Progress in the classification of functional psychoses.

The three most widely used diagnostic systems in American psychiatry--the Feighner criteria, the Research Diagnostic Criteria, and DSM-III--appeared sequentially at 4-year intervals. The fact that the latter two systems each incorporated changes in essentially all diagnostic categories implied progress toward greater validity; however, this assumption has rarely been tested directly. To do this, the authors applied each of these three systems to 98 consecutively admitted patients with nonmanic psychoses. Although family history and 6-month follow-up data strongly supported the validity of diagnostic distinctions made in each of the three systems, they did not show increments in validity with successively developed criteria sets.