Population surveys of psychiatric disorder and the need for treatment.

A central purpose of psychiatric community surveys is the amplification of the clinical picture by studying non-referred cases. However, this demands an operationalized method of identifying cases. The choice of case definition determines both the prevalence of the disorder in the community and how community cases compare with referred cases. Usually case definitions are set with a fairly low threshold and include quite mild conditions. The recent use of the PSE and the DIS has led to reported prevalences of credible consistency. However, the relatively inclusive criteria for defining, for instance, affective disorders makes it difficult to equate prevalence with the need for treatment. Affective disorders in the clinic are associated with much greater impairment of social performance than non-referred cases. It is argued here that the evaluation in the community of the need for treatment and services should be done directly, by adapting new techniques of need assessment. Only thus can the necessary allocation of resources be estimated.