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The measurement of instrumental ADL: content validity and construct validity
K Avlund1, K Schultz-Larsen, S Kreiner
1Institute of Social Medicine, University of Copenhagen, Denmark.
Aging (Milan, Italy)
|October 1, 1993
Summary
A new Instrumental Activities of Daily Living (IADL) measure effectively distinguishes functional abilities in older adults. Despite omitting some relevant items, it demonstrates good content and construct validity for this population.
Area of Science:
- Gerontology
- Health Sciences
- Sociology
Background:
- Functional ability assessments are crucial for the elderly.
- Existing measures often include Physical ADL (PADL) and Instrumental ADL (IADL).
- There is a need for IADL measures that can differentiate within the non-dependent elderly population.
Purpose of the Study:
- To test the content and construct validity of a new Instrumental ADL (IADL) measure.
- To assess if the new IADL measure can discriminate among elderly individuals who do not require assistance.
- To evaluate the IADL measure's ability to distinguish between actual performance and capability.
Main Methods:
- Data collected from 734 70-year-old individuals in Denmark.
- A new IADL measure with 30 activities, considering tiredness and reduced speed, was used.
- Construct validity was assessed using Rasch model item analysis; internal validity by item homogeneity.
Main Results:
- Rasch item analysis identified 14 items forming two distinct additive scales.
- The IADL measure demonstrated content validity and distinguished between elderly capabilities and actual actions.
- The measure effectively discriminated among non-dependent elderly individuals.
Conclusions:
- The developed IADL measure shows promise in assessing functional abilities in older adults.
- The measure exhibits good content and construct validity, differentiating performance levels.
- Omission of certain relevant items, like housework, presents a limitation and potential contradiction in criteria.