caution when comparing health or quality of life across heterogeneous groups. We also provide several important insights in terms of the identifying assumptions of response consistency and vignette equivalence.

Keywords: differential item functioning; anchoring vignettes; EQ-5D; response consistency; vignette equivalence (search for similar items in EconPapers)
JEL-codes: I10 C19 C49 (search for similar items in EconPapers)
Date: 2016-08
References: View references in EconPapers View complete reference list from CitEc
Citations: Track citations by RSS feed

Downloads: (external link) Main text (application/pdf)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link:

Access Statistics for this paper

More papers in Health, Econometrics and Data Group (HEDG) Working Papers from HEDG, c/o Department of Economics, University of York HEDG/HERC, Department of Economics and Related Studies, University of York, York, YO10 5DD, United Kingdom. Contact information at EDIRC.
Bibliographic data for series maintained by Jane Rawlings ().

Page updated 2019-11-10
Handle: RePEc:yor:hectdg:16/14