EQ-5D-5L | FAQs
What does the EQ-5D stand for?
EQ-5D is the name of the instrument and is not an acronym. EQ-5D is the correct term to use in print or verbally.
What is the difference between the EQ-5D-5L descriptive system, the EQ VAS and the EQ-5D index values?
The descriptive system section of the EQ-5D questionnaire produces a 5-digit health state profile that represents the level of reported problems on each of the five dimensions of health, e.g.EQ-5D-5L health state 21143 represents a patient who indicates slight problems on the mobility dimension, no problems on the self-care and usual activities dimensions, severe pain or discomfort and moderate problems on the anxiety/depression dimension. These health states can be converted into a single index value using one of the standard EQ-5D-5L value sets. These value sets reflect the preferences of the general population. In contrast, the EQ VAS scores are self-reported and are therefore not representative of the general population. The EQ VAS self-rating records the respondent’s own assessment of their health status. Furthermore, the EQ VAS scores are anchored on 100 = the best health you can imagine and 0 = the worst health you can imagine, whereas the value sets are anchored on 11111 = 1 (representing full health) and dead = 0 and can therefore be used in QALY calculations.
How are the self-complete, interviewer and proxy EQ-5D versions different?
EQ-5D is designed for self-completion by respondents. However, several other modes of administration are also available.
The interviewer version is convenient when respondents are unable to read or write, or when subject are unable to come to the study site. An interviewer will read the instructions and record the responses.
Proxy EQ-5D versions are available for use when patients are mentally or physically incapable of reporting on their health-related quality of life, for instance because of severe intellectual disability or mental health problems. Two proxy versions are currently available where a caregiver who knows the patient well (for example, a parent, physician or nurse) is asked to complete EQ-5D as follows:
- EQ-5D-5L Proxy version 1: The caregiver (the proxy) is asked to rate the patient’s health-related quality of life in their (the proxy’s) opinion.
- EQ-5D-5L Proxy version 2: The caregiver (the proxy) is asked to rate how he/she (the proxy) thinks the patient would rate his/her own health-related quality of life if the patient were able to communicate it.
Can I use only the five dimensions of the questionnaire, or only the EQ VAS?
Please note that without the prior written consent of the EuroQol Office, you are not permitted to alter, amend or convert the EQ-5D-5L and related proprietary materials.
We do not advise using only part of the questionnaire. EQ-5D-5L is a two-part instrument. If you only use one part, you cannot claim to have used EQ-5D-5L in your publications.
How do I get the EQ-5D in the languages that I need?
To obtain a copy of the instrument, please complete the EQ-5D registration form. During the registration process you can select the countries in which you intend to collect EQ-5D data, the languages that you will need and the mode(s) of administration.
The EuroQol Office will then contact you by e-mail and inform you about the terms and conditions which apply if you decide to use the EQ-5D, including licensing fees (if applicable). Please allow approximately 5 working days to receive this reply.
For what period of time does EQ-5D-5L record health status?
Self-reported health status captured by EQ-5D-5L relates to the respondent’s situation at the time of completion. No attempt is made to summarize the recalled health status over the preceding days or weeks, although EQ-5D-3L has been tested in recall mode. An early decision taken by the EuroQol Group determined that health status measurement ought to apply to the respondent’s immediate situation – hence the focus on ‘your health today’.
Can I change the time frame of the questionnaire?
Without the prior written consent of the EuroQol Office, you are not permitted to alter, amend or convert the EQ-5D-5L and related proprietary materials. This includes changing the time frame.
If you have any plans to conduct a scientific study investigating a modification of EQ-5D please contact the EuroQol Office.
Am I allowed to make changes to the EQ-5D?
Without the prior written consent of the EuroQol Office, you are not permitted to alter, amend or convert the EQ-5D-5L and related proprietary materials.
If you have any plans to conduct a scientific study investigating a modification of EQ-5D please contact the EuroQol Office.
I have seen EQ-5D ‘language’ using 5 numbers (e.g. 12321 or 43251). What does this mean?
