US FDA patient-reported outcome guidance: great expectations and unintended consequences.

Release of the US FDA patient-reported outcome (PRO) guidance raised expectations within the pharmaceutical industry for the use of PRO measures in support of labeling claims. The FDA developed the guidance with admirable intent, and the recommendations within this document are based on sound scientific principles. However, implementation of the guidance has been somewhat inconsistent within the Study Endpoints and Label Development (SEALD) and across the various FDA-reviewing divisions. Industry and regulatory bodies need to work toward gaining common ground to best support registration of treatments that could extend patients' lives, reduce symptoms, and/or improve health-related quality of life. PROs are valuable tools in communicating these messages, and realistic implementation of the FDA PRO Guidance may truly facilitate this process.