Investigating potential bias in patient-reported outcomes in open-label cancer trials

Recent legislative efforts such as the 21st Century Cures Act have emphasized capturing and communicating the patient experience. Patient-reported outcome (PRO) assessments are one method to measure symptoms, function, and health-related quality of life. In 2009, the US Food and Drug Administration (FDA) released its first guidance on PROs, which states that PRO labeling claims in open-label trials can be problematic.1 Nonetheless, because of the highly symptomatic nature of cancer and its treatment, PRO measures have been incorporated in cancer trials for many years, and these trials are increasingly single-arm or open-label comparative studies unable to be blinded owing to differing administration routes or differential overt toxic effects. A frequent concern with PROs in open-label trials is that a patient’s perception of their symptoms or function may be influenced by knowledge of their assigned treatment. In light of the anticipated growth in PRO submissions to the FDA, we outline our thoughts on the ways in which open-label bias may arise and point to areas of research that might address this challenge.