Defining Quality of Life

Quality of life measurement has suffered from the lack of an accepted definition of the concept. A needs-based model of quality of life is described, in which quality of life is defined as being at its highest when most or all human needs are met. This model forms the basis of a new measure for the assessment of quality of life in depres-sion, the Quality of Life in Depression Scale (QLDS). The measure’s development and testing are described and it is shown to have good reliability and validity. The QLDS has a number of positive features: it is based on a coherent theory of quality of life, it is derived directly from relevant patients, it is short and easy to complete, and it is in an appropriate format fo r inclusion in economic analyses and suitable for translation into other European languages. The measure has been used successfully in a clinical trial in the Netherlands