Defining and counting the chronically mentally ill.

The shifts in the pattern and locus of mental health care arising from the deinstitutionalization movement have resulted in a lack of definitive information on the scope of the problem of chronic mental illness. In addition, there is a lack of consensus on the boundaries that define the chronically mentally ill population, boundaries that can guide national policy-makers in a more scientific assessment of needs. In a national study following up the recommendations of the President's Commission on Mental Health, the authors developed a detailed definition of the chronically mentally ill population based on diagnosis, disability, duration of illness, and the institutional and community settings in which chronic mental patients may be found. They used prevalence data from a number of sources to arrive at a national estimate of between 1.7 million and 2.4 million in the target population, including 900,000 in institutions.