Katz Index of Independence in Activities of Daily Living

The Katz Index of Independence in Activities of Daily Living, introduced by Sidney Katz and colleagues in 1963, is the foundational measure of basic self-care function in older and chronically ill adults. It rates whether a person can perform six fundamental activities — bathing, dressing, toileting, transferring, continence, and feeding — independently or with help, and summarizes them into a single index of functional status. Katz's central empirical observation was that these activities are lost in a consistent order, from the most complex and socially learned (bathing) to the most primitive (feeding), and recovered in the reverse order, so the index reflects an underlying organized process of disability rather than a random list of tasks. Decades after its introduction it remains the reference standard for basic activities of daily living and a building block of geriatric and rehabilitation assessment.