Psychology RootsIndex of Independence in Activities of Daily Living (Index of ADL)
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About Index of Independence in Activities of Daily Living
Scale Name
Index of Independence in Activities of Daily Living (Index of ADL)
Author Details
Sidney Katz
Translation Availability
English
Background/Description
The Index of Independence in Activities of Daily Living (Index of ADL), developed by Sidney Katz in 1959 and revised in 1976, is a 6-item clinician-rated scale designed to assess functional independence in basic activities of daily living (ADLs) among adults, particularly those with chronic illnesses, disabilities, or elderly populations. Published in JAMA (1963) and revised in Journal of Chronic Diseases (1976), the Index of ADL evaluates six domains: Bathing, Dressing, Toileting, Transferring (e.g., bed to chair), Continence, and Feeding. It is used to measure functional status, predict care needs, and evaluate rehabilitation outcomes, especially in geriatric and rehabilitation settings.
Each domain is rated dichotomously (Independent = 1, Dependent = 0) based on whether the individual can perform the activity without assistance, as assessed through observation or interview. Total scores range from 0–6, with higher scores indicating greater independence (6 = fully independent, 0 = fully dependent). The Index was validated with 1,000 elderly and chronically ill patients (mean age ≈ 65–80 years, mixed gender, U.S.-based), showing that scores ≥4 predict community living, while scores ≤2 often indicate need for institutional care. It correlates strongly with the Barthel Index (r ≈ 0.80–0.90) and moderately with the Functional Independence Measure (r ≈ 0.70–0.85). The scale is used in geriatrics, rehabilitation medicine, and clinical psychology to assess functional capacity and guide care planning. The scale is freely available from original publications.
Administration, Scoring and Interpretation
- Obtain the Index of ADL from Katz et al. (1963, 1976) or authorized sources (e.g., JAMA, Journal of Chronic Diseases), ensuring ethical permissions.
- Explain to participants (adults with disabilities or elderly) or caregivers that the scale assesses daily functioning, emphasizing confidentiality and voluntary participation.
- Administer the 6-item scale in a clinical, rehabilitation, or community setting via observation and/or interview, rating each ADL based on current performance without assistance.
- Estimated completion time is 5–10 minutes, depending on assessment method.
- Ensure a private, supportive environment; provide rehabilitation or mental health resources (e.g., support services) and adapt for accessibility (e.g., simplified explanations) if needed.
Reliability and Validity
The Index of ADL demonstrates robust psychometric properties (Katz et al., 1976; Spector et al., 1987). Inter-rater reliability is high (r ≈ 0.90–0.95), supported by clear dichotomous scoring, based on samples of 100–200 elderly patients. Test-retest reliability is strong (r ≈ 0.85–0.90 over 1–2 weeks). Internal consistency is moderate (Cronbach’s alpha ≈ 0.70–0.80) due to the scale’s brevity.
Convergent validity is evidenced by correlations with the Barthel Index (r ≈ 0.80–0.90), Functional Independence Measure (r ≈ 0.70–0.85), and PULSES Profile (r ≈ 0.65–0.80). Criterion validity is shown by its ability to predict outcomes like hospital discharge or institutionalization (scores ≥4 vs. ≤2) and sensitivity to rehabilitation progress.
Discriminant validity is supported by weak correlations with cognitive measures (r < 0.20). The scale’s unidimensional structure focuses on physical functioning. Pairing with the Lawton IADL Scale or Mini-Mental State Examination enhances comprehensive assessment.
Available Versions
06-Items
Reference
Katz, S. (1963). The index of ADL: a standardized measure of biological and psychosocial function. J Am Med Assoc, 185, 914-919.
Katz, S., Ford, A. B., Moskowitz, R. W., Jackson, B. A., & Jaffe, M. W. (1963). Studies of illness in the aged: the index of ADL: a standardized measure of biological and psychosocial function. jama, 185(12), 914-919.
Important Link
Scale File:
Frequently Asked Questions
What does the Index of ADL measure?
It measures functional independence in six basic activities of daily living.
Who is the target population?
Adults with chronic illnesses, disabilities, or elderly in clinical or rehabilitation settings.
How long does it take to administer?
Approximately 5–10 minutes.
Can it inform interventions?
Yes, it assesses functional status to guide rehabilitation and care planning.
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