The association of plasma IL-6 levels with functional disability in community-dwelling elderly.
BACKGROUND
IL-6 is a multifunctional cytokine that has been shown to increase with age.


METHODS
Plasma IL-6 was measured by ELISA in 1,727 community-dwelling elderly subjects whose blood was drawn during the third in-person survey of the Duke Established Populations for Epidemiologic Studies of the Elderly (EPESE). Demographics, functional status (disability), and disease states were determined. Correlations of these factors with IL-6 were analyzed with Spearman's Rho while differences between groups were assessed by Wilcoxon test.


RESULTS
IL-6 levels were higher with age (p = .0001) even in this older population (> 70 years). There was a positive correlation between IL-6 and functional disability for each of the functional status measures (p = .0001), as well as a correlation between self-rated health and IL-6. Significantly higher median levels of IL-6 were found in subjects reporting prevalent cancer, heart attack, and high blood pressure, but not diabetes or arthritis. The association between age and functional status with high IL-6 remained when all other variables were controlled, in multivariable analysis.


CONCLUSIONS
This association between increased plasma IL-6 levels and functional status suggests that dysregulation of IL-6 may be related to the functional disability seen with aging, and that IL-6 may be useful as a component of an overall marker of health.
Cohen
H J
HJ
Center for the Study of Aging and Human Development, Claude D. Pepper Older Americans Independence Center, Duke University Medical Center, Durham, North Carolina, USA.
Pieper
C F
CF
Harris
T
T
Rao
K M
KM
Currie
M S
MS
D000368:Aged; D000375:Aging / Q000097:blood; D003154:Community Medicine / Q000379:methods*; D006233:Persons with Disabilities; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006304:Health Status; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D015999:Multivariate Analysis; D012647:Self-Assessment
D015850:Interleukin-6