EuroQol EQ-5D Quality of Life Scale

Abstract

The EQ-5D, developed by the EuroQol Group, is a standardized, generic instrument designed for measuring and valuing Health-Related Quality of Life (HRQoL). It is essential for generating health state utilities used in economic evaluation, particularly for calculating Quality-Adjusted Life Years (QALYs) in Health Economics. The instrument comprises two parts: a descriptive system covering five dimensions (Mobility, Self-Care, Usual Activities, Pain/Discomfort, and Anxiety/Depression) and a complementary Visual Analogue Scale (VAS). The scale is available in the original three-level version (EQ-5D-3L, 1990) and the more sensitive five-level version (EQ-5D-5L, 2005).

Keywords

Health-Related Quality of Life, HRQoL, EQ-5D, EuroQol Group, QALY, Health Economics, Utility Measurement, Visual Analogue Scale, VAS, Health Status.

Authors

The scale was developed collectively by the EuroQol Group, an international network of multidisciplinary researchers focused on developing standardized instruments for describing and valuing health states. Key individuals involved in the initial development and subsequent validation included researchers such as J. Brazier, R. Brooks, P. Kind, and N. Jones, among others listed in the foundational academic references.

Purpose

The primary purpose of the EQ-5D is to provide a concise, standardized measure of health status suitable for use in population surveys, clinical trials, and health technology assessment (HTA). Its structured format allows researchers to capture a respondent’s current health state accurately, generating data that can be converted into a single utility score.

This utility score is crucial for resource allocation decisions, as it enables the calculation of Quality-Adjusted Life Years (QALYs), facilitating comparisons of cost-effectiveness across different health interventions and diseases. The instrument is designed to be easily administered and understood across diverse cultural and linguistic backgrounds.

Construct

The EQ-5D measures the multi-dimensional construct of health-related quality of life (HRQoL). It operationalizes this construct through five specific, non-overlapping domains of health experience: Mobility, Self-Care, Usual Activities, Pain/Discomfort, and Anxiety/Depression. These domains are hypothesized to encompass the most critical aspects of health state valuation relevant to economic evaluation.

The descriptive system results in a health profile (e.g., 11111 for perfect health in EQ-5D-3L). The second component, the Visual Analogue Scale (VAS), serves as a complementary subjective measure, capturing the respondent’s overall perception of their health on a continuum from 0 (worst imaginable) to 100 (best imaginable), providing a global assessment of health status today.

Validity

The validity of the EQ-5D has been extensively supported through numerous cross-national studies. Construct validity is demonstrated by the instrument’s ability to differentiate between individuals known to have varying levels of health severity, such as patients with chronic conditions versus the general population (known-groups validity).

Furthermore, concurrent validity has been established through comparisons with other comprehensive HRQoL instruments, such as the SF-36 Health Survey Questionnaire (Brazier et al., 1993). The shift from the three-level to the five-level version (EQ-5D-5L) was specifically undertaken to enhance the scale’s sensitivity and discriminatory power, thereby improving its ability to detect subtle changes in health status and reducing the problematic ceiling effects observed in the EQ-5D-3L.

Reliability

Reliability of the EQ-5D is generally assessed through test-retest procedures, which confirm the stability and consistency of the descriptive system responses over time, provided the respondent’s actual health status has not changed. Due to the scale’s brevity (only five items), traditional internal consistency metrics like Cronbach’s Alpha are less meaningful than in longer, multi-item scales.

The reliability of the EQ-5D-5L, in particular, has been shown to be superior to the 3L version. The five response options offer finer granularity, allowing respondents to more accurately map their health state, which reduces random measurement error and improves the consistency of health state classification across repeated administrations.

Factor Analysis

Although the primary function of the EQ-5D is classification for utility generation rather than psychometric factor modeling, academic analyses frequently examine the underlying structure. Factor analysis generally supports the grouping of the five dimensions, sometimes yielding a two-factor model that broadly separates physical functioning (Mobility, Self-Care, Usual Activities) from mental and symptomatic distress (Pain/Discomfort, Anxiety/Depression).

However, the EuroQol Group maintains that the five dimensions represent distinct, non-redundant domains necessary for defining a health state. For utility calculations, the preference weights (value sets) derived from population valuation studies are applied to the five dimensions independently, reflecting the contribution of each dimension to the overall valuation of the health state.

Instrument

Test Type: Generic Health Status and Utility Measure

Format: Self-administered questionnaire consisting of a descriptive system (5 dimensions, either 3 or 5 response levels) and a Visual Analogue Scale (VAS).

Language Available: Over 200 language and dialect versions are available globally, ensuring wide international applicability in clinical trials and cross-cultural comparisons.

Population Group: General population, clinical cohorts, and patient populations across all major disease areas.

Age Group: Primarily used for adults (18+). Specific adaptations exist for children and youth (e.g., EQ-5D-Y).

Population Details: Widely employed internationally by government health agencies, such as NICE (UK) and organizations involved in Health Technology Assessment (HTA).

Test Methodology: The descriptive system requires respondents to select the statement that best describes their health today for each of the five dimensions. The VAS requires the respondent to mark their overall health status on a vertical thermometer-like scale ranging from 0 (worst imaginable health) to 100 (best imaginable health).

Keywords

Health Status, Utility Score, QALYs, EQ-5D-3L, EQ-5D-5L, Population Health, Clinical Trial Outcome, Cost-Effectiveness Analysis.

Authors

Author ORCID Identifier: N/A (Developed by the EuroQol Group collaboration.)

Affiliation Email addresses: N/A (Refer to the official EuroQol Group website for current contact information.)

Correspondence Address: N/A (Refer to the official EuroQol Group secretariat.)

