Pathologic Background of Abnormal Serum Amyloid A and Interleukin-6 Levels Revealed by a Piecewise Linear Regression Model in the Population of Diabetic Patients

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Background The relationship between serum amyloid A (SAA) as an inflammation marker and interleukin-6 (IL-6) as a factor inducing SAA provides an important insight into vascular lesions in a population of diabetic patients.
Methods We investigated the use of piecewise linear regression as a replacement for the simple correlation diagram method in order to uncover the pathologic condition hidden behind their correlation.
Results and Conclusions Significant associations were found between SAA and IL-6 (r=0.469) and between ferritin (Ft) and lipoprotein lipase (LPL) mass (r=0.314). We attempted to detect pathologic tendencies related to SAA in the abnormal range using the piecewise linear regression method, and confirmed the close relationship between SAA and IL-6 related to the mechanism for cytokine induction. In addition, our analyses characterized how the inflammation marker SAA was related to LPL mass as a marker of endothelial cell damage and Ft as an oxidative stress marker protein with antioxidant properties.