Shifts in diagnostic frequencies during the years 1975-1999.

Data on discharge diagnoses was obtained from a state-supported mental hospital located in the mid-Atlantic region of the United States for the years 1975 through 1999. Results indicated that frequencies of diagnosis of major mental disorders changed significantly during this interval, with reciprocal changes between schizoaffective and affective disorders and schizophrenia. Percentages of total discharge diagnoses of major affective disorders increased threefold, diagnoses of schizoaffective disorders increased fivefold, and schizophrenia diagnoses decreased threefold during the interval of study. Several of these trends were contemporaneous with changes in successive editions of the Diagnostic and Statistical Manual of Mental Disorders. Additional factors that may have contributed to changes in diagnostic rates include increased access to disability payments, changes in third-party payment policies and institutional funding priorities, access to improved medications, paradigm shifts, and changes in actual incidence of the disorders. Consistent with changed social policies, length of stay decreased for all groups during the interval 1975-1999.