The descriptive system section of the EQ-5D questionnaire produces a 5-digit health state profile that represents the level of reported problems on each of the five dimensions of health, e.g. EQ-5D-5L health state 11313 represents a patient who indicates moderate problems on the usual activities and anxiety/depression dimensions and no problems on the remaining dimensions. Please note that this is just a ‘shorthand’ way of describing an EQ-5D health state; the numbers are simply code for the level in each dimension and have no arithmetic properties whatsoever. Therefore, they should not, for example, be added to give an overall score.
Where can I find STATA/SPSS tools for EQ-5D, such as syntax files?
Please contact the EuroQol office.
How can the digital based EQ-5D questionnaires be integrated into a larger set of patient questionnaires?
Typically, EQ-5D is one of several questionnaires that are used in a study. Depending on your situation, you will either be using a system such as REDCap to combine all these questionnaires and collect the data, or you will be working with an eCRF vendor who will take care of this.
Can I combine results from different modes of administration?
In some cases, data may be collected using different approaches within the same study. Three situations are not uncommon:
- data may be collected using a combination of self-complete versions and patient interview versions (e.g. in a study with trauma patients in which some patients can physically complete the questionnaire, but others cannot – though they are capable of responding in an interview);
- data may be collected in some cases using a paper version and in other cases using a digital version of the questionnaire, within the same study;
- data is collected from a combination of proxy-reporters and patients (e.g. in a study with stroke patients, where some patients can respond for themselves and others cannot respond at all, on either the self-complete or the interviewer version).
It is likely to be of interest to aggregate data collected in the same study using different modes of administration and/or from different types of respondent (patient versus proxy). However, this is currently probably only appropriate, at least without further in-study analysis of response patterns, in the case of b), where evidence suggests substantial levels of equivalence in response between electronic and paper versions of PRO instruments (see Muehlhausen et al, 2015). In the case of a) and c), there is insufficient evidence to show that EQ-5D responses collected using self-complete versus interview modes of administration or from proxies versus patients can be aggregated. One study with EQ-5D found that face-to-face and interview administration provided similar results (Chatterji et al, 2017), however, little work has been done in this area and studies with other PRO instruments in the literature have shown that results can differ between the two modes of administration.
Regarding the equivalence of proxy and patient responses, research to date suggests that responses should probably not be directly aggregated, at least without further within-study analysis of responses patterns. Hounsome et al (2011) found that proxy versions had good reliability and validity for use in dementia patients but highlighted that it was important to select appropriate proxies and that different proxies (e.g., family carers, institutional carers, and health-care professionals) provide different ratings for patients’ health. They also noted that there was a lack of association between patient and proxy ratings. In a review of the use of EQ-5D in stroke patients, Oczkowski et al (2010) found that most studies reported that proxy respondents overestimated impairments compared with patient self-reports. Gabbe et al (2012) found that, in trauma patients 12 months after injury, agreement between patient and proxy respondents was substantial for the mobility and self-care items and moderate for the remaining 3 dimensions.
Based on these considerations, in the case of a) and c), we recommend that when different modes of administration are used, a variable indicating mode of administration should be recorded in the data set. Data should always be analysed separately before aggregating, and researchers should report consent rates, data completeness and other potential sources of bias for the different modes of administration.
Muehlhausen W et al. Equivalence of electronic and paper administration of patient-reported outcome measures: a systematic review and meta-analysis of studies conducted between 2007 and 2013. Health Qual Life Outcomes 2015;13:167.
Can I publish our study using EQ-5D?
Yes, you are free to publish your results. If you would like to reproduce the EQ-5D questionnaire in your publication, please contact the EuroQol Office.
How do I refer to the EQ-5D-5L instrument in publications?
When publishing results obtained with the EQ-5D-5L, the following key references can be used:
- The EuroQol Group (1990). EuroQol-a new facility for the measurement of health-related quality of life. Health Policy 16(3):199-208.
- Brooks R (1996). EuroQol: the current state of play. Health Policy 37(1):53-72.
- Rabin, R., & de Charro, F (2001). EQ-5D: a measure of health status from the EuroQol Group. Annals of Medicine 33(5):337-343.
