EQ-5D-5L

In 2005, a task force was formed within the so-called EuroQol Group to further develop the EQ-5D-3L and thereby improve it. The specific goal was to increase sensitivity and reduce ceiling effects. These efforts eventually led to the development of the EQ-5D-5L.1

Content

The task force decided to keep the number of 5 dimensions and to increase the number of possible answers from 3 to 5 levels. Evidence from 25 years of use confirmed the validity of the 5 chosen dimensions.1-6

The EQ-5D-5L, like its predecessor, is a Patient Reported Outcome (PRO) instrument that can generally assess the quality of life of patients, regardless of disease, via 6 questions. It also includes a vertical EQ visual analog scale (EQ VAS, 0-100 points) and a descriptive EQ-5D-5L system. The latter assesses the following 5 dimensions or subscales over 5 levels / response options.1

EQ-5D-5L 1

5 dimensions (1 item each)

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

5 level

  • Level 1: no problems… / pain… / anxiety…
  • Level 2: slight problems… / pain… / anxiety…
  • Level 3: moderate problems… / pain… / anxiety…
  • Level 4: severe problems… / pain… / anxiety…
  • Level 5: unable to / extreme problems… / pain… / anxiety…
EQ-5D-5L evaluation
Descriptive EQ-5D-5L system and EQ-5D-5L index

As with the EQ-5D-3L, the descriptive EQ-5D-5L system defines so-called EQ5D Health States. A total of 3125 (=55) different health states can be recorded. Depending on the level, a number is assigned to each dimension resulting in a 5-digit number combination.

Example: A patient has no problems with mobility (level 1), slight problems with self-care (level 1), moderate problems with general activities (level 3), moderate pain (level 3) and is not anxious. His EQ5D Health State is accordingly 12331. A completely healthy patient would have a number of 11111.

This 5-digit number can be converted into a numerical value using a special algorithm that is not publicly available. This score is called the EQ-5D-5L Index and represents the patient’s state of health. The algorithm for calculating the EQ-5D-5L Index is based on country-specific values for the EQ-5D-3L. Through crosswalk studies with a collective of 3691 patients, an adequate link has been established between them.

For calculations, the links have been translated into mathematical functions. Thus EQ-5D-5L crosswalk value sets have been created, with which the EQ-5D Health States or their 5-digit numbers can be used to calculate the respective EQ-5D-5L index. An index value of 1 represents the best possible state of health, while an index value of <0 (variable) represents the worst possible state of health.

Whether the patient’s specific EQ VAS score plays a role in the calculation of his or her EQ-5D-5L index cannot be determined due to the non-public algorithm.

EQ-VAS

The EQ-VAS score is measured on a scale of 0-100 points depending on where the patient has set his marker. 0 points indicates the worst possible state of health, whereas 100 points indicates the best possible state of health.

EQ-5D-3L strengths

The EQ-5D-5L is a validated and established questionnaire that can be implemented in clinical research and patient care without much effort due to its small size.7-14 EuroQol member studies have also shown that it has higher statistical reliability and sensitivity compared to EQ-5D-5L, while its ceiling effect is lower. Last but not least, it is able to differentiate between considerably more health states by its finer subdivision of response possibilities and is therefore even more significant.15-18

EQ-5D-3L limitations

Although being lower than at the EQ-5D-3L, a ceiling-effect is still detectable.19

EQ-5D-3L license

The use and evaluation of the EQ-5D-3L requires a license. The amount of the license fee depends on the study type, donor, cohort size and language.20

Conclusion

The EQ-5D-5L is a successful further development of the EQ-5D-3L, which has been validated many times and is still widely used today. Its strong significance, combined with its small size, provide ideal conditions for efficient use in clinical research and patient care.

SOURCES:

  1. Herdman M, Gudex C, Lloyd A, et al. Development and preliminary testing of the new five-level version of EQ-5D (EQ-5D-5L). Qual Life Res 2011;20:1727-36.
  2. Conner-Spady B, Cumming C, Nabholtz JM, Jacobs P, Stewart D. Responsiveness of the EuroQol in breast cancer patients undergoing high dose chemotherapy. Qual Life Res 2001;10:479-86.
  3. Konig HH, Ulshofer A, Gregor M, et al. Validation of the EuroQol questionnaire in patients with inflammatory bowel disease. Eur J Gastroenterol Hepatol 2002;14:1205-15.
  4. Luo N, Chew LH, Fong KY, et al. Validity and reliability of the EQ-5D self-report questionnaire in Chinese-speaking patients with rheumatic diseases in Singapore. Ann Acad Med Singapore 2003;32:685-90.
  5. Nowels D, McGloin J, Westfall JM, Holcomb S. Validation of the EQ-5D quality of life instrument in patients after myocardial infarction. Qual Life Res 2005;14:95-105.
  6. Schweikert B, Hahmann H, Leidl R. Validation of the EuroQol questionnaire in cardiac rehabilitation. Heart 2006;92:62-7.
  7. Scalone L, Ciampichini R, Fagiuoli S, et al. Comparing the performance of the standard EQ-5D 3L with the new version EQ-5D 5L in patients with chronic hepatic diseases. Qual Life Res 2013;22:1707-16.
  8. Kim SH, Kim HJ, Lee SI, Jo MW. Comparing the psychometric properties of the EQ-5D-3L and EQ-5D-5L in cancer patients in Korea. Qual Life Res 2012;21:1065-73.
  9. Janssen MF, Pickard AS, Golicki D, et al. Measurement properties of the EQ-5D-5L compared to the EQ-5D-3L across eight patient groups: a multi-country study. Qual Life Res 2013;22:1717-27.
  10. Golicki D, Niewada M, Buczek J, et al. Validity of EQ-5D-5L in stroke. Qual Life Res 2015;24:845-50.
  11. Golicki D, Niewada M, Karlinska A, et al. Comparing responsiveness of the EQ-5D-5L, EQ-5D-3L and EQ VAS in stroke patients. Qual Life Res 2015;24:1555-63.
  12. Pan CW, Sun HP, Wang X, et al. The EQ-5D-5L index score is more discriminative than the EQ-5D-3L index score in diabetes patients. Qual Life Res 2015;24:1767-74.
  13. Nolan CM, Longworth L, Lord J, et al. The EQ-5D-5L health status questionnaire in COPD: validity, responsiveness and minimum important difference. Thorax 2016;71:493-500.
  14. Sakthong P, Sonsa-Ardjit N, Sukarnjanaset P, Munpan W. Psychometric properties of the EQ-5D-5L in Thai patients with chronic diseases. Qual Life Res 2015;24:3015-22.