Abstract

Objectives

This study systematically compared the psychometric properties of 6 of the 5-level and 3-level EQ-5D bolt-ons (vision, breathing, tiredness, sleep, social relationships, and self-confidence).

Methods

Population Norms Study (POP-UP) is a longitudinal survey collecting general population data from United States, Canada, United Kingdom, Italy, Spain, Germany, the Netherlands, and Belgium. Respondents entered demographics and health conditions data and completed the EQ-5D-5L/3L with bolt-ons, Myasthenia Gravis Activities of Daily Living (MG-ADL), and Health Utility Index-3 (HUI-3). Psychometric properties included ceiling/floor, informativity, divergent and convergent validity, reliability, known-groups validity, and responsiveness.

Results

A total of 9,758 respondents completed the survey in 2021, and 4,839 respondents in 2023. The 5-level bolt-ons reduced ceiling effects by 35% and floor effects by 55% compared with the 3-level, with the largest reductions for vision and sleep (42%/57%) and the smallest for breathing (29%/44%). Informativity was higher for the 5-level bolt-ons (3%-11%) than 3-level (2%-9%), except for breathing (−2%). Most bolt-ons showed weak to moderate correlations with EQ-5D dimensions, except for social relationships, which correlated strongly with anxiety/depression (r = 0.61). Both measures showed strong convergent validity for breathing (5-level r = 0.68; 3-level r = 0.66) and lower for vision (5-level r = 0.37; 3-level r = 0.32). EQ-5D + 5-level and EQ-5D-5L + 3-level bolt-ons had excellent reliability (Intraclass Correlation Coefficients = 0.92-0.97). Adding bolt-ons did not significantly improve known-groups validity, except for breathing (relative efficiency EQ-5D + 5-level = 1.12; EQ-5D-5L + 3-level = 1.10). The 5-level bolt-ons improved responsiveness, detecting 47.1% more improvements and 55.7% more worsening over time.

Conclusions

All 6 of the 5-level EQ-5D bolt-ons outperformed the 3-level bolt-ons by reducing ceiling and floor, enhancing informativity, demonstrating divergent validity, and improving responsiveness.