EQ-5D is 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 and population health surveys. EQ-5D assesses health status in terms of five dimensions of health and is considered a ‘generic’ questionnaire because these dimensions are not specific to any one patient group or health condition. EQ-5D can also be referred to as a patient-reported outcome (PRO) measure, because patients can complete the questionnaire themselves to provide information about their current health status and how this changes over time. ‘EQ-5D’ is not an abbreviation and is the correct term to use when referring to the instrument in general.[1]
EQ-5D is widely used around the world in clinical trials and real-world clinical settings, population studies, and health economic evaluations. By mid-2020, the number of EQ-5D studies registered with the EuroQol Group totalled over 39,000. These comprised over 80 clinical areas and related to surgical procedures, hospital waiting lists, physiotherapy, general practice and primary care, and rehabilitation. The number of annual requests to use EQ-5D is approximately 5000, and EQ-5D data have been reported in over 8000 peer-reviewed papers over the past 30 years.[2]
EQ-5D can be used for a variety of purposes.
EQ-5D is recommended by many health technology assessment (HTA) bodies internationally as a key component of cost-utility analyses.[3]
EQ-5D was developed by the EuroQol Group, and its distribution and licensing are managed by the EuroQol Research Foundation. The EuroQol website [4] provides detailed information and the latest developments about EQ-5D including guidance for users, a list of available language versions and value sets by country/region, population norms, and key EQ-5D references. It also explains how to obtain the questionnaire. Those wishing to use EQ-5D must first register their study or trial via the website, using the page ‘How to obtain EQ-5D’,[5] which has more detailed information about registering, including an animated video. EQ-5D is provided without charging a license fee to non-commercial organisations after they have registered (approximately 95% of users), while commercial users are charged a fee. Registering a study does not obligate the purchase of an EQ-5D licence, but it enables the EuroQol Research Foundation to provide further information relevant to the type of study proposed, including terms and conditions (and licence fees if applicable).