Abstract
From the traditional biological perspective, medical therapy is judged by its effects on survival or other indicators related to pathophysiology, such as growth or shrinkage of cancer masses. More recently, investigators have broadened their assessments of medical interventions (and conditions). So-called outcomes research explicitly recognizes that chronic diseases and their treatments may affect patients' lives in ways other than causing symptoms, organ dysfunction, and death. They may also impair patients' ability to perform activities of daily living, continue their usual social roles and interactions, and preserve their economic condition—each a plausible aspect of health-related quality of life.