IADL: Instrumental Activities of Daily Living Scale

About the IADL

The Instrumental Activities of Daily Living (IADL) Scale was developed by M. Powell Lawton and Elaine M. Brody at the Philadelphia Geriatric Center in 1969 as part of a broader effort to comprehensively assess functioning in older adults. It remains one of the most widely used measures of functional status in geriatric and neuropsychological assessment.

The IADL is distinguished from the Basic Activities of Daily Living (ADL) scale by its focus on higher-order, complex activities that require cognitive and organizational capacity. These are activities that are typically affected earlier in the course of cognitive decline than basic self-care tasks such as bathing or dressing.

What the IADL measures

The IADL assesses eight domains of instrumental functioning:

1. Ability to use the telephone, including looking up numbers and making calls
2. Shopping, managing grocery or other purchases independently
3. Food preparation, planning, preparing, and serving meals
4. Housekeeping, maintaining a home to an adequate standard
5. Laundry, washing and handling personal clothing
6. Mode of transportation, using public or private transportation independently
7. Responsibility for own medications, preparing and taking medications at correct doses and times
8. Ability to handle finances, managing bank accounts, paying bills, budgeting

How to administer the IADL

The IADL can be administered as a clinician interview, a self-report questionnaire, or an informant report completed by a family member or caregiver. In populations with cognitive impairment or dementia, informant report is recommended as the primary data source, because affected individuals may lack insight into their functional difficulties.

IADL scoring and interpretation

Each item is scored on a graded scale reflecting degree of independence, typically 0 (dependent) to 1 (independent) per item in the standard binary scoring, yielding a total score range of 0–8.

A score of 8 means the person was rated independent on every activity; each point lower marks one activity in which they need help. Lawton and Brody (1969) did not publish severity bands or a cutoff for the total, so HiBoop shows no score bands for the IADL. Interpret the total, and which items were lost, against the person's premorbid functioning, physical health and living situation, and track change over time on the same version and informant.

Some adaptations score items on more than two levels for more granular assessment; totals from different scoring versions are not interchangeable.

Notes on Scoring and Gender

Lawton and Brody's original scale was designed with different item applicability based on gender (reflecting societal norms of the 1960s). Contemporary usage applies all 8 items regardless of gender, and clinicians should interpret results in the context of the client's premorbid functional role and capabilities.

Clinical Applications

The IADL is used across multiple settings:

• Geriatric assessment: Baseline and monitoring for dementia, MCI, and age-related functional decline
• Neuropsychological evaluation: As a functional outcome measure alongside cognitive testing
• Discharge planning: Hospital and rehabilitation settings to assess readiness for independent living
• Mental health: Monitoring functional impact of depression, anxiety, or psychotic disorders in older adults

Psychometric properties

• Reliability. In 702 community-dwelling adults aged 60 and over in Sri Lanka, internal consistency was very high (Cronbach's alpha 0.91), inter-rater agreement was very good, and factor analysis supported a single dimension (Siriwardhana et al., 2018). In a Greek sample of 132 adults, Cronbach's alpha was 0.890 (Tafiadis et al., 2023).
• Validity. IADL scores correlated with cognitive screens such as the MMSE (r = 0.764) and separated cognitively impaired from unimpaired groups (AUC 0.888) (Tafiadis et al., 2023).
• Across studies. A systematic review found the Lawton scale had the most published evidence of any extended ADL scale, suggesting excellent reliability, construct validity and internal consistency with medium criterion validity, though many studies had methodological issues (Kelbling et al., 2024).

Limitations

• The IADL reflects current functional status and may be influenced by physical health, motivation, or environmental factors beyond cognitive capacity
• Discrepancy between self-reported and informant-reported scores is clinically meaningful, informants often identify deficits that patients minimize
• For patients with dementia, informant report is recommended as primary data source
• The IADL is a functional screen, not a diagnosis; limitations may signal cognitive decline but require comprehensive clinical evaluation
• The original item set reflected 1960s gender norms, so item applicability should be interpreted against the person's premorbid roles