Establishing meaningful change thresholds for European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire CLL-specific module domain scores: An analysis based on the TRANSCEND CLL 004 study in patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma.

Introduction: The study aimed to establish meaningful thresholds at patient and group levels for the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire CLL-specific module (EORTC QLQ-CLL17) domain scores in adults with relapsed or refractory (R/R) chronic lymphocytic leukaemia (CLL). Material and methods: Data for the analysis were from the TRANSCEND CLL 004 study (NCT03331198). EORTC QLQ-CLL17 and selected anchor measures were assessed at baseline and multiple postbaseline visits up to 24 months after treatment initiation. Thresholds for each of the three EORTC QLQ-CLL17 domains were triangulated based on estimates derived from anchor- and distribution-based analyses, in accordance with published guidance. Results: The analysis included 62 patients with 240 observations across visits. Meaningful change thresholds for improvement and deterioration, respectively, at the patient level were determined to be -11/+11 for symptom burden, -16/+16 for physical condition/fatigue and -16/+13 for worries/fears on health and functioning. The meaningful change thresholds for improvement and deterioration at the group level mostly ranged between 0.3 and 0.5 of the standard deviation of baseline domain scores. Conclusions: These thresholds, based on EORTC QLQ-CLL17 domain scores, could help identify patients with meaningful changes in HRQOL and interpret treatment effects in future studies of treatments for adults with R/R CLL.