Unipolar depression: diagnostic inconsistency and its implications.

Major depressive disorder using Feighner et al. (Arch. Gen. Psychiatry 26, 57-63, 1972) and DSM-III or DSM-III-R criteria has proven to be a heterogeneous diagnosis. It apparently includes a wide variety of clinical conditions. This report, based upon the results of a multi-year blind follow-up of 500 randomly selected psychiatric outpatients focuses on certain problems associated with the diagnosis of primary unipolar affective disorders. At index, 141 patients received diagnoses of primary unipolar depression. At follow-up, only 62 (44%) of these received the same diagnosis, with an additional 14 (10%) receiving a diagnosis of undiagnosed: questionable primary unipolar depression, and 5 (4%) a diagnosis of bipolar disorder. Thus, about 43% received other diagnoses at follow-up: 35 (25%) diagnoses of secondary depression and 25 (18%) other diagnoses without indication of an affective component. Bipolar patients' stability was significantly better for those who were manic at intake.