Permissions & Fee and Test Year

The original EQ-5D-3L was first published in 1990. The updated version, EQ-5D-5L, was introduced in 2005.

Permissions and Fees: The EuroQol Group holds the copyright for the EQ-5D instrument. Users are required to register their use, and licensing fees may apply, particularly for commercial or industry-sponsored research. Non-commercial academic users often receive favorable terms or fee waivers upon registration.

Test Year: EQ-5D-3L (1990); EQ-5D-5L (2005).

Reference’s

• Brazier‚ J.‚ Jones‚ N.‚ Kind‚ P. (1993). Testing the validity of the Euroqol and comparing it with the SF-36 health survey questionnaire. Qual Life Res‚ 2:169–180.
• Brazier‚ J.E.‚ Walters‚ S.J.‚ Nicholl‚ J.P.‚ et al. (1996). Using the SF-36 and Euroqol on an elderly population. Qual Life Res‚ 5:195–204.
• Brooks‚ R. (1996). EuroQol: the current state of play. Health Policy‚ 37:53–72.
• EuroQol Group. (1990). EuroQol: a new facility for the measurement of health-related quality of life. Health Policy‚ 16:199–208.
• Greiner‚ W.‚ Weijnen‚ T.‚ Nieuwenhuizen‚ M.‚ et al. (2003). A single European currency for EQ- 5D health states. Results from a six country study. Eur J Health Econ; 4(3):222-231.
• McDowell‚ Ian. (2006). Measuring Health: A Guide to Rating Scales and Questionnaires‚ Third Edition. OXFORD UNIVERSITY PRESS
• Roset‚ M.‚ Badia‚ X.‚ Mayo‚ N.E. (1999). Sample size calculations in studies using the EuroQol 5D. Qual Life Res 8(6):539-49.
• Shaw‚ J.W.‚ Johnson‚ J.A.‚ Coons‚ S.J. (2005). US valuation of the EQ-5D health states: development and testing of the D1 valuation model. Med Care; 43(3): 203-220.
• The development of new research methods for the valuation of EQ-5D-5L. European Journal of Health Economics. Volume 14‚ Issue 1 Supplement‚ July 2013.
• Van‚Hout‚ B.‚ Janssen‚M.F.‚ Feng‚Y.S.‚ Kohlmann‚T.‚ Busschbach‚J.‚ Golicki‚D.‚ Lloyd‚A.‚ Scalone‚L.‚ Kind‚P.‚ Pickard‚A.S. (2012). Interim scoring for the EQ-5D-5L: mapping the EQ-5D-5L to EQ-5D-3L value sets. Value in Health‚ 15(5):708-15.

The original PDF measuring health can be downloaded here: www.a4ebm.org/sites/default/files/Measuring%20Health.pdf

The EQ-5D-5L User Guide (PDF) is available here: EQ-5D-5L User Guide (2015)

Items of the EuroQol EQ-5D Quality of Life Scale

EQ-5D-3L

Mobility

1. I have no problems in walking about
2. I have some problems in walking about
3. I am confined to bed

Self-Care

1. I have no problems with self-care
2. I have some problems washing or dressing myself
3. I am unable to wash or dress myself

Usual Activities (e.g.‚ work‚ study‚ housework‚ family or leisure activities)

1. I have no problems with performing my usual activities (e.g. work‚ study‚ housework‚ family or leisure activities.
2. I have some problems with performing my usual activities
3. I am unable to perform my usual activities

Pain / Discomfort

1. I have no pain or discomfort
2. I have moderate pain or discomfort
3. I have extreme pain or discomfort

Anxiety / Depression

1. I am not anxious or depressed
2. I am moderately anxious or depressed
3. I am extremely anxious or depressed

Visual analogue scale

To help people say how good or bad a health state is‚ we have drawn a scale (rather like a thermometer) on which the best state you can imagine is marked by 100 and the worst state is marked by 0.

We would like you to indicate on this scale how good or bad is your own health today‚ in your opinion. Please do this by drawing a line from the box “Your own health today” to whichever point on the scale indicates how good or bad your health state is.

EQ-5D-5L‚ 2005

MOBILITY

1. I have no problems in walking about 
2. I have slight problems in walking about 
3. I have moderate problems in walking about 
4. I have severe problems in walking about 
5. I am unable to walk about 

SELF-CARE

1. I have no problems washing or dressing myself 
2. I have slight problems washing or dressing myself 
3. I have moderate problems washing or dressing myself 
4. I have severe problems washing or dressing myself 
5. I am unable to wash or dress myself 

USUAL ACTIVITIES (e.g. work‚ study‚ housework‚ family or leisure activities)

1. I have no problems doing my usual activities 
2. I have slight problems doing my usual activities 
3. I have moderate problems doing my usual activities 
4. I have severe problems doing my usual activities 
5. I am unable to do my usual activities 

PAIN / DISCOMFORT

1. I have no pain or discomfort 
2. I have slight pain or discomfort 
3. I have moderate pain or discomfort 
4. I have severe pain or discomfort 
5. I have extreme pain or discomfort 

ANXIETY / DEPRESSION

1. I am not anxious or depressed 
2. I am slightly anxious or depressed 
3. I am moderately anxious or depressed 
4. I am severely anxious or depressed 
5. I am extremely anxious or depressed

Visual Analogue Scale Instructions:

• We would like to know how good or bad your health is TODAY.
• This scale is numbered from 0 to 100.
• 100 means the best health you can imagine.
• 0 means the worst health you can imagine.
• Mark an X on the scale to indicate how your health is TODAY.
• Now‚ please write the number you marked on the scale in the box below.