"Quality of life": a brand new concept for research and practice in psychiatry.

Since the '70s, the assessment of quality of life (QOL) has grown from a 'small cottage' industry to a formal discipline within a coherent theoretical framework, accepted methods, and manifold applications. In recent years, QOL has become increasingly popular as a useful variable tailored to assess the overall impact of diseases and medical treatments from the patient's point of view. In this updating paper, we describe the most frequently used instruments, and discuss the conceptual and practical issues concerning QOL evaluation, as applied to the study of mental disorders. In addition, we present a unifying definition of QOL that has recently been developed by the World Health Organization. Finally, we conclude that QOL measures are potentially useful methods to be applied to research and clinical practice in psychiatry -- especially when used to demonstrate the impact of mental illnesses and the possible benefits of therapeutic interventions.