Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Free Fatty Acids Are Associated with Insulin Resistance but Not Coronary Artery Atherosclerosis in Rheumatoid Arthritis.

Ormseth2,  Michelle J., Swift4,  Larry, Fazio4,  Sergio, Linton4,  MacRae F., Chung3,  Cecilia P., Raggi1,  Paolo, Rho2,  Young-Hee

Emory University
Vanderbilt University, Nashville, TN
Vanderbilt University, Baltimore, MD
Vanderbilt University
VUMC 23rd Ave South Pierce, Nashville, TN

Background:

Free fatty acids (FFA) affect insulin signaling and are implicated in the pathogenesis of insulin resistance and atherosclerosis. Inflammatory cytokines such as interleukin-6 (IL-6) increase lipolysis and thus FFA concentrations. Patients with rheumatoid arthritis (RA) have increased atherosclerosis that is associated with insulin resistance and higher IL-6 concentrations. Thus, a unifying mechanism underlying accelerated atherosclerosis in RA may be that increased IL-6 concentrations are associated with increased FFA concentrations resulting in insulin resistance and atherosclerosis.

Methods:

Clinical variables, concentrations of non-esterified FFA and inflammatory cytokines, homeostasis model assessment for insulin resistance (HOMA), and coronary artery calcium (CAC) were measured in 166 patients with RA and 92 controls. We compared FFA concentrations in RA and controls using Wilcoxon rank sum tests and a multivariable linear regression that adjusted for age, race, sex and BMI. Among RA patients, we assessed the relationship between FFA and inflammatory cytokines, HOMA, and CAC scores using Spearman correlation and multivariable regression analysis.

Results:

Patients with RA and controls were of similar age, race, sex and BMI. HOMA was significantly higher in RA (median [IQR]: 2.34 units [1.16–4.27]) than controls (0.83 units [0.54–1.79], p<0.001), as was CAC score (2.7 units [0.0–150.4] and 0.0 units [0.0–18.7], p=0.016). Triglyceride concentrations were similar (p=0.18), but LDL cholesterol was lower in RA than controls (111.0 mg/dL [88.0–135.0] and 122.0 mg/dL [104.0–145.0]) (p=0.016). FFA concentrations did not differ significantly in RA and controls (0.56 mmol/L [0.38–0.75] and 0.56 mmol/L [0.45–0.70], p=0.75). In RA, FFA concentration was positively correlated with CRP (rho=0.25, p=0.001), BMI (rho=0.16, p=0.046), HOMA (rho=0.20, p=0.011), triglycerides (rho=0.15, p=0.048), insulin (rho=0.18, p=0.024) and Framingham risk score (FRS) (rho=0.22, p=0.005); FFA were not correlated with IL-6 (p=0.48), TNF-a (p=0.29) or CAC score (p=0.62). After adjustment for age, race, sex and BMI, FFA remained associated with HOMA (p=0.011), insulin (p=0.023), CRP (p=0.009), triglycerides (p=0.004) and FRS (p=0.048).

Conclusions:

FFA concentrations do not differ significantly in patients with RA and controls. In patients with RA, FFA concentrations are correlated with obesity, insulin resistance, CRP concentrations and FRS, but not with IL-6, TNF-a and CAC score. FFA may contribute to insulin resistance, but do not provide a mechanistic link between inflammation, insulin resistance and coronary atherosclerosis in RA.

To cite this abstract, please use the following information:
Ormseth, Michelle J., Swift, Larry, Fazio, Sergio, Linton, MacRae F., Chung, Cecilia P., Raggi, Paolo, et al; Free Fatty Acids Are Associated with Insulin Resistance but Not Coronary Artery Atherosclerosis in Rheumatoid Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1034
DOI: 10.1002/art.28801

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