The minimum clinically important difference for EQ-5D index: a critical review

Abstract

The European Quality of Life-5 Dimensions Questionnaire (EQ-5D) is the most common instrument to value health outcomes under the patient’s perspective. Several studies have investigated whether observed changes are meaningful to patients, using a variety of approaches to estimate the minimum clinically important difference (MCID). This study provides an overview of the state of art of the estimation of the MCID for the three-level EQ-5D index based on the UK scoring algorithm, critically assessing the available evidence. The interest in estimation of MCID for the EQ-5D has been increasing in recent years. However, some additional standardization in the estimation procedures may be of value, in order to enhance the ability to make comparisons across measures and disease areas. Further methodological research might also contribute to reducing gaps between theory and practice.

Keywords::

• EQ-5D
• Euro QoL
• minimum clinically important difference
• minimum relevant difference
• review
• smallest worthwhile effect

Disclaimer

The views expressed here are those of the authors and not necessarily those of the funders.

Financial & competing interests disclosure

The Health Economics Research Unit is funded in part by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. The authors have other no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Health-related quality of life measures and especially European Quality of Life-5 Dimensions Questionnaire index are increasingly used in clinical studies.

• The minimum clinically important difference (MCID) is the minimum difference that the patient is able to recognize and appreciate.

• MCID can be used to define the optimal sample size in a clinical as well as to interpret results.

• Little empirical work has been done to estimate MCID for European Quality of Life-5 Dimensions Questionnaire index despite the widespread use of this measure.

• Many computational methods exist for MCID, leading to different results.

• Future research should focus on both methodological and empirical aspects in order to enhance knowledge and understanding, leading to potentially greater standardization.

Notes