Outcomes research: an overview.

Outcomes research is increasingly important in contemporary medicine. Outcomes research differs from traditional clinical research in that outcomes are typically measured from the patient's perspective, and expanded measures of outcome are used, such as quality of life and cost-effectiveness. In this introduction to the special journal edition, the author will discuss the background behind outcomes research and describe several of its important aspects. Outcomes research consists of the clinical study of expanded, patient-based outcomes, as well as the study of populations, databases, and the delivery of health care. Outcomes research also includes the development of validated instruments to assess patient-based outcomes, development of disease severity staging systems, identification of comorbid conditions, and meta-analysis.