This is the third in a series of five articles

Quality of life measures are increasingly used to supplement objective clinical or biological measures of disease to assess the quality of service, the need for health care, the effectiveness of interventions, and in cost utility analyses. Their use reflects a growing appreciation of the importance of how patients feel and how satisfied they are with treatment in addition to the traditional focus on disease outcomes. In this respect, quality of life measures capture patients' perspectives of their disease and treatment, their perceived need for health care, and their preferences for treatment and outcomes. They are hailed as being patient centred. But the challenge in measuring quality of life lies in its uniqueness to individuals. Many of the existing measures of quality of life fail to take account of this by imposing standardised models of quality of life and preselected domains; they are thus measures of general health status rather than quality of life.

Questions arise as to whether such measures are truly patient centred and to what extent they actually represent the quality of life of individual patients or groups of patients. Do they simply describe a patient's health in terms of what health professionals or society believe constitutes quality of life for people who are ill, something that may include factors that have little relevance to or importance for patients?

This paper explores the extent to which standardised quality of life measures accurately quantify an individual patient's quality of life. It debates whether newer, individualised approaches, which allow patients to define their quality of life in relation to their goals and expectations, are more appropriate.