PurposeThe aim of this study was to assess the measurement properties of the 5-level classification system of the EQ-5D (5L), in comparison with the 3-level EQ-5D (3L).MethodsParticipants (n = 3,919) from six countries, including eight patient groups with chronic conditions (cardiovascular disease, respiratory disease, depression, diabetes, liver disease, personality disorders, arthritis, and stroke) and a student cohort, completed the 3L and 5L and, for most participants, also dimension-specific rating scales. The 3L and 5L were compared in terms of feasibility (missing values), redistribution properties, ceiling, discriminatory power, convergent validity, and known-groups validity.ResultsMissing values were on average 0.8 % for 5L and 1.3 % for 3L. In total, 2.9 % of responses were inconsistent between 5L and 3L. Redistribution from 3L to 5L using EQ dimension-specific rating scales as reference was validated for all 35 3L–5L-level combinations. For 5L, 683 unique health states were observed versus 124 for 3L. The ceiling was reduced from 20.2 % (3L) to 16.0 % (5L). Absolute discriminatory power (Shannon index) improved considerably with 5L (mean 1.87 for 5L versus 1.24 for 3L), and relative discriminatory power (Shannon Evenness index) improved slightly (mean 0.81 for 5L versus 0.78 for 3L). Convergent validity with WHO-5 was demonstrated and improved slightly with 5L. Known-groups validity was confirmed for both 5L and 3L.ConclusionsThe EQ-5D-5L appears to be a valid extension of the 3-level system which improves upon the measurement properties, reducing the ceiling while improving discriminatory power and establishing convergent and known-groups validity.

This study has developed the EQ-PSO questionnaire to support future psoriasis research and has informed the development of future bolt-on versions of the EQ-5D questionnaire.

The conceptual model illustrates the wide-reaching impact of SLE symptoms on a patient's HRQL, and the potential broad impact of a treatment that improves SLE symptoms.

The conceptual model developed in this study illustrates the many aspects of MM and its treatment and how they can have a negative impact on patients' HRQL.

Fatigue is a hallmark symptom of systemic lupus erythematosus (SLE), often associated with flares, side effects of treatment, and extensive organ damage and may have a significant impact on health-related quality of life (HrQoL). To date, the experience of fatigue in patients with SLE is underexplored. This study explored the experience of fatigue in patients with SLE and its impact on their lives through qualitative interviews. This cross-sectional qualitative study was conducted with 22 adult patients with SLE, recruited from two clinical sites in the United States. In-person semi-structured interviews were conducted and thematic analysis was performed focusing on the experience of fatigue in SLE. Results indicated that 21 out of 22 patients experienced fatigue due to SLE. Patients reported that fatigue was variable in nature in terms of both severity and frequency. Fatigue was described as having an impact on multiple aspects of a patient's life: emotions, cognition, work, activities of daily living, leisure activities, social activities, and family activities. Understanding how patients with SLE describe the symptom of fatigue and how it impacts their lives is the key to better understanding how to measure fatigue in clinical studies evaluating new treatments for SLE.