Single regression analysis between IL-6 and markers of chronic inflammation and oxidative stress. IL-6 was significantly correlated to (A) IL-1β (P = .020), (B) C-reactive protein (P < .001), (C) reactive oxygen species (ROS; P < .001), and (D) fibrinogen (Fbg; P = .001). The central straight line corresponds to the best-fit linear regression line. The two curved lines surrounding the best-fit line define the 95% confidence interval of the regression line. The graphs also show the prediction interval (the curves defining the prediction interval are further from the regression line than the confidence lines).