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Abstract

Objective

To test the hypothesis that oxidative stress is increased in patients with rheumatoid arthritis (RA) due to increased inflammation and contributes to the pathogenesis of atherosclerosis.

Methods

The independent association between urinary F2-isoprostane excretion, a measure of oxidative stress, and RA was tested using multiple linear regression models in 169 patients with RA and 92 control subjects, frequency matched for age, race, and sex. The relationship between F2-isoprostane excretion and coronary calcium, a marker of atherosclerosis, was examined in multivariable proportional odds logistic regression models that also assessed the interactions between oxidative stress and low-density lipoprotein and high-density lipoprotein (HDL) cholesterol.

Results

F2-isoprostane excretion was significantly higher in patients with RA (median 2.75 [interquartile range (IQR) 1.60–4.06] ng/mg creatinine) than in control subjects (median 1.86 [IQR 1.25–2.62] ng/mg creatinine; adjusted P = 0.006). In patients with RA, F2-isoprostanes were positively correlated with body mass index (P < 0.001), but not with disease activity or mediators of inflammation such as the Disease Activity Score in 28 joints or serum tumor necrosis factor α, interleukin-6, and C-reactive protein concentrations in adjusted multivariable models (P > 0.05 for all). In patients with RA, F2-isoprostanes significantly modified the effect of HDL cholesterol on coronary calcification (P = 0.02 for interaction) after adjustment for age, sex, and race. As F2-isoprostane levels increased, HDL lost its protective effect against coronary calcification.

Conclusion

Oxidative stress measured as F2-isoprostane excretion was higher in patients with RA than in control subjects. Among patients with RA, higher F2-isoprostane excretion and HDL cholesterol concentrations interacted significantly and were positively associated with the severity of coronary calcification.