The evaluation of health and medical care increasingly incorporates patient-based assessments. This book introduces the terminology used in the growing field of subjective health status measurement as well as the issues to be considered when using this form of assessment. The book presents the principles and methods of patient-assessed outcomes research. It outlines the possible uses for such data and the methods of assessing the reliability and validity of patient-based questionnaires. It describes established measures and summarises the principles for designing disease specific measures. It explains how to select measures for inclusion in studies and how to evaluate published articles which include them. This book provides not only an introduction to health status measurement but also a critical sense of the key issues in this area. It is essential reading for doctors and other health professionals doing research in general practice or hospital settings public health physicians health service researchers and managers and students of health and social sciences.