Clinical significance of the augmentation index in patients with preserved kidney function

The augmentation index (AIx) indicates arterial wave reflection. Clinical studies have shown a relationship between an elevated AIx and cardiovascular disease. This cross-sectional study attempted to clarify the clinical significance of AIx in patients with preserved kidney function.

The subjects were 321 patients with preserved kidney function (an estimated glomerular filtration rate ≥60 mL/min/1.73 m2 and normoalbuminuria) but with no history of cardiovascular events. The AIx was determined in the radial artery by means of tonometry, and the relationships of the AIx to kidney function and markers of atherosclerosis were examined.

A significant positive correlation (r=0.30; p<0.001) was found between the AIx and the urinary albumin concentration. The AIx showed a significant positive correlation (r=0.28; p<0.001) with the serum high-sensitivity C-reactive protein concentration, as a marker of inflammation; with the urinary 8-iso-prostaglandin F2α concentration (r=0.31; p<0.001), as a marker of oxidative stress; and with the cardio-ankle vascular index (r=0.17; p<0.01), as a marker of systemic arterial stiffness. Multiple regression analysis indicated that the urinary 8-iso-prostaglandin F2α concentration (t=5.1; p<0.001), serum high-sensitivity C-reactive protein concentration (t=4.9; p<0.001), and urinary albumin concentration (t=3.6; p<0.01) were independent variables for AIx after adjustment.

These findings indicate that the AIx reflects inflammation, oxidative stress, and the urinary albumin concentration in patients with preserved kidney function.