Sources of disagreement between clinical (ICD-9) and operational (RDC, DSM-III) diagnosis of endogenous depression (melancholia).

In a sample of 173 depressed in-patients, the sources of disagreement between the clinical ICD-9 diagnosis of endogenous depression (ED) and the corresponding operational definitions of RDC and DSM-III were analyzed. The RDC definition of ED gave a significantly higher degree of concordance with the ICD-9 diagnosis of ED, than that of DSM-III. This difference was mainly due to the algorithm used in DSM-III. When empirically derived algorithms were applied to the diagnostic criteria of DSM-III and RDC, both criteria lists reached a higher degree of concordance with the ICD-9 diagnosis of ED. When the criteria lists of RDC and DSM-III were supplemented with cross-sectional criteria (psychotic features, incapacitation) and by course-related criteria (recurrence, bipolarity, primary episode, adequate personality, no precipitating stress), this did not result in significant enhancement of the degree of concordance.