The Journals of Gerontology Series A: Biological Sciences and Medical Sciences Advance Access published online on October 7, 2009
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, doi:10.1093/gerona/glp148
Higher C-Reactive Protein and Soluble Tumor Necrosis Factor Receptor Levels Are Associated With Poor Physical Function and Disability: A Cross-Sectional Analysis of a Cohort of Late Middle-Aged African Americans
1 Division of Geriatrics, Department of Internal Medicine, Saint Louis University School of Medicine, Missouri
2 Geriatric Research Education Clinical Centre, VA Medical Center, St Louis, Missouri
3 Spencer Gulf Rural Health School, University of South Australia and the University of Adelaide, Whyalla
4 Centre for Rural Health and Community Development, University of South Australia, Whyalla
5 Department of Neurology and Psychiatry, Saint Louis University School of Medicine, Missouri
6 Regenstrief Institute, Inc., and Indiana University Center for Aging Research, Indiana University School of Medicine, Indianapolis
7 Department of Physical Therapy, Saint Louis University, Missouri
Address correspondence to Matthew T. Haren, PhD, SANSOM Institute, UniSA City East Campus (P5-06F), North Terrace, Adelaide, SA 5000, Australia. Email: matt.haren{at}unisa.edu.au
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Abstract |
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Background: This cohort of "late middle-aged" African Americans has an excess of disability. We aimed to determine associations of circulating cytokine receptors (sTNFR1, sTNFR2, and sIL-6R) and C-reactive protein (CRP) with disability, physical function, and body composition.
Methods: Stratified sampling of two socioeconomically diverse strata of St Louis, Missouri, occurred in 2000–2001. Inclusion criteria were self-reported black or African American race, born 1936–1950 inclusive, and Mini-Mental State Examination score of 16 or greater. In-home evaluations of handgrip strength, lean body mass percentage (LBM%), physical performance, upper and lower body functional limitations (UBFLs and LBFLs), and basic and instrumental activities of daily living (BADLs and IADLs) were collected. Of the 998 participants, 368 had blood sampled at baseline. Serum was stored and assayed in 2006.
Results: Absolute risks were LBFLs of 2 or more, 46%; UBFLs of 1 or more, 23.5%; BADLs of 2 or more, 20.6%; and IADLs of 2 or more, 22.5%. Independent of age, sex, and underlying comorbid conditions, higher CRP and sTNFR were associated with poorer physical performance (β = –1.462, p < .001 and β = –0.618, p = .003), UBFLs (odds ratio [OR] 2.26, 95% confidence interval [CI] 1.1–4.64 and OR 1.39, 95% CI 0.96–2.02), LBFLs (OR 2.30, 95% CI 1.19–4.45 and OR 1.91, 95% CI 1.26–2.91), BADLs (OR 2.79, 95% CI 1.03–5.96 and OR 1.66, 95% CI 1.11–2.46), and IADLs (OR 2.13, 95% CI 1.03–4.41 and OR 1.43, 95% CI 0.99–2.08). Higher CRP (β = –3.251, p <.001), sIL-6R (β = –6.152, p = .013), and lower adiponectin (β = 2.947, p = .052) were associated with lower LBM%.
Conclusions: Higher CRP and sTNFR are independently associated with disability and physical dysfunction. Higher sIL-6R, CRP, and lower adiponectin associate with lower LBM%.
Keywords Cytokine receptors; Aging; Disability
Received: May 17, 2008; Accepted: September 2, 2009