Katz index of independence in ADL. Reliability and validity in short-term care

Abstract

This article deals with the Katz Index of Independence in Activities of Daily Living and presents a study of its reliability and validity carried out at a Department of Internal Medicine in Sweden. Enrolled nurses assessed independently 100 aged patients. Scalability and interobserver variability were tested with Guttman scale-analysis. The results indicated that the activities are ranked according to a cumulative scale and that the index is reliable. Patients independent in ADL had shorter hospitalization and were discharged home more often than were the dependent patients. This indicates that the scale is valid. One year later most dependent patients were either dead or living in institutions: thus the index has a predictive potential. The systematic errors of scale were used to refine the index for use in short-term care. It is recommended as a basic measure of functional ability among aged abled or disabled patients also in short-term care.