The term, Patient-Reported Outcomes, addresses the source of the report rather than the content. PROs are a useful terminology as an organizing tool for the many concepts and applications of self-reports in treatment evaluations. Lumping all the different concepts of PROs under an umbrella term such as Quality of Life or Health-Related Quality of Life confuses many persons and studies, because Ssuch disparate concepts are included in the label. PRO terminology permits primary identification that this information comes directly from the patient and avoids confusion in using one or more concepts as an over-arching term with little specification.

Some concepts can be measured from both a patient or an observer perspective, e.g., physical function. Others can only be patient-reported, e.g., pain. If a conclusion about pain is based on a non-PRO measure, it would be important to know. The term PRO makes it more likely that use of a PRO is considered in a clinical trial. Perhaps it is reasonable to confirm or add value to an objective or observed finding with a PRO. PROs in a daily diary format may capture daily variations in symptoms or function that can elucidate the mechanism of treatment effects.

PROs are important for measuring the impact of disease, treatment, health and social policies, and the progress of economic and social development. Reviewers conducting meta-analyses should specify and label the content and type of measure for every application of a PRO. Just like other outcomes, a major challenge faces reviewers in evaluating the clinical significance of PRO outcomes in studies.