[Measuring quality of life in rheumatic disease. A critical appraisal]

The term quality of life (QoL) has been introduced to account for relevant non-clinical endpoints and the integration of patients' perspectives into treatment evaluation, amongst others. However, QoL is not a uniform, consistent scientific concept but an equivocal generic term for a field of interest. It can relate to such diverse aspects as living conditions, functioning, perception or appraisal of health-related states or general aspects of life. Any assessment of QoL must necessarily exclude relevant facets and assume comparability of basic important life themes in specific groups of people. Widespread instruments for QoL assessment in rheumatology, e.g. SF-36, EQ-5D or the Nottingham Health Profile, represent different QoL concepts (profiles vs. indices). However, they have in common a societal ideal of a physically capable, mentally healthy, socially integrated and functionally competent person. Before an assessment of QoL the aims of an assessment and the concepts of interest should be specified.