This
article appeared in Aging Today, November/December 1997, copyright American
Society on Aging, 1997. It appeared in the newspaper's Research Today section,
aupported by a grant from the AARP Andrus
Foundation.
Implications for Research, Practice
Mapping Illnesses' Different Effects
Understanding how specific conditions of chronic illness affect particular functional abilities of elders is among the primary challenges of gerontological researchers. Sylvia E. Furner and colleagues at the University of Illinois School of Public Health focused on the effect of various long-term ailments on six instrumental activities of daily living (IADLs)--having difficulty with shopping, preparing meals, managing money, using the telephone, doing heavy housework and doing light housework.
In their report, "Medical Conditions Differentially Affect the Development of IADL Disability: Implications for Medical Care and Research" (The Gerontologist, August 1995), researchers Furner, Mark A. Rudberg and Christine K. Cassel stated, "Finding out what interventions may decrease the development of IADL disability in the future is imperative, as efforts are made to focus medical care on functional outcomes such as maintaining independence for older persons."
DATA DURING SIX YEARS
The research team examined longitudinal data on noninstitutionalized people aged 70 or older who were interviewed in 1986, '88 and '90 for the Longitudinal Study of Aging conducted by the National Center for Health Statistics. The participants had no IADL problems at their initial baseline interviews, which were done in 1984 as part of the Supplement on Aging of the National Health Interview Survey. Furner et al. correlated the development of IADL difficulties with nine medical conditions, such as stroke, arthritis and sensory impairments. Although the data did not include clinical examinations, the information-rich national sample yielded 2,056, 1,674 and 1,362 subjects for each of the follow-up interview years starting in 1986.
The most prevalent IADL disability was performing heavy housework (28.7% of subjects), while the least common problems among those studied were doing light housework (4.7%) and managing money (4.8%). One in three individuals reported developing at least one IADL difficulty during the six years of follow-up interviews.
To discern which of several chronic ailments may converge on a particular IADL disability over time, the authors used a model that mapped out the multivariate effects of particular diseases on certain disabilities. This chart also gave statistical weights for each impact to show the relative effect of a disabling condition, not just its frequency. Such a technique can help researchers spot troublesome interactions more easily.
The investigators found that "several medical conditions are independently associated with the specific IADL disabilities." For example, people with visual impairment and stroke were more likely than others to struggle with money management; hearing loss and general health status were related to difficulty with telephone use.
A key implication overlaying such individual effects, wrote the authors, is that "preventing one condition may not be sufficient to prevent future IADL disability, since . . . in most cases more than one condition is independently related to each outcome variable. Thus, multiple conditions may need to be treated concurrently if future IADL disability is to be affected." *