Study results being presented at international endocrinology meeting in San Francisco
Older women with abnormal levels of two substances -- a growth hormone and a biological marker tied to inflammation -- may be at higher risk for becoming disabled or dying, according to the results of a new study. The study, led by a University of Maryland School of Medicine researcher, will be presented June 22 at an international endocrinology conference in San Francisco.
Using data from a three-year study of 718 women over age 65 with physical disabilities, researchers found that those who had low levels of a hormone called insulin-like growth factor-1 (IGF-1) and high levels of interleukin-6 (IL-6) were more likely to have serious problems walking and caring for themselves than women with normal test results.
"These women were also twice as likely to die within five years compared to those with normal levels of IGF-1 and IL-6," says the lead investigator, Anne R. Cappola, M.D., Sc.M., an endocrinologist at the University of Maryland Medical Center and an assistant professor of medicine at the University of Maryland School of Medicine.
"We do not know whether the abnormal levels contribute to the decline in health of elderly women or are just markers," she says. "If they are a cause, some kind of intervention or drug therapy might help those at risk. It could be that they just need to be monitored more closely."
But, she adds, if the abnormal levels are only markers, that would still help to identify patients at risk of developing problems.
"Because it is an observational study, we can't prove cause and effect. But if other studies confirm our findings, testing for IGF-1 and IL-6 could be clinically useful in the future to identify older people at risk for disabilities and death," says Dr. Cappola, who will present the results at ENDO 2002, the 84th annual meeting of The Endocrine Society, in San Francisco, Calif.
Dr. Cappola and researchers from the National Institute on Aging and the Johns Hopkins Medical Institutions looked at levels of IGF-1 and IL-6 in 718 moderately to severely disabled women, who took part in the Women's Health and Aging Study I. The study, funded by the National Institute on Aging, was conducted from 1992 to 1995 in Baltimore.
"We discovered that older women with both low IGF-1 levels and high IL-6 levels were five times more likely to have difficulty walking a quarter of a mile or climbing stairs compared to women who had normal test levels," says Dr. Cappola.
She says that these at-risk women were 10 times more likely to have severe limitations in their ability to walk. They had a 27 percent increased risk of having difficulty or being unable to perform daily tasks, such as bathing, dressing, eating and using the toilet, and a 68 percent increased risk of having problems with other chores, such as light housework, shopping and preparing meals.
According to Dr. Cappola, previous studies have detected abnormal levels of IL-6 or IGF-1 in older people who become disabled, but this is the first study to look at both factors together.
Levels of IGF-1 and IL-6 change as people age, but the degree to which this occurs appears to signal problems. The growth hormone IGF-1, which is produced in the liver, affects bone mass and strength. Interleukin-6 is associated with an inflammatory response by the body. Neither is routinely measured clinically.
In analyzing the data, researchers tried to factor out all other possibilities for the women's disabilities, taking into account not only their age, race, education and body mass, but also whether they smoked or had chronic medical conditions, such as diabetes or heart disease.
The average age of the women was 77.6 years, and 28.9 percent of them were African-American. Twelve percent smoked, 10.2 percent had congestive heart failure and 15.7 percent had diabetes. Seventy-two percent of them had difficulty caring for themselves on a daily basis, while 47 percent had problems walking or climbing stairs.
"The bottom line is that it seems that the women were worse off if they had both a low level of IGF-1 and a high level of IL-6 than if they had neither, but we're not sure what causes that," Dr. Cappola says. "Our work represents an initial step toward understanding what is really going on physiologically with older women who are disabled and for developing a risk profile for frailty in older women."
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