Reliability, validity, and change thresholds of the NCCN/FACT Bladder Symptom Index (NFBlSI-18) in patients with advanced urothelial cancer.

The NCCN/FACT Bladder Symptom Index-18 (NFBlSI-18) is a questionnaire used to assess quality of life for people with advanced bladder cancer. People with advanced bladder cancer who took part in the JAVELIN Bladder 100 study completed the NFBlSI-18 when they joined the study and after each treatment with avelumab maintenance or best supportive care. This study showed that NFBlSI-18 is suitable for capturing bladder cancer symptoms and is able to detect important changes in a person's quality of life over time. This study also provides thresholds for changes in NFBlSI-18 scores, which will be useful for future studies.