Health care professionals are increasingly convinced that the major objective of medical care for chronic diseases is the enhancement of health-related quality of life (HQOL) rather than the cure of disease or increased survival. HQOL is a multi-dimensional concept that includes the physical, psychological, and social functioning associated with an illness or its treatment. The inclusion of both biomedical and HQOL outcome measures in randomized clinical trials of new treatments assist physicians in selecting treatments that alleviate disease and improve the functional capability and well-being of patients.