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Fetuin-A and Change in Body Composition in Older Persons

Division of Nephrology (J.H.I.), Department of Medicine, and Division of Preventive Medicine (J.H.I., C.L.W.), Department of Family and Preventive Medicine, University of California San Diego, and Nephrology Section (J.H.I.), Veterans Affairs San Diego Healthcare System, San Diego, California 92161; Division of Nephrology (G.M.C.), Department of Medicine, Stanford University, Palo Alto, California 94305; Intramural Research Program (A.K., T.B.H.), Laboratory for Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, Maryland 20892; Department of Preventive Medicine (K.C.J., F.A.T.), University of Tennessee Health Sciences Center, Memphis, Tennessee 38163; Department of Epidemiology (J.A.C.), University of Pittsburgh, Pittsburgh, Pennsylvania 15260; Department of Medicine (S.R.C.), California Pacific Medical Center, San Francisco, California 94120; San Francisco Coordinating Center (S.R.C.), San Francisco, California 94107; Departments of Medicine (S.R.C., M.G.S.) and Epidemiology and Biostatistics (M.G.S.), University of California, San Francisco, San Francisco, California California 94143; and General Internal Medicine Section (M.G.S.), San Francisco Veterans Affairs Medical Center, San Francisco, California 94121

Address all correspondence and requests for reprints to: Joachim H. Ix, M.D., M.A.S., Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, and San Diego Veterans Affairs Healthcare System, 3350 La Jolla Village Drive, Mail Code 111-H, San Diego, California 92161. E-mail: joeix{at}ucsd.edu.

Context: Fetuin-A inhibits the insulin receptor in vitro. Higher serum fetuin-A concentrations are associated with type 2 diabetes longitudinally and greater adiposity in cross-sectional analyses. Whether higher fetuin-A concentrations are associated with accumulation of adiposity over time is unknown.

Objective: To determine the association of fetuin-A levels with changes in body composition over 5 yr.

Study Design: Observational cohort study nested in the Health Aging and Body Composition Study.

Predictor: Serum fetuin-A levels.

Outcomes: Visceral adipose tissue (VAT), abdominal sc adipose tissue, and thigh muscle area by computed tomography, and waist circumference and body mass index were measured at baseline and again after 5 yr. Percent change and extreme change (>1.5 SDs) in each measure were calculated.

Results: Over 5 yr, subjects lost body mass in each measure, including 6% decline in VAT. Yet each SD (0.42 g/liter) higher fetuin-A concentration was associated with a 5.5% increase in VAT over 5 yr (95% confidence interval 1.9–9.2%; P = 0.003) in models adjusted for age, sex, race, clinical site, diabetes, physical activity, triglycerides, kidney function, and the baseline VAT score. Similarly, higher fetuin-A concentrations were associated with extreme VAT gain (relative risk 1.70, 95% confidence interval 1.12–2.60, P = 0.01). Fetuin-A concentrations were not statistically significant associated with change in any other measures of body composition (P > 0.20).

Conclusions: Higher fetuin-A concentrations are associated with the accumulation of VAT in well-functioning, community-living older persons. The mechanisms linking fetuin-A, VAT, and insulin resistance remain to be determined.