Validation and reliability testing of the EORTC QLQ-NMIBC24 questionnaire module to assess patient-reported outcomes in non-muscle-invasive bladder cancer

Background: Well-developed and well-tested patient-reported outcome measures for non-muscle-invasive bladder cancer (NMIBC) are required. Objective: To test and adapt the scale structure and explore the psychometric properties of the European Organisation for Research and Treatment of Cancer (EORTC) questionnaire for NMIBC. Design, setting, and participants: A total of 433 patients in the Bladder COX-2 Inhibition Trial (BOXIT) completed the EORTC QLQ-C30 and NMIBC questionnaires. BOXIT is evaluating the addition of celecoxib to standard treatment in high- and intermediate-risk NMIBC. Outcome measurements and statistical analysis: Multitrait scaling investigated and adapted the questionnaire scale structure and evaluated the reliability and validity of the revised scales, as well as responsiveness to change. Results and limitations: A total of 410 patients (94.7%) (79.3% men, 74.6% high risk) returned baseline forms, and the questionnaire response rate was 88.2%. Multitrait scaling confirmed six scales and five single items. Scales and items demonstrated significant differences between patients with good and poor performance status scores (p < 0.001). Men reported better sexual function than women (p < 0.001). Scale and single-item module scores were not highly correlated with QLQ-C30 scores (evidence of discriminant validity), and the module was responsive to changes in health over time. International and test-retest data are required. Conclusions: This study demonstrates the evidence-driven adapted scale structure and psychometric data of the EORTC QLQ-NMIBC24 module to use in clinical trials of patients with high- or intermediate-risk bladder cancer