- Herdman M, Gudex C, Lloyd A, Janssen MF, Kind P, Parkin D, Bonsel G, Badia X (2011). Development and preliminary testing of the new five-level version of EQ-5D (EQ-5D-5L). Quality of Life Research 20(10):1727-36.
- Janssen MF, Pickard AS, Golicki D, Gudex C, Niewada M, Scalone L, Swinburn P, Busschbach J (2013). Measurement properties of the EQ-5D-5L compared to the EQ-5D-3L across eight patient groups: a multi-country study. Quality of Life Research 22(7):1717-27.
- Buchholz I, Janssen MF, Kohlmann T, Feng YS (2018). A systematic review of studies comparing the measurement properties of the three-level and five-level versions of the EQ-5D. Pharmacoeconomics 36(6):645-661.
- Janssen MF, Bonsel GJ, Luo N (2018). Is EQ-5D-5L Better Than EQ-5D-3L? A Head-to-Head comparison of descriptive systems and value sets from seven countries. Pharmacoeconomics 36(6):675-697.
Can I use the EQ-5D-5L data in a NICE submission?
Please see this webpage for NICE’s position statement on the use of the EQ-5D-5L (updated November 2018). NICE continues to recommend that:
- Data collected using the EQ-5D-5L and EQ-5D-3L versions may be used for reference-case analyses.
- Prospective clinical studies should continue to use the EQ-5D-5L descriptive version to collect data on quality of life.
- If the EQ-5D-5L measure is used for analyses, scoring should be undertaken using the mapping algorithm by van Hout et al (2012) [the crosswalk tool].
Further information is available on the EuroQol website about how to use the crosswalk tool to map the EQ-5D-5L responses collected in your study to the UK 3L value set.
van Hout B, Janssen MF, Feng YS, Kohlmann T, Busschbach J, Golicki D, Lloyd A, Scalone L, Kind P, Pickard AS (2012). Interim scoring for the EQ-5D-5L: mapping the EQ-5D-5L to EQ-5D-3L value sets. Value Health 15(5):708-15.
Is there data published comparing the EQ-5D-3L and the EQ-5D-5L?
Yes. Please see here for a collection of webpages on this topic.
What is a value set?
A list of the value for every possible EQ-5D profile within a given descriptive system. For example, a value set for the EQ-5D-5L shows a value for each of the 3,125 states that are described by it. These values are usually calculated using an algorithm that assigns a score to each level in each dimension, sometimes including adjustments for interactions between the dimensions.
As value sets represent the average values of a sample of people, for example the general public of a particular country, it is important to state which value set is being used.
Value sets are also sometimes referred to as ‘tariffs’.
How are value sets obtained?
EQ-5D value sets are created by conducting a valuation study. In an EQ-5D valuation study, respondents (often members of the general public) are asked to indicate how good or bad some of the EQ-5D health states are. The answers are then combined into a statistical model, with which the value set is created.
Why are general population values sets used?
To undertake a utility analysis, you will need to use a value set. Generally speaking, utility analysis requires a value set based on preferences from a general population. The rationale behind this is that the values are supposed to reflect the preferences of local taxpayers and potential receivers of healthcare. The EQ-5D-5L value sets are therefore based on the values of the general population.
What is the preferred standard for designing a valuation study?
For the EQ-5D-5L, the preferred methodology for conducting valuation studies is provided in the EQ-VT protocol. If you are interested in conducting an EQ-5D-5L (or EQ-5D-3L) valuation study, please contact the EuroQol Office.
What is the difference between a value set and an interim “crosswalk” value set?
A value set is based on a valuation study where respondents indicate how good or bad some of the EQ-5D health states are. A crosswalk value set is one that has been created for the EQ-5D-3L and then adapted to fit the EQ-5D-5L descriptive system.
If there is no value set for my country, I am supposed to use an existing value set for a similar population. How do I assess whether a population is sufficiently similar?
Please see this webpage on choosing a value set. Many factors determine if another country’s value set can be used, such as geography, religion, language, level of development of the country, healthcare system etc. In addition, local HTA guidelines may come into play. Therefore, it is advised to contact local regulatory authorities about their requirements.
