Validity and performance of the Functional Assessment of Cancer Therapy-Bladder (FACT-Bl) among advanced urothelial cancer patients

PURPOSE: The recent increase in emerging novel therapies in the bladder cancer therapeutic area has increased the need for fit-for-purpose patient-reported outcome (PRO) measures for these patients. This study evaluates the psychometric properties of the Functional Assessment of Cancer Therapy-Bladder (FACT-Bl) in 182 patients with advanced urothelial cancer (UC) and fills an important gap by demonstrating its validity for use in clinical trials. METHODS: Data were collected as part of a multicentre, open-label study of durvalumab in patients with inoperable or metastatic solid tumours. Psychometric properties evaluated include item and subscale characteristics (including correlation analysis), reliability (estimated using Cronbach’s α), validity (by independent sample t test), responsiveness (using mixed models with repeated measures), and clinically meaningful changes using both anchor-based and distribution-based methods. RESULTS: One hundred and seventy-two patients completed the FACT-Bl questionnaire at baseline. Many individual items had floor or ceiling effects indicative of minimal symptoms and high functioning. The psychometric properties of the existing established scales were assessed and found to range from acceptable to very good. Internal consistency (most Cronbach’s α coefficients range 0.66–0.85) and stability (test–retest reliability) generally exceeded standards for good reliability (most estimated intraclass correlations [ICCs] exceeded 0.70, although ICCs for some items [e.g. emotional well-being, ICC 0.58; social well-being, ICC 0.66] were lower than 0.70). Evidence for known-group validity of relevant FACT-Bl subscales and total score was demonstrated by significant differences between groups defined by baseline tumour burden and quality of life scores (difference of FACT-Bl total between low/high tumour burden groups 11.72 (p = 0.001); difference between low/high QoL scores groups 30.51 (p < 0.0001)). The FACT-Bl subscale and total scores were responsive to changes in bladder cancer symptom severity. Clinically meaningful changes in FACT-Bl scores were estimated. CONCLUSIONS: Results support the use of the FACT-Bl within this patient population in future clinical research.