Risk of disability increasing in older obese population in the U.S.

Nov 6 2007

The older obese population in the U.S. appear to be experiencing more impairments in functional abilities related to movement, although there have been improvements in the cardiovascular health of this population, according to a study in the November 7 issue of JAMA.

Recent studies have suggested that the obese population may have grown healthier since the 1960s, with the prevalence of high cholesterol and high blood pressure declining among obese individuals. It is unclear, however, whether improvements in cardiovascular risk factors have been accompanied by improvements in other health outcomes, according to background information in the article.

Dawn Alley, Ph.D., and Virginia W. Chang, M.D., Ph.D., of the University of Pennsylvania, Philadelphia, conducted a study to determine whether the association between obesity and disability has changed among individuals age 60 years and older. A previous analysis of trends in obesity and disability showed a constant effect of obesity on disability over time, with disability increasing in both obese and nonobese populations. “Disability in this age group is of particular importance, given the current context of population aging and an increasing prevalence of obesity among older-aged individuals. Furthermore, obesity-associated disability is associated with significant burden in terms of both quality of life and health care costs in this age group,” the authors write.

The researchers analyzed data from the nationally representative National Health and Nutrition Examination Surveys (NHANES III [1988-1994] and NHANES 1999-2004). The population set for this study included 9,928 adults age 60 years and older with measured body mass index (BMI). The participants were surveyed regarding difficulty or inability to perform tasks in two disability domains: functional limitations (walking one-fourth mile, walking up 10 steps, stooping, lifting 10 pounds, walking between rooms, and standing from an armless chair) and activities of daily living (ADL) limitations (getting in and out of bed, eating, and dressing).

The researchers found that the prevalence of obesity (a BMI of 30 or greater) increased by 8.2 percentage points over time from 23.5 percent of the population age 60 years and older in 1988-1994 (time 1) to 31.7 percent in 1999-2004 (time 2). During both time ranges, obese individuals were more likely than normal-weight individuals to have a functional impairment. During time 2, obese individuals were also more likely to have an ADL impairment. Examining trends over time showed that the prevalence of functional impairment did not change significantly among normal-weight individuals, but increased among obese individuals by 5.4 percent, from 36.8 percent to 42.2 percent.

The odds of being functionally impaired did not change for nonobese individuals from time 1 to time 2, but increased 43 percent among obese individuals. There was an increasing association between obesity and disability over time. At time 1, obese individuals had a 78 percent increased odds of functional impairment relative to those with normal weight. At time 2, the odds of functional limitation for obese individuals were 2.75 times greater than for those with normal weight.

In terms of ADL limitations, the risk of ADL impairment in obese older individuals was not significantly different from normal weight during time 1. Between 1988-1994 and 1999-2004, the odds of ADL impairment decreased by 34 percent within the nonobese population, but did not change in the obese population. At time 2, the odds of ADL impairment for obese individuals was about twice as great than for those with normal weight.

“Obese participants in NHANES 1999-2004 were more likely to report functional impairments than obese participants in NHANES III (1988-1994), which suggests an increasing risk of disability in the obese population. Furthermore, reductions in ADL disability observed among nonobese older individuals did not occur among obese individuals. Taken together, these findings suggest that recent improvements in cardiovascular health have not been accompanied by a reduction in disability burden among obese individuals; instead, the risk of some types of disability is actually increasing,” the authors conclude.

http://jama.ama-assn.org/