Journal of Clinical Epidemiology 58 (2005) 338–349
Activities of daily living (ADL) and instrumental activities
of daily living (IADL) items were stable over time in
a longitudinal study on aging
, Trudy Mallinson
, Vanessa M. Barbosa
Department of Occupational Therapy, University of Illinois at Chicago (MC 811), 1919 West Taylor Street, Chicago, IL, 60612, USA
Rehabilitation Institute of Chicago, 345 East Superior Street, Chicago, IL 60611, USA
Pathways Center, 2591 Compass Road, Suite 100, Glenview, IL 60026
Accepted 4 October 2004
Objective: The purpose of this analysis was to examine the stability over time of the activities of daily living (ADL) and instrumental
activities of daily living (IADL) items in the Aging in Manitoba (AIM) Longitudinal Study and to evaluate the existence of differential item
functioning across settings (home, nursing home).
Study Design and Setting: The study used data from 607 participants of the AIM Longitudinal Study who were more than 85 years
of age in 1996 and who had complete data from 1983, 1990, and 1996 for all ADL and IADL items. Rasch analysis was used to examine
how the rating scale of the ADL and IADL items was used by participants, and to determine if the ordering of items remained stable across
three time periods (1983, 1990, 1996) and the two different settings (home, nursing home).
Results: The rating scale worked best when dichotomized into “received no assistance” and “receives assistance.” Except for four
items (making tea, making meals, doing nursing care, and going outside in any weather), the items were stable across administration
periods, and across settings.
Conclusion: The AIM can be used to evaluate changes in disability over time and may have the potential to identify those at risk for
transitions in care.
2005 Elsevier Inc. All rights reserved.
Keywords: Measurement; Oldest old; Longitudinal research; Rasch analysis; Activities of daily living; Instrumental activities of daily living
Longitudinal cohort studies provide the opportunity to
track changes in people over time and therefore can inform
practice and policy related to older adults. Currently, there
are approximately 50 longitudinal studies of aging interna-
tionally . Although each study has a slightly different
focus, all provide the opportunity to measure change over
time and investigate developmental aspects of old age as
changes occur. One of these studies, the Aging in Manitoba
Longitudinal Study (AIM), has been running continually
since 1971 and its ﬁndings have been used extensively by the
Government of Manitoba to plan services for the older adults
living in the province . One area of particular interest
has been the patterns and predictors of long-term care use.
* Corresponding author. Tel.: 312-996-4603; fax: 312-413-0256.
Dr. Barbosa was afﬁliated with Federal University of Minas Gerais,
Brazil at the time this study was conducted.
E-mail address: firstname.lastname@example.org (M. Finlayson).
0895-4356/05/$ – see front matter
2005 Elsevier Inc. All rights reserved.
Studies of long-term care use commonly examine the
role of changes in self-reported functional status for
determining the type and extent of long-term care used by
an older adult [3–5]. A key challenge for this work is the
potential for substantive changes in how participants respond
to test questions over time. Advances in technology have
played an important role over the past 30 years in what it
means to be independent. Consider, for example, how the
use of microwave ovens, automatic washers and dryers, and
the Internet have inﬂuenced the ability to respond “I don’t
need any help” for tasks such as meal preparation, laundry,
shopping, and banking. To ensure that valid comparisons of
functional change can be made both within and across indi-
viduals over time, these potential shifts need to be explored
to ensure that changes in functional status are due to real
change in person ability rather than some other factor or
factors. Otherwise, ﬁndings from analyses will be biased,
and practices and policies modiﬁed in response may be
misguided and problematic.
Rasch measurement, a member of the class of item re-
sponse theories, provides a clear way to evaluate the stability