Please note, if a standard EQ-5D-5L value set is not available for your country, then an interim “crosswalk” value set can be used, if available. A crosswalk value set is one that has been created for the EQ-5D-3L and then adapted to fit the EQ-5D-5L descriptive system. More information on the crosswalk can be found here.
What is the difference between the VAS, TTO and DCE techniques? Can they all be used to generate a quality adjusted life year (QALY) score?
|The time trade-off (TTO), visual analogue scale (VAS) and discrete choice experiment (DCE) value sets differ in the technique used to elicit the values for the models.
In the TTO task, respondents are asked to imagine they live in a certain suboptimal health state for 10 years and then to specify the amount of time they would be willing to give up to live in full health instead. For example, someone might consider that 8 years in full health is equivalent to 10 years in the suboptimal health state.
The VAS technique asks people to indicate where they think a health state should be positioned on a vertical thermometer-like scale ranging from best imaginable health to worst imaginable health.
The DCE asks people to choose between two (or more) health states of varying severity across the five EQ-5D health domains (e.g. which is better, state A  or state B ?).
There has been much discussion about the theoretical and empirical properties of these three methods, and whether it is justified to calculate QALYs using values based on these methods, although all three techniques have been used to calculate QALYs. Currently, EQ-5D-5L value sets which are developed using the EQ-VT platform are based either on a combination of TTO and DCE values, or on TTO values only.
Please note that this is a large subject area and the brief answer provided above includes minimal details. For further information, the reader is encouraged to review the literature.
How can I obtain the EQ-5D-3L instrument?
If you have already seen the EQ-5D-5L and/or have decided to go ahead and use it, please register your study/project/trial first, by completing the EQ-5D registration form. The EuroQol Office will then contact you by e-mail and inform you about the terms and conditions which apply if you decide to use the EQ-5D, including licensing fees (if applicable). Please allow approximately 5 working days to receive this reply.
Once I have registered, what will be included in the contents of the EQ-5D package of information that will be sent to me? If in a digital mode of administration, how will that be shared with me/in what form?
The EuroQol Office team will determine if a license agreement needs to be drawn up and whether a license fee is applicable, in accordance with our EQ-5D User License Policy (see here).
EQ-5D paper versions will be provided as a Word document. For electronic versions, an Excel sheet will be provided with the EQ-5D labels, together with a document describing the EQ-5D electronic representation standards. The EQ-5D Demo versions on the website were created fully in line with our standards, so you can check how EQ-5D should look like on your system.
I am not conducting a study but would like to use the EQ-5D to measure routine clinical outcomes or to set-up a registry. Do I still need to register?
Yes, the EQ-5D is subject to copyright protection. Anyone interested in using the instrument should first register with EuroQol, as you can only obtain EQ-5D by completing the EQ-5D Registration Form. We can then provide you with the EQ-5D versions, languages and modes of administration you require. Please note, you are not obliged to purchase the EQ-5D by registering.
Do I have to pay for using the EQ-5D-5L instrument?
Licensing fees are determined by the EuroQol Office based on the user information provided in the registration form. If applicable, the size of the license fee depends on the type of study, funding source, sample size and number of requested EQ-5D versions and languages. You are not obliged to purchase the EQ-5D by registering. The EQ-5D user license policy is available on the EuroQol website.
Is the EQ-5D-5L a copyrighted instrument?
Yes. Please note that without the prior written consent of the EuroQol Office, you are not permitted to use, reproduce, alter, amend, convert, translate, publish or make available in whatever way (digital, hard-copy etc.) the EQ-5D-5L and related proprietary materials.
The EuroQol Research Foundation stresses that any and all copyrights in the EQ-5D, its (digital) representations, and its translations are exclusively vested in the EuroQol Research Foundation. EQ-5D™ is a trade mark of the EuroQol Research Foundation.
Am I allowed to reproduce the EQ-5D in a publication or on the website?
No, without the prior written consent of the EuroQol Office, you are not permitted to use, reproduce, alter, amend, convert, translate, publish or make available in whatever way (digital, hard-copy etc.) the EQ-5D and related proprietary materials. Please contact the EuroQol Office if you would like to reproduce EQ-5D.