Translating the science of patient-reported outcomes assessment into clinical practice.

Patient-reported outcomes (PROs) are based on direct reporting by patients without the intervention of an observer. They include the self-assessment of functional status, symptoms, and other concerns such as needs and satisfaction with care. Health-related quality of life (HRQOL) assessment is a form of PRO and often includes both functional status and symptoms. The science underlying the assessment of HRQOL in clinical practice requires an understanding of the relationships between symptoms, functional status, and HRQOL, as well as instrument selection, and analysis and interpretation of the data. A modification of the Wilson and Cleary model is proposed to show the likelihood of bidirectional relationships between symptoms, functions, and HRQOL. Instrument selection should be based on the measurement properties of the instruments and patient populations in which they will be used. Analyses of data that allow a calculation of the proportion of patients who benefit from an intervention are preferred to analyses that show only the mean change in scores from baseline. HRQOL assessment in clinical practice has been shown to lead to a better understanding of patients' concerns with improvement in counseling and referral for required services. Potentially, HRQOL assessment should also be used to monitor the progress of a patient's disease and benefit from treatment.