A community ability scale for chronically mentally ill consumers: Part I. Reliability and validity.

The authors describe the development, reliability testing, and validation of a 17-item instrument that measures the level of functioning of chronically mentally ill persons living in the community. The Multnomah Community Ability Scale is designed to be completed by case managers. The instrument provides a measure of the consumer's severity of disability which can, in turn, be used to: (a) describe an agency's "case mix" of clients; (b) measure consumer progress; (c) assign clients to different levels of service; and (d) assist payors in determining reimbursement. The Multnomah Community Ability Scale is aimed specifically at persons with chronic mental illness, is sensitive to differences among individuals within this special population, and is quick and easy to complete. The scale's reliability and validity have been examined in detail. Inter-rater and test-retest reliability are good. Criterion variables such as length of psychiatric hospitalization and clinicians' global ratings correlated highly with scale scores. Finally, the instrument predicts subsequent state and local hospital admissions.