Exploring the use of EQ-5D “bolt-ons” in our real-world studies

When we are designing our real-world studies, the collection of health-related quality of life data is an essential component. Measuring HRQoL means looking at the physical, mental, emotional, and social impact that health status and health status changes have on our study participants. The evidence generated from our studies is used to shape research and drug development: we need, therefore, to ensure that we select the most appropriate instrument for its measurement.   

The EuroQol Group developed the EQ-5D instrument for assessing HRQoL in 1990¹. The instrument is now well-known and widely used to measure, compare, and value health status across disease areas. Participants complete the questionnaire that first asks them to categorize the severity with which they experience problems in five health domains (mobility, self-care, usual activities, pain/discomfort, anxiety/depression), and then asks them to evaluate their overall health on a scale from 0 (worst health imaginable) to 100 (best health imaginable).  

The original three-level EQ-5D (EQ-5D-3L) provides the respondent with three response options, or “levels”, for each of the health domains: no problems, some problems, or extreme problems. The newer five-level EQ-5D (EQ-5D-5L) offers a total of five response levels – no, slight, moderate, severe, or extreme problems – thereby improving the sensitivity of the EQ-5D compared with the previous three-level version. The development of “bolt-on” items, i.e., dimensions that can be appended to another “parent” instrument, stemmed from the observation that the EQ-5D performed less well in certain conditions, particularly in those affecting hearing and vision² 

At Vitaccess, we are currently conducting a study to quantify the burden experienced by caregivers of patients living with myasthenia gravis. We conducted extensive literature reviews and interviews with caregivers to identify and explore the areas of their life most greatly impacted by caring for someone with MG. This research led to the decision to not only use the EQ-5D-5L in this study, but also bolt-on health dimensions, including tiredness – a key issue for this group of caregivers. 

Several parallel studies have been conducted to investigate the usability and benefits of applying additional dimensions to the EQ-5D2,3,4, and the evidence generated so far has been used to explore whether the bolt-on items do in fact boost performance of the instrument in conditions where it previously may have performed less powerfully. It is exciting to be contributing to the ongoing research to assess suitability of the bolt-on items by implementing them in our own real-world studies.  

To find out more about our digital real-world evidence studies and learn how we could help you, contact us at info@vitaccess.com 

By Catherine Bottomley, Sam Llewellyn, & Fatemeh Amini 


¹ https://euroqol.org/eq-5d-instruments/eq-5d-3l-about/ 

² https://www.ncbi.nlm.nih.gov/books/NBK261620/ 

³ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4309886/ 

4 https://www.frontiersin.org/articles/10.3389/fmed.2021.707998/full 

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