A patient-reported outcome (PRO) is any report coming directly from patients, without interpretation by physicians or others, about how they function or feel in relation to a disease or treatment [1,2]. The field of PRO research has evolved considerably over the last 30 years from an initial focus on quality of life (QOL) to a more multifaceted study of different aspects of disease and therapeutic impact with a comprehensive theoretic framework, accepted methods, and diverse applications [3]. As medical treatments have progressed from lifesaving benefits to QOL-improving benefits, PROs have become increasingly important to patients and health-care providers.