The need for standardization of psychiatric assessment. The epidemiological point of view.

"Comparative psychiatry", which Kraepelin advocated 70 years ago, evolves today through the development of the epidemiological apporach in mental health. But its development is still hampered, by two methodological difficulties: 1. problems of definition of the "case"; 2. problems of evaluation, measure and classification of mental disorders. This has emphasized the need for an international common language for the description of mental health problems. The chapter V--Mental Disorders--of the International Classification of Diseases, in its 9th revision, illustrates the importance of such action. But the agreement on a diagnostic classification is only partially resolving the problem, because the concrete value of the classification is dependent on the reliability and validity of primary data on the patient. The World Health Organization is actively contributing to the standardization of assessment instruments; the Mental Health programme emphasizes the need for further efforts to elaborate a common language in mental health, both among psychiatrists from different countries, and between psychiatrists and planners of public health and other mental health personnel.