EQ-5D data are often summarised by an EQ-5D index, whose distribution for its original version, the EQ-5D-3L, often shows two distinct groups in patient populations, arising from both the distribution of ill health and how the index is constructed. To date, there is little evidence about the distribution of the EQ-5D-5L index. This project aims to:
- explore whether or not the EQ-5D-5L index distribution also demonstrates this two-group distribution
- test the extent to which clustering of EQ-5D-5L profile data drives any observed clustering of the EQ-5D-5L index, and the extent to which clusters result from the characteristics of the value sets used to create the index;
- discuss the implications of our results for statistical analysis of EQ-5D-5L index data.
The results highlight the importance of undertaking careful exploratory data analysis for health related quality of life measures such as the EQ-5D, to ensure that statistical testing takes account of clustering and other features of the data distribution.