Screening and Diagnosis of Depression

Depressive symptoms are extremely common in the general population and, particularly, in the medically ill. The diagnostic criteria for a major depressive disorder set a clinical threshold for the forms of depression requiring specific treatment. However, the criteria require a specialised psychiatric interview and are difficult to use outside of psychiatry. For screening purposes, self-rating questionnaires have been proposed, but none have appeared to be completely satisfactory. There is much evidence that depression in the medically ill is frequently unrecognised and untreated. The diagnostic criteria for major depression are the essential tools for case identification and inclusion in studies (particularly if involving experiments in therapeutics, such as drug trials). However, they do not provide an adequate threshold for intensity of symptoms and, in some cases, should be supplemented by other instruments. It is only in recent years that it has become apparent that, despite effective treatments, the longer term outcome in depression is still problematic. Current treatment protocols appear to be largely inadequate in relapse prevention. Screening for depressive relapse and subclinical symptomatology that entails considerable prognostic value thus becomes of considerable value. Such screening requires a conceptual shift from current oversimplified views on assessment and course of depressive episodes based on psychometric principles to multimodal, clinically derived approaches according to clinimetric principles. Depression appears to be more and more a potentially chronic and greatly invalidating disease that represents a major challenge to modern healthcare.