Abstract: Objective This study aimed to evaluate the measurement attributes of the QLU-C10D scale in breast cancer patients,and provide the evidence for the application of the tool in the measurement of health effectiveness of breast cancer patients. Methods Since July 2022,the data of breast cancer patients in Harbin Medical University Cancer Hospital and the First Affiliated Hospital of Harbin Medical University were collected,and the utility values for the QLU-C10D and EQ-5D-5L were calculated based on the Chinese utility scoring system.The validity of the first collected sample data was evaluated by convergent validity and known-group validity,The data were collected again three months after treatment to evaluate the responsiveness of QLU-C10D in breast cancer patients. Results In terms of convergent validity,the theoretical correlation dimension between the QLU-C10D and EQ-5D-5L scale was higher than that of irrelevant dimensions.Among them,the correlation between pain in QLU-C10D scale and pain in EQ-5D-5L scale was the highest(r=0.546),while the correlation between insomnia in QLU-C10D scale and self-care in EQ-5D-5L scale was the lowest(r=0.219).In terms of known-group validity,the QLU-C10D scale had a relative efficiency(RE)greater than 1 in all groups(education level,residential address,frequency of physical examinations,economic pressures,and ECOG score).In terms of responsiveness,the QLU-C10D scale could effectively reflect the changes in health status of breast cancer patients after treatment,especially in the dimensions of role function(ES=0.415,SRM=0.645)and bowel problems(ES=0.433,SRM=0.708). Conclusion The QLU-C10D scale has good convergent validity,known-group validity and good responsiveness.It is a disease-specific health utility measurement tool that can be used for health utility measurement of breast cancer patients and health technology evaluation research.

Key words: QLU-C10D scale, Measurement attributes, Breast cancer, Validity, Reactivity