Reliability and validity of self-care and mobility accommodations measures in the National Health and Aging Trends Study.
OBJECTIVE
Comprehensive measures of disability accommodations have been lacking in national health and aging studies. This article introduces measures of accommodations developed for the National Health and Aging Trends Study, evaluates their reliability, and explores the validity and reliability of hierarchical classification schemes derived from these measures.


METHODS
We examined test-retest reliability for questions about assistive device use, doing activities less often, and getting help from another person with both percentage agreement and kappa (N = 111). Summary measures across activities and several hierarchical classification schemes (e.g., no accommodation, devices/activity reductions only, help) were developed. For the latter, we also evaluated validity by examining correlations with measures of capacity and demographic characteristics (N = 326).


RESULTS
Items about assistive device use and help in the last month were robust (most kappas 0.7-0.9). Activity reduction measures were moderately reliable (around 0.5) but still showed reasonable agreement. Reliabilities for summary measures were good for device use (0.78-0.89) and help (0.62-0.67) but lower, albeit acceptable, for activity reduction (0.53). Hierarchical classifications had acceptable reliability and levels demonstrated hierarchical properties.


CONCLUSIONS
National Health and Aging Trends Study's self-care and mobility accommodation measures offer ample reliability to study adaptation to limitations and can be used to construct a reliable and valid hierarchy.
Institute for Social Research, University of Michigan, Ann Arbor. vfreedma@umich.edu.
Vicki A
VA
Freedman
Department of Population, Family, and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Emily M
EM
Agree
Jennifer C. Cornman Consulting, Granville, Ohio.
Jennifer C
JC
Cornman
The Urban Institute, Washington, DC.
Brenda C
BC
Spillman
Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Judith D
JD
Kasper
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D006233:Persons with Disabilities; D005260:Female; D006262:Health; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D015203:Reproducibility of Results; D012648:Self Care / Q000592:standards*; D012656:Self-Help Devices / Q000592:standards*; D011795:Surveys and Questionnaires / Q000592:standards*
Disability; Measurement; Technology