Interpreting the BREAST-Q for Breast-Conserving Therapy: Minimal Important Differences and Clinical Reference Values.

BACKGROUND: The BREAST-Q is an important tool for evaluating patient satisfaction and quality of life in breast-conserving therapy (BCT) patients, but its clinical utility is limited by the lack of guidance on score interpretation. This study determines reference values and the minimal important difference (MID) for the BREAST-Q BCT module. METHODS: A retrospective review of BCT patients at Memorial Sloan Kettering Cancer Center from January 2011 to December 2021 was performed. Descriptive statistics were used to summarize median BREAST-Q scores. Distribution-based analyses estimated MIDs based on 0.2 standard deviation of baseline BREAST-Q scores and 0.2 standardized response mean of the difference between baseline and 1-year postoperative BREAST-Q scores. MIDs for different clinical groupings based on body mass index, radiation, and reexcision also were estimated. RESULTS: Overall, 8060 patients were included for determining reference values, and 5673 patients were included for estimating MIDs. Median BREAST-Q scores trended upwards and stabilized by 2 years after surgery for all domains except Physical Well-Being of the Chest, which decreased and stabilized by 2 years. A score interpretation tool, the Real-Time Engagement and Communication Tool, was created based on 25th percentile, median, and 75th percentile scores trajectories. All MID estimates ranged from 3 to 5 points; 4 points was determined to be appropriate for use in clinical practice and research. CONCLUSIONS: Reference values and MIDs are crucial to BREAST-Q score interpretation, which can lead to improved clinical evaluation and decision making and improved research methodology. Future research should validate this study's findings in different patient cohorts.