# EQ-5D

EQ-5D is a popular health related quality of life instrument used in the clinical and economic evaluation of health care. Developed by the EuroQol group, the instrument consists of two components: health state description and evaluation.

For the description component a subject self-rates their health in terms of five dimensions; mobility, self-care, usual activities, pain/discomfort, and anxiety/depression using either a three-level (EQ-5D-3L and EQ-5D-Y) or a five-level (EQ-5D-5L) scale.

The evaluation component requires a patient to record their overall health status using a visual analogue scale (EQ-VAS).

Following assessment the scores from the descriptive component can be reported as a five digit number ranging from 11111 (full health) to 33333/55555 (worst health). A number of methods exist for analysing these five digit profiles. However, frequently they are converted to a single utility index using country specific value sets, which can be used in the clinical and economic evaluation of health care as well as in population health surveys.

The eq5d package provides methods for the cross-sectional and longitudinal analysis of EQ-5D profiles and also the calculation of utility index scores from a subject’s dimension scores. Additionally, a Shiny app is included to enable the calculation, visualisation and automated statistical analysis of multiple EQ-5D index values via a web browser using EQ-5D dimension scores stored in CSV or Excel files.

Value sets for EQ-5D-3L are available for many countries and have been produced using the time trade-off (TTO) valuation technique or the visual analogue scale (VAS) valuation technique. Some countries have TTO and VAS value sets for EQ-5D-3L. Additionally, EQ-5D-3L “reverse crosswalk” value sets published on the EuroQol website that enable EQ-5D-3L data to be mapped to EQ-5D-5L value sets are included.

For EQ-5D-5L, a standardised valuation study protocol (EQ-VT) was developed by the EuroQol group based on the composite time trade-off (cTTO) valuation technique supplemented by a discrete choice experiment (DCE). The EuroQol group recommends users to use a standard value set where available.

The EQ-5D-5L “crosswalk” value sets published by van Hout et al as well as that for Russia are also included. The crosswalk value sets enable index values to be calculated for EQ-5D-5L data where no value set is available by mapping between the EQ-5D-5L and EQ-5D-3L descriptive systems.

The recently published age and sex conditional based mapping data by the NICE Decision Support Unit are also now part of the package. These enable age-sex based EQ-5D-3L to EQ-5D-5L and EQ-5D-5L to EQ-5D-3L mappings from dimensions and exact or approximate utility index scores.

Additional information on EQ-5D can be found on the EuroQol website as well as in Szende et al (2007) and Szende et al (2014). Advice on choosing a value set can also be found on the EuroQol website.

## Installation

You can install the released version of eq5d from CRAN with:

And the development version from GitHub with:

## Analysis of EQ-5D Profiles

A number of methods have been published that enable the analysis of EQ-5D profiles, most recently in the open access book Methods for Analysing and Reporting EQ-5D Data by Devlin, Janssen and Parkin. The eq5d package includes R implentations of some of the methods from this book and from other sources that may be of use in analysing EQ-5D data.

### Cumulative frequency analysis

The eq5dcf function calculates the frequency, percentage, cumulative frequency and cumulative percentage for each five digit profile in an EQ-5D dataset. Either a vector of five digit profiles or a data.frame of indiviual dimensions can be passed to this function in order to summarise data in this way.

### Summarising the Severity of EQ-5D Profiles

The eq5d package includes methods for summarising the severity of EQ-5D health state. The Level Sum Score (LSS) treats each dimension’s level as a number rather than a category. Each number is added up to produce a score between 5 and 15 for EQ-5D-3L and 5 and 25 for EQ-5D-5L.

The Level Frequency Score (LFS) is an alternative method of summarising profile data developed by Oppe and de Charro. Here the frequency of the levels for each health state are characterised. As described in Devlin, Janssen and Parkin’s book, the full health profile 11111 for EQ-5D-5L has 5, 1 s, no level 2, 3, 4 and 5s, so the LFS is 50000; the health profile 55555 is 00005; profiles such as 31524 and 53412 would be 11111.

### Paretian Classification of Health Change

The Paretian Classification of Health Change (PCHC) was developed by Devlin et al in 2010 and is used to compare changes in individuals over time. PCHC classifies the change in an individual’s health state as better (improvement in at least one dimension), worse (a deterioration in at least one dimension), mixed (improvements and deteriorations in dimensions) or there being no change in the health state. Those classified in the No change group with the 11111 health state can be separated into their own “No problems” group. PCHC can be calculated using the pchc function.

#use first 50 entries of each group as pre/post
pre <- data[data$Group=="Group1",][1:50,] post <- data[data$Group=="Group2",][1:50,]

#run pchc function on data.frames

#Show no change, improve, worse, mixed without totals
res1 <- pchc(pre, post, version="3L", no.problems=FALSE, totals=FALSE)
res1
#>              Number Percent
#> No change         5      10
#> Improve          32      64
#> Worsen           10      20
#> Mixed change      3       6

#Show totals, but not those with no problems
res2 <- pchc(pre, post, version="3L", no.problems=FALSE, totals=TRUE)
res2
#>              Number Percent
#> No change         5      10
#> Improve          32      64
#> Worsen           10      20
#> Mixed change      3       6
#> Total            50     100

#Show totals and no problems for each dimension
res3 <- pchc(pre, post, version="3L", no.problems=TRUE, totals=TRUE, by.dimension=TRUE)
res3
#> $MO #> Number Percent #> No change 16 57.1 #> Improve 11 39.3 #> Worsen 1 3.6 #> Total with problems 28 56.0 #> No problems 22 44.0 #> #>$SC
#>                     Number Percent
#> No change               10    37.0
#> Improve                 14    51.9
#> Worsen                   3    11.1
#> Total with problems     27    54.0
#> No problems             23    46.0
#>
#> $UA #> Number Percent #> No change 10 25 #> Improve 26 65 #> Worsen 4 10 #> Total with problems 40 80 #> No problems 10 20 #> #>$PD
#>                     Number Percent
#> No change               27    57.4
#> Improve                 19    40.4
#> Worsen                   1     2.1
#> Total with problems     47    94.0
#> No problems              3     6.0
#>
#>                     Number Percent
#> No change                7    30.4
#> Improve                  9    39.1
#> Worsen                   7    30.4
#> Total with problems     23    46.0
#> No problems             27    54.0

## Helper functions

Helper functions are included, which may be useful in the processing of EQ-5D data. getHealthStates returns a vector of all possible five digit health states for a specified EQ-5D version. getDimensionsFromHealthStates splits a vector of five digit health states into a data.frame of their individual components and getHealthStatesFromDimensions combines indiviual dimensions in a data.frame into five digit health states.

## Example data

Example data is included with the package and can be accessed using the system.file function.

## Shiny web interface

The calculation (and visualisation) of multiple EQ-5D indices can also be performed by upload of a CSV or Excel file using the packaged Shiny app. This requires the shiny, DT, FSA, ggplot2, ggiraph, ggiraphExtra, mime, PMCMRplus, readxl, shinycssloaders and shinyWidgets packages. Ideally the CSV/Excel headers should be the same as the names of the vector passed to the eq5d function i.e. MO, SC, UA, PD and AD or the column name “State” if using the five digit format. However, a modal dialog will prompt the user to select the appropriate columns if the defaults can not be found.

The app is launched using the shiny_eq5d function.

Alternatively, it can be accessed without installing R/Shiny/eq5d by visiting shinyapps.io.