General hospital psychiatric units have served an important role
in treating persons with mental illness since their beginnings
in London in the late 1720s and in the United States in 1902 (1)
and their establishment in major U.S. teaching hospitals in the
1930s (2). The number of psychiatric units in the country grew
rapidly in the 1940s and 1950s, and by 1963 more patients were
treated on general hospital psychiatric units than in public
mental hospitals (1). The quality of psychiatric care provided
on psychiatric units is higher than that provided on general
hospital wards (3,4,5), yet psychiatric treatment on general
wards is still common, even for patients with severe disorders
(6). Little is known about the factors that influence the
decision to treat a patient on a psychiatric unit or on a
general ward. Although in theory this decision should be made
solely on the basis of clinical need, other patient and provider
characteristics may have a role. Greenhill (1) suggested in 1979
that less than 10 percen