Quality of life measurement in the medical setting.

Quality of life became a paradigm in the medical setting two decades ago. Although 'humanistic' psychologists still maintain that what can be specified and measured is precisely what is not quality of life, time has shown that the major components of quality of life in health and disease can be measured with an acceptable internal as well as external validity. Quality of life in randomized clinical trials is now the third dimension to be measured, the other dimensions are efficacy of the drug and adverse drug reactions. Among the major areas of external validity quality of life scales (eg the PCASEE questionnaire and the Psychological General Well-Being Schedule) have discriminating validity (the discrimination between treatments), predictive-validity (the prediction of relapse of illness), and teological validity (defining goal of treatment).