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Terminology

The following table is a clarification of the EQ-5D nomenclature. The purpose is to define standards for the naming of concepts used in describing the EQ-5D and data produced by the EQ-5D. This forms part of a wider task of defining standards for the reporting of the EQ-5D.

 

TERM DESCRIPTION
EQ-5D A standardised measure of health-related quality of life developed by the EuroQol Group to provide a simple, generic questionnaire for use in clinical and economic appraisal or population health status surveys.
EQ-5D-3L Refers to either the EQ-5D-3L descriptive system or the EQ-5D-3L questionnaire.
EQ-5D-3L descriptive system Descriptive system for health-related quality of life states in adults, consisting of five dimensions (Mobility, Self-care, Usual activities, Pain & discomfort, Anxiety & depression), each of which has three severity levels that are described by statements appropriate to that dimension.
EQ-5D-3L questionnaire Standard layout for recording an adult person’s current self-reported health state. Consists of a standard format for respondents to record their health state according to the EQ-5D-3L descriptive system and the EQ VAS.
EQ-5D-5L Refers to either the EQ-5D-5L descriptive system or the EQ-5D-5L questionnaire.
EQ-5D-5L descriptive system Descriptive system for health-related quality of life states in adults, consisting of five dimensions (Mobility, Self-care, Usual activities, Pain & discomfort, Anxiety & depression), each of which has five severity levels that are described by statements appropriate to that dimension.
EQ-5D-5L questionnaire Standard layout for recording an adult person’s current self-reported health state. Consists of a standard format for respondents to record their health state according to the EQ-5D-5L descriptive system and the EQ VAS.
EQ-5D-Y The Youth version of the EQ-5D, suitable for younger people. Refers either to the EQ-5D-Y descriptive system or the EQ-5D-Y questionnaire.

An expanded level version of the EQ-5D-Y is currently being developed. Once this is completed, the current version of the EQ-5D-Y will become the EQ-5D-Y-3L.

EQ-5D-Y descriptive system Descriptive system for young peoples’ health-related quality of life states consisting of five dimensions (Mobility, Looking after myself, Doing usual activities, Having pain or discomfort, Feeling worried, sad or unhappy), each of which has three severity levels that are described by statements appropriate to that dimension.
EQ-5D-Y questionnaire Standard layout for recording a young person’s current self-reported health state. Consists of a standard format for respondents to record their health state according to the EQ-5D-Y descriptive system and the EQ VAS.
EQ-5D proxy questionnaires A questionnaire that records a person’s current health state as rated by a caregiver who knows the person well. Consists of a standard format for the proxy to record the person’s health state according to the relevant EQ-5D descriptive system and the EQ VAS.
EQ VAS A standard vertical 20 cm visual analogue scale, used in recording an individual’s rating of their overall current health-related quality of life. The scale ranges from 100 (‘the best imaginable health state’ or ‘the best health state you can imagine’) to 0 (‘the worst imaginable health state’ or ‘the worst health you can imagine’).
EQ-5D profile A description of a health state defined by one of the EQ-5D descriptive systems. This may be summarised by a series of five sentences, one for each dimension and stating the level within that dimension; or a label consisting of five ordinal numbers, one for each dimension (by convention, in the order these appear in the questionnaire), defining the severity level, where 1 means no problems.
EQ-5D self-reported health  A health state recorded by a respondent using any of the EQ-5D questionnaires or by an interviewer recording their responses on the questionnaire. This may be summarised in the same way as the EQ-5D profile.
EQ-5D proxy-reported health state A health state recorded by a proxy acting for the person experiencing it using any of the EQ-5D proxy questionnaires. This may be summarised in the same way as the EQ-5D profile.
EQ VAS score Score between 0 and 100 recorded by an individual for their current overall health-related quality of life using the EQ VAS.
EQ-5D value The value attached to an EQ-5D profile according to a set of weights that reflect, on average, people’s preferences about how good or bad the state is. Values are anchored at 1 (full health) and 0 (a state as bad as being dead) as required by their use in economic evaluation. Values less than 0 represent health states regarded as worse than a state that is as bad as being dead.

An EQ-5D value is also sometimes known as an ‘index’, ‘score’ or ‘utility’.

EQ-5D 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 3125 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’.

EQ-VT The EuroQol Valuation Technology. Software developed by the EuroQol Group to obtain values for the EQ-5D in computer-assisted personal interviews. The methods currently used in EQ-VT to obtain stated preferences for EQ-5D health states are time trade-off (TTO) and discrete choice experiments (DCE).
EQ-5D valuation questionnaire Questionnaire, of standard layout, consisting of the EQ-5D questionnaire plus the EQ-5D VAS for a selection of EQ-5D profiles, and a standard set of instructions.

The EQ-5D valuation questionnaire was used in early research to value EQ-5D-3L and is now rarely used. Descriptions of it and its components are included here for completeness and clarity.

EQ-5D VAS Visual analogue scale, of standard 20-cm layout, for recording an individual’s valuation of defined EQ-5D profiles. The scale ranges from 100 (‘the best imaginable health state’ or ‘the best health state you can imagine’) to 0 (‘the worst imaginable health state’ or ‘the worst health you can imagine’). This is used to obtain a respondent’s stated preference values, not to record their own health state.
EQ-5D VAS value Stated preference score recorded by an individual for an EQ-5D profile using the EQ-5D VAS.

 

(Version03JUN2020)

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