Psychometric properties of the EQ-5D-3L in South Australia: a multi-method non-preference-based validation study

Abstract

Objective

Although HRQoL tools such as the EQ-5D-3L are significant in determining health status, these measures have not been validated in general populations in Australia. This study aims to psychometrically validate the EQ-5D-3L in a large population sample in Australia for the first time.

Methods

The EQ-5D-3L was included in the Dental Care and Oral Health study (DCOHS), conducted in a South Australian population sample. The participants were 23–91 years old, and 44.1% were male. The EQ-5D-3L was responded to on a three-point rating scale (“none”/“no”, “some” and “extremely”/“unable”/“confined”). We employed the area under the receiver operating characteristic curve (AUROC) to evaluate whether the EQ-5D-3L total score could identify participants with diagnosed diseases and mental health disorders. Psychometric validation of the EQ-5D-3L investigated dimensionality with Exploratory Graph Analysis, model fit, floor/ceiling effects and criterion validity.

Results

The EQ-5D-3L comprised two dimensions, Activities and Symptoms. According to Root Mean Squared Error of Approximation (RMSEA) (<.05) and Comparative Fit Index (CFI) (>.950), the 2-dimensional structure showed excellent model fit with good reliability for the Activities subscale (Ωc = 0.80–95% CI [0.77, 0.83]), and poor reliability for the Symptom subscale (Ωc = 0.56–95% CI [0.53, 0.58]). The EQ-5D-3L showed adequate reliability (Ωc = 0.70–95% CI [0.67, 0.72]). The EQ-5D-3L showed good discrimination for diagnosed diseases (ranging from 64.3% to 86.3%). Floor/ceiling effects were observed across all items. The EQ-5D-3L total score discriminated between respondents who were experiencing health conditions (e.g. cancer, cardiovascular disease, stroke) from healthy individuals.

Discussion

Despite the ceiling effects, the EQ-5D-3L displayed good psychometric properties as an HRQoL measure and discriminated between health states in the general South Australian population. Further research should investigate the psychometric properties of the EQ-5D-5L in South Australia and whether an increased number of response categories can mitigate the observed ceiling effects.

Keywords:

• Health-related quality of life
• quality-adjusted life-years
• psychometrics
• health status

Transparency

Declaration of funding

This study was funded by National Health and Medical Research Council, Grant/Award Number: 1031310. The funding body was not involved in the design of the study, data collection, analysis, interpretation of data, and writing of the manuscript.

Declaration of financial/other relationships

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Author contributions

MZ and PHRS conceived the idea. MZ developed the study and wrote the manuscript, and SS and PHRS participated in completing the manuscript. PHRS conducted the psychometric analysis and validation. DB and LJ supervised the development of work. DH, DB and LJ critically reviewed the manuscript and provided intellectual contribution to the analysis. All authors read and approved the final version of the manuscript.

Acknowledgements

Not applicable/No assistance in the preparation of this article is to be declared.

Data availability statement

The dataset that generated and/or analysed during this study are available on reasonable request from the corresponding author. The dataset is not publicly available due to privacy or ethical restrictions.

Ethics approval

Ethics approval was obtained from the University of Adelaide Human Research Ethics Committee (H-288-2011). The participants' information for this study remained confidential. Also, the participant's identity was protected through the reporting of results in aggregate form.

Participating in this study was voluntary and confidential, and participants gave consent for publication through the questionnaire.