Presentation (CTI)

OBJECTIVES: Responder and time-to-event analyses of patient-reported outcome (PRO) data rely on threshold values—such as minimal important differences (MIDs)—to classify patients as improved or deteriorated. Despite growing adoption, selecting, applying, and reporting these thresholds remain inconsistent. This scoping review aimed to evaluate how responder and time-to-event thresholds are defined, applied, and reported in randomized controlled trials (RCTs) involving breast cancer patients, published between 2020 and 2024.
METHODS: A systematic search of PubMed identified 53 eligible RCTs including breast cancer patients and used responder or time-to-event analyses for PRO data. Data extraction focused on trial characteristics, PRO instruments, methods of threshold selection, and the transparency of reporting. Two independent reviewers conducted screening and data extraction, with discrepancies resolved by a third reviewer.
RESULTS: Most included studies were phase III trials, predominantly investigating targeted therapies. In 56.6% of studies, thresholds for responder or time-to-event analyses were selected ad hoc without justification. In 39.6% of trials, thresholds were supported by references to prior studies—either establishing the threshold or using it. Only 5.7% of trials provided a clear rationale for threshold selection. The most frequently cited source was Osoba et al. (1998), which proposed thresholds for the EORTC QLQ-C30 instrument. Differentiation of thresholds by PRO domain or between improvement and deterioration was infrequent. Reporting on derivation methods and their applicability was generally limited; few studies described anchor- or distribution-based methods or explained the relevance of the thresholds. Less than half of the trials (47.2%) explicitly stated that thresholds were used in their analyses.
CONCLUSIONS: This review reveals considerable variability and a lack of transparency in the use and reporting of PRO responder and time-to-event thresholds in breast cancer RCTs. There is a clear need for standardized methodological guidance and improved reporting practices to enhance the interpretability, comparability, and clinical relevance of PRO analyses in oncology research.