Differences in Patient-Reported Outcomes That Are Most Frequently Detected in Randomized Controlled Trials in Patients With Solid Tumors: A Pooled Analysis of 229 Trials

Objectives: Patient-reported outcome (PRO) measurements used in cancer research can assess a number of health domains. Our primary objective was to investigate which broad types of PRO domains (namely, functional health, symptoms, and global quality of life [QoL]) most frequently yielded significant differences between treatments in randomized controlled trials (RCTs). Methods: A total of 229 RCTs published between January 2004 and February 2019, conducted on patients diagnosed with the most common solid malignancies and assessed using the European Organization for the Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-C30, were considered. Studies were identified systematically using literature searches in key electronic databases. Unlike other PRO measurements typically used in RCTs, the scoring algorithm of the multidimensional EORTC QLQ-C30 allowed us to clearly distinguish the 3 broad types of PRO domains. Results: In total, 134 RCTs (58.5%) reported statistically significant differences between treatment arms for at least 1 of the QLQ-C30 domains. Most frequently, differences were reported for 2 or all 3 broad types of PRO domains (78 of 134 trials; 58.2%). In particular, 35 trials (26.1%) found significant differences for symptoms, functional health, and global QoL, 24 trials (17.9%) for symptoms and functional health, 11 trials (8.2%) for functional health and global QoL, and 8 trials (6.0%) for symptoms and global QoL. The likelihood of finding a statistically significant difference between treatment arms was not associated with key study characteristics, such as study design (ie, open-label vs blinded trials) and industry support. Conclusions: Our findings emphasize the importance of a multidimensional PRO assessment to most comprehensively capture the overall burden of therapy from the patients' standpoint.