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Inflammatory Markers and Physical Function Among Older Adults with Knee Osteoarthritis
BRENDA W.J.H. PENNINX, HAIDER ABBAS, WALTER AMBROSIUS, BARBARA J. NICKLAS, CRALEN DAVIS, STEPHEN P. MESSIER, and MARCO PAHOR
ABSTRACT.
Methods. Data are from baseline assessments in 274 patients with knee OA participating in an exercise and nutrition intervention study. The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) was used to assess self-reported physical function, pain, and stiffness. The presence of disability was assessed, walking speed was calculated on the basis of the 6-minute walk test, and knee radiographs determined the radiographic severity of OA. Serum concentration of interleukin 6 (IL-6), C-reactive protein (CRP), tumor necrosis factor-a (TNF-a), and the soluble receptors IL-6sR, IL-2sR, TNF-sR1 and TNF-sR2 were measured by ELISA. Results. In multivariate regression analyses adjusted for age, sex, race, body mass index, comorbid conditions, and use of nonsteroid antiinflammatory drugs, higher serum levels of TNF-sR1 and TNF-sR2 were significantly associated with lower scores on the WOMAC physical function, with more symptoms of pain and stiffness, and with more reported physical disability. In addition, higher serum levels of TNF-sR1 and TNF-sR2 were significantly associated with slower walking speed, and tended to be associated with worse radiographic scores. Higher serum levels of IL-6 tended to be associated with slower walking speed, but no significant associations were observed for CRP, IL-6sR, or IL-2sR. Conclusion. Especially high levels of the soluble receptors of TNF-a were found to be associated with lower physical function, increased OA symptoms, and worse knee radiographic scores in older obese adults with knee OA. (J Rheumatol 2004;31:2027-31) Key Indexing Terms:
INFLAMMATION
From the Sticht Center on Aging, Section of Gerontology and Geriatric Medicine, Department of Internal Medicine; the Department of Public Health Sciences, Wake Forest University School of Medicine; and the Department of Health and Exercise Sciences, Wake Forest University, Winston-Salem, North Carolina, USA. Supported by the Wake Forest University Claude D. Pepper Older Americans Independence Center (P60-AG10484 and P30-AG21332) and the WFUSM General Clinical Research Center (M01-RR07122). B.W.J.H. Penninx, PhD; H. Abbas, MD; B.J. Nicklas, PhD; M. Pahor, MD, Sticht Center on Aging; W. Ambrosius, PhD; C. Davis, MS, Department of Public Health Sciences, Wake Forest University School of Medicine; S.P. Messier, PhD, Department of Health and Exercise Sciences, Wake Forest University. Address reprint requests to Dr. B. Nicklas, Sticht Center on Aging, Wake Forest University School of Medicine, 1 Medical Center Boulevard, Winston-Salem, NC 27157. E-mail: bnicklas@wfubmc.edu Submitted December 5, 2003; revision accepted April 19, 2004. |