QLU-C10D Measurement Properties and Comparison with EQ-5D-5L: A Validation Study

This study effectively validated the measurement properties of the QLU-C10D, demonstrating its reliability and accuracy. The dimensions of C10D exhibited lower ceiling effects compared to those of 5L, suggesting that the questionnaire's design contributed to this difference. Furthermore, C10D demonstrated a broader structural width compared to 5L. Notably, even patients considered completely healthy according to EQ-5D-5L reported issues when using disease-specific measurements. Table 3 revealed that out of 25 patients who chose '1111' in 5L, only 17 chose the same in C10D. C10D highlighted more concerns in the dimensions of Physical, Social, and Fatigue. In contrast to the study by Norma B. Bulamu et al., our findings also revealed discrepancies in the results obtained from the two scales in the Physical dimension, possibly attributed to the inclusion of additional content from 5L in C10D, such as mobility, self-care, and usual activities. Consequently, there is a significant overlap in the content of these two scales. This is supported by our convergent validity results, which indicated higher correlations between theoretically corresponding domains and an overall strong association between the index scores.