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

This study successfully validated the measurement properties of QLU-C10D, demonstrating its reliability and validity. Notably, the ceiling effects observed in the dimensions of C10D were lower than those observed in the dimensions of 5L, which can be attributed to the design of the questionnaire itself. Moreover, C10D exhibited a wider structural breadth compared to 5L. Interestingly, even individuals who were deemed completely healthy according to EQ-5D-5L reported difficulties when using disease-specific measurements. Specifically, among the 5L respondents, 25 patients selected '1111', whereas only 17 patients chose the same response in C10D (Table 3). Furthermore, C10D revealed more issues in the Physical, Social, and Fatigue dimensions. In contrast to the study conducted by Norma B. Bulamu et al., we observed differences in the results obtained from the two scales in the Physical dimension when patients responded to the questions. This discrepancy can be attributed to the fact that the Physical dimension in C10D encompasses more content from 5L, such as mobility, self-care, and usual activities. As a result, there is considerable overlap in the content of these two scales, and our convergent validity findings further support this, indicating higher correlations between theoretically corresponding domains and an overall strong association between the index scores.