From patient-reported outcome scores to clinical meaning: defining thresholds for clinical importance for the EORTC QLQ-PR25 questionnaire for patients with prostate cancer

Background and Purpose Interpretation of patient-reported outcome scores remains challenging. Thresholds for clinical importance (TCIs) can facilitate score interpretation at the individual-patient level. We aimed to establish TCIs for the EORTC QLQ-PR25 to improve the interpretation of prostate cancer (PCa)-specific patient-reported outcomes in clinical practice and research. Methods In this prospective multicentre study, 261 patients with PCa from seven countries completed the EORTC QLQ-PR25 and anchor items assessing limitations in daily life, need for help/care, and worries caused by the respective symptom or problem. Receiver operating characteristic analyses were used to derive TCIs for the QLQ-PR25 scales, using a binary criterion for clinical importance based on the anchor items. Sensitivity analyses explored threshold robustness across patient subgroups. Results For five of the six QLQ-PR25 scales, ROC analyses showed acceptable to excellent discrimination, with AUC values ranging from 0.74 to 0.90. The corresponding TCIs showed sensitivity values between 0.62 and 0.88 and specificity values between 0.48 and 0.98. No meaningful threshold could be established for sexual activity (AUC = 0.48). Conclusions This study provides the first TCIs for a questionnaire assessing health-related quality of life in patients with PCa. These thresholds may improve interpretation of individual patient scores, support symptom screening and clinical decision-making, and facilitate the definition of clinically meaningful outcomes in clinical research.