Probably the dominant quality of life measure, distributed by Euroqol and free for non-commercial use if you register with them. The EQ-5D-5L has five questions each with a five level score of severity of problems and then it has a visual analogue scale (VAS) arranged vertically on the second page (in the paper version). The VAS is marked off from 0 to 100 in 5 point increments but little marks show the integer levels. The VAS is scored by putting a cross on the scale and translated into an integer between 0 and 100. The five initial questions cover:

  • Mobility
  • Self-care
  • Usual activities
  • Pain/discomfort
  • Anxiety/Depression

Each of the initial questions has five options, those for anxiety/depression are:
I am not anxious or depressed
I am slightly anxious or depressed
I am moderately anxious or depressed
I am severely anxious or depressed
I am extremely anxious or depressed

This six item set of data can actually be used in three different ways:

  • The scores on the five individual questions can be used as they are as when the names are often shortened slightly to: measures of mobility, self-care, activity, pain and anxiety
  • The VAS scores can also be used as they stand.
  • Finally the item scores can be converted to a “utility value”. In this process, each level is coded 1 to 5 (in the order they appear) and those codes are converted to a “health state”, also, sensibly to my mind, called “profiles” e.g. 12345. Each number in the profile is the response to the corresponding question in the same order in which they occur. Those health states are then converted to a utility value or “index value” by looking them up against national mappings created by one of a Euroqol set of procedures including direct subjective ratings (using a VAS but not the one in the measure I think) or discrete choice or time trade off methods. These utility or index values can be fed into health economic QALY (Quality Adjusted Life Year) evaluations.

Details #

There are very comprehensive and readable details on the Euroqol pages for the EQ-5D-5L so if you are thinking of using the EQ-5D-5L you should definitely go there or if you don’t understand something in a report using the measure that’s the next place to go from here. (My own experience is that work using the EQ-5D-5L often seems to me to be poorly explained and not to live up to the clear guidelines about reporting scores from the measure in the Euroqol pages.)

However, it may be worth me unpacking the health profile/index mapping a bit more. I was helped in this by using the excellent eq5d package for R. Suppose I answer “1” to all five items then I have a profile 11111 and that maps to a utility/index value of 1 (so in QALY terms if I maintain that state for a year I have had a full “Quality Adjusted Life Year” of 1 year. However, if I have a profile of 12345 using the UK (actually England in the lookup tables) mapping then that has a utility/index value of .3 and a year in that state in QALY terms was only .3 of a full quality year. If I had the worst profile of 5555 the UK mapping is to -.3 which illustrates the important idea behind QALYs: that some states are considered so bad as negative years.

Interestingly, if I put my country of semigration France in instead of England I get values of 1, .4 and -.5 instead 1, .3 and -.3. There are mappings for many different countries.

Try also #

Discrete choice experiments
Health economics
Quality of life
Visual Analogue Scales (VAS)

Chapters #

Mentioned in Chapters 2, 4 and 6.

Online resources #

The excellent eq5d package for R.

Dates #

First created 27.iii.24, tweaked links 30.iii.24.

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