Study finds: 'Gradient of Disability'
Linked to Household Income of Older Adults
Low-income Americans ages 55 to 84 are far more likely than their wealthier
peers to feel limited in doing basic physical activities such as climbing
stairs and lifting objects, according to a new study. The research,
published in the August 17, 2006, issue of "The New England Journal of
Medicine", shows, for example, that people ages 55 to 64 who are living
below the poverty line are six times more likely than the wealthiest group
to say they have functional limitations.
The study was conducted by the National Institute on Aging (NIA), part of
the National Institutes of Health, in collaboration with the University of
California, Berkeley, and the University of Toronto.
The researchers report that those living below the poverty line are the most
likely to say they have functional limitations, and, up to age 84, the odds
of having such limitations drops with each incremental increase in income.
They also note that older people are less likely to report functional
limitations with each increase in educational level, a measure that is
closely tied to income.
"We found that a 'gradient of disability' exists across the full
socioeconomic spectrum, as functional limitations proved inversely related
to household income," says senior author Jack M. Guralnik, M.D., Ph.D.,
chief of the NIA's Laboratory of Epidemiology, Demography and Biometry.
Improved understanding of the relationship between socioeconomic status and
disability is critical as the U.S. population ages, Guralnik notes. The rate
of disability decreased 1 to 2 percent annually during the 1980s and 1990s,
when trends were last reported, and the rate of decline was smaller among
those in the poorest socioeconomic groups.
Guralnik and co-authors Meredith Minkler, D.P.H., University of California,
Berkeley, and Esme Fuller-Thomson, Ph.D., University of Toronto, analyzed
data for more than 335,000 community-dwelling people 55 and older who
participated in the Census 2000 Supplementary Survey. Nearly one in four
respondents reported having a functional limitation, defined as a
long-lasting condition that substantially limits one or more basic physical
activities, such as walking, climbing stairs, reaching, lifting or carrying.
Functional limitation differences by income level were evident among those
55 to 64 years, 65 to 74 years, and 75 to 84 years, but differed more
dramatically in the younger age groups. Among all respondents under age 85,
even those whose incomes were at six times the poverty threshold had
significantly higher odds of reporting functional limitations, compared with
the wealthiest group.
The poverty threshold in 2000, the year the data were collected, was $8,259
for a person age 65 or older who lived alone and $17,761 for a four-person
household. The highest income category used in the analysis -- 700 percent
or more of the poverty line -- began at $57,813 for an older adult living
alone and $124,327 for a four